Fix the skill
This commit is contained in:
Yaojia Wang
@@ -1,314 +1,274 @@
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# Backend Development Patterns
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# .NET Development Best Practices
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Backend architecture patterns for Python/FastAPI/PostgreSQL applications.
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## API Design
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### RESTful Structure
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## Project Structure
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```
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GET /api/v1/documents # List
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GET /api/v1/documents/{id} # Get
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POST /api/v1/documents # Create
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PUT /api/v1/documents/{id} # Replace
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PATCH /api/v1/documents/{id} # Update
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DELETE /api/v1/documents/{id} # Delete
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GET /api/v1/documents?status=processed&sort=created_at&limit=20&offset=0
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src/
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Domain/ # Entities, value objects, domain events
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Application/ # Use cases, DTOs, interfaces
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Infrastructure/ # EF Core, external services
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Api/ # Controllers, middleware, filters
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tests/
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Unit/
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Integration/
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```
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### FastAPI Route Pattern
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## Code Style
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```python
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from fastapi import APIRouter, HTTPException, Depends, Query, File, UploadFile
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from pydantic import BaseModel
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```csharp
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// Use records for DTOs and value objects
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public sealed record CreateDocumentRequest(string Name, string Type);
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router = APIRouter(prefix="/api/v1", tags=["inference"])
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// Use primary constructors
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public class DocumentService(IRepository<Document> repo, ILogger<DocumentService> logger)
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{
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public async Task<Document?> GetAsync(Guid id, CancellationToken ct) =>
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await repo.GetByIdAsync(id, ct);
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}
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@router.post("/infer", response_model=ApiResponse[InferenceResult])
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async def infer_document(
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file: UploadFile = File(...),
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confidence_threshold: float = Query(0.5, ge=0, le=1),
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service: InferenceService = Depends(get_inference_service)
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) -> ApiResponse[InferenceResult]:
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result = await service.process(file, confidence_threshold)
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return ApiResponse(success=True, data=result)
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// Prefer expression body for simple methods
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public Document? FindById(Guid id) => _documents.FirstOrDefault(d => d.Id == id);
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// Use collection expressions
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int[] numbers = [1, 2, 3];
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List<string> names = ["Alice", "Bob"];
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```
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### Consistent Response Schema
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## Async/Await
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```python
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from typing import Generic, TypeVar
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T = TypeVar('T')
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```csharp
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// Always pass CancellationToken
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public async Task<Document> GetAsync(Guid id, CancellationToken ct)
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class ApiResponse(BaseModel, Generic[T]):
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success: bool
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data: T | None = None
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error: str | None = None
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meta: dict | None = None
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// Use ConfigureAwait(false) in libraries
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await _httpClient.GetAsync(url, ct).ConfigureAwait(false);
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// Avoid async void (except event handlers)
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public async Task ProcessAsync() { } // Good
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public async void Process() { } // Bad
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// Use ValueTask for hot paths with frequent sync completion
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public ValueTask<int> GetCachedCountAsync()
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```
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## Core Patterns
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## Dependency Injection
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### Repository Pattern
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```csharp
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// Register by interface
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builder.Services.AddScoped<IDocumentService, DocumentService>();
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```python
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from typing import Protocol
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// Use Options pattern for configuration
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builder.Services.Configure<AppSettings>(builder.Configuration.GetSection("App"));
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class DocumentRepository(Protocol):
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def find_all(self, filters: dict | None = None) -> list[Document]: ...
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def find_by_id(self, id: str) -> Document | None: ...
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def create(self, data: dict) -> Document: ...
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def update(self, id: str, data: dict) -> Document: ...
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def delete(self, id: str) -> None: ...
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public class MyService(IOptions<AppSettings> options)
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{
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private readonly AppSettings _settings = options.Value;
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}
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// Avoid service locator pattern
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// Bad: var service = serviceProvider.GetService<IMyService>();
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// Good: Constructor injection
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```
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### Service Layer
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## Entity Framework Core
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```python
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class InferenceService:
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def __init__(self, model_path: str, use_gpu: bool = True):
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self.pipeline = InferencePipeline(model_path=model_path, use_gpu=use_gpu)
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```csharp
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// Always use AsNoTracking for read-only queries
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await _context.Documents.AsNoTracking().ToListAsync(ct);
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async def process(self, file: UploadFile, confidence_threshold: float) -> InferenceResult:
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temp_path = self._save_temp_file(file)
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try:
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return self.pipeline.process_pdf(temp_path)
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finally:
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temp_path.unlink(missing_ok=True)
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```
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// Use projection to select only needed fields
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await _context.Documents
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.Where(d => d.Status == "Active")
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.Select(d => new DocumentDto(d.Id, d.Name))
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.ToListAsync(ct);
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### Dependency Injection
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// Prevent N+1 with Include or projection
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await _context.Documents.Include(d => d.Labels).ToListAsync(ct);
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```python
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from functools import lru_cache
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from pydantic_settings import BaseSettings
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// Use explicit transactions for multiple operations
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await using var tx = await _context.Database.BeginTransactionAsync(ct);
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class Settings(BaseSettings):
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db_host: str = "localhost"
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db_password: str
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model_path: str = "runs/train/invoice_fields/weights/best.pt"
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class Config:
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env_file = ".env"
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@lru_cache()
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def get_settings() -> Settings:
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return Settings()
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def get_inference_service(settings: Settings = Depends(get_settings)) -> InferenceService:
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return InferenceService(model_path=settings.model_path)
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```
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## Database Patterns
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### Connection Pooling
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```python
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from psycopg2 import pool
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from contextlib import contextmanager
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db_pool = pool.ThreadedConnectionPool(minconn=2, maxconn=10, **db_config)
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@contextmanager
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def get_db_connection():
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conn = db_pool.getconn()
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try:
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yield conn
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finally:
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db_pool.putconn(conn)
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```
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### Query Optimization
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```python
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# GOOD: Select only needed columns
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cur.execute("""
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SELECT id, status, fields->>'InvoiceNumber' as invoice_number
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FROM documents WHERE status = %s
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ORDER BY created_at DESC LIMIT %s
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""", ('processed', 10))
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# BAD: SELECT * FROM documents
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```
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### N+1 Prevention
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```python
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# BAD: N+1 queries
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for doc in documents:
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doc.labels = get_labels(doc.id) # N queries
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# GOOD: Batch fetch with JOIN
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cur.execute("""
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SELECT d.id, d.status, array_agg(l.label) as labels
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FROM documents d
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LEFT JOIN document_labels l ON d.id = l.document_id
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GROUP BY d.id, d.status
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""")
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```
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### Transaction Pattern
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```python
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def create_document_with_labels(doc_data: dict, labels: list[dict]) -> str:
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with get_db_connection() as conn:
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try:
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with conn.cursor() as cur:
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cur.execute("INSERT INTO documents ... RETURNING id", ...)
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doc_id = cur.fetchone()[0]
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for label in labels:
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cur.execute("INSERT INTO document_labels ...", ...)
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conn.commit()
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return doc_id
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except Exception:
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conn.rollback()
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raise
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```
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## Caching
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```python
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from cachetools import TTLCache
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_cache = TTLCache(maxsize=1000, ttl=300)
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def get_document_cached(doc_id: str) -> Document | None:
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if doc_id in _cache:
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return _cache[doc_id]
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doc = repo.find_by_id(doc_id)
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if doc:
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_cache[doc_id] = doc
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return doc
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// Configure entities with IEntityTypeConfiguration
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public class DocumentConfiguration : IEntityTypeConfiguration<Document>
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{
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public void Configure(EntityTypeBuilder<Document> builder)
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{
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builder.HasKey(d => d.Id);
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builder.Property(d => d.Name).HasMaxLength(200).IsRequired();
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builder.HasIndex(d => d.Status);
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}
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}
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```
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## Error Handling
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### Exception Hierarchy
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```csharp
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// Create domain-specific exceptions
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public class NotFoundException(string resource, Guid id)
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: Exception($"{resource} not found: {id}");
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```python
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class AppError(Exception):
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def __init__(self, message: str, status_code: int = 500):
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self.message = message
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self.status_code = status_code
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// Use global exception handler
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public class GlobalExceptionHandler(ILogger<GlobalExceptionHandler> logger) : IExceptionHandler
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{
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public async ValueTask<bool> TryHandleAsync(HttpContext ctx, Exception ex, CancellationToken ct)
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{
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logger.LogError(ex, "Error: {Message}", ex.Message);
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ctx.Response.StatusCode = ex is NotFoundException ? 404 : 500;
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await ctx.Response.WriteAsJsonAsync(new { error = ex.Message }, ct);
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return true;
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}
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}
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class NotFoundError(AppError):
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def __init__(self, resource: str, id: str):
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super().__init__(f"{resource} not found: {id}", 404)
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class ValidationError(AppError):
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def __init__(self, message: str):
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super().__init__(message, 400)
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// Use Result pattern for expected failures
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public Result<Document> Validate(CreateRequest request) =>
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string.IsNullOrEmpty(request.Name)
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? Result<Document>.Fail("Name is required")
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: Result<Document>.Ok(new Document(request.Name));
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```
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### FastAPI Exception Handler
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## Validation
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```python
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@app.exception_handler(AppError)
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async def app_error_handler(request: Request, exc: AppError):
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return JSONResponse(status_code=exc.status_code, content={"success": False, "error": exc.message})
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```csharp
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// Use FluentValidation
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public class CreateDocumentValidator : AbstractValidator<CreateDocumentRequest>
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{
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public CreateDocumentValidator()
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{
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RuleFor(x => x.Name).NotEmpty().MaximumLength(200);
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RuleFor(x => x.Type).Must(BeValidType).WithMessage("Invalid document type");
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}
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}
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@app.exception_handler(Exception)
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async def generic_error_handler(request: Request, exc: Exception):
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logger.error(f"Unexpected error: {exc}", exc_info=True)
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return JSONResponse(status_code=500, content={"success": False, "error": "Internal server error"})
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// Or use Data Annotations for simple cases
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public record CreateRequest(
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[Required, MaxLength(200)] string Name,
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[Range(1, 100)] int Quantity);
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```
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### Retry with Backoff
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## Logging
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```python
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async def retry_with_backoff(fn, max_retries: int = 3, base_delay: float = 1.0):
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last_error = None
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for attempt in range(max_retries):
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try:
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return await fn() if asyncio.iscoroutinefunction(fn) else fn()
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except Exception as e:
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last_error = e
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if attempt < max_retries - 1:
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await asyncio.sleep(base_delay * (2 ** attempt))
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raise last_error
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```csharp
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// Use structured logging with templates
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logger.LogInformation("Processing document {DocumentId} for user {UserId}", docId, userId);
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// Use appropriate log levels
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logger.LogDebug("Cache hit for key {Key}", key); // Development details
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logger.LogInformation("Document {Id} created", id); // Normal operations
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logger.LogWarning("Retry attempt {Attempt} for {Op}", n, op); // Potential issues
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logger.LogError(ex, "Failed to process {DocumentId}", id); // Errors
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// Configure log filtering in appsettings
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{
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"Logging": {
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"LogLevel": {
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"Default": "Information",
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"Microsoft.AspNetCore": "Warning",
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"Microsoft.EntityFrameworkCore": "Warning"
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}
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}
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}
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```
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## Rate Limiting
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## API Design
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```python
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from time import time
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from collections import defaultdict
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```csharp
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[ApiController]
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[Route("api/v1/[controller]")]
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public class DocumentsController(IDocumentService service) : ControllerBase
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{
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[HttpGet("{id:guid}")]
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[ProducesResponseType<Document>(200)]
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[ProducesResponseType(404)]
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public async Task<IActionResult> Get(Guid id, CancellationToken ct)
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{
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var doc = await service.GetAsync(id, ct);
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return doc is null ? NotFound() : Ok(doc);
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}
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class RateLimiter:
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def __init__(self):
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self.requests: dict[str, list[float]] = defaultdict(list)
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def check_limit(self, identifier: str, max_requests: int, window_sec: int) -> bool:
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now = time()
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self.requests[identifier] = [t for t in self.requests[identifier] if now - t < window_sec]
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if len(self.requests[identifier]) >= max_requests:
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return False
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self.requests[identifier].append(now)
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return True
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limiter = RateLimiter()
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@app.middleware("http")
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async def rate_limit_middleware(request: Request, call_next):
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ip = request.client.host
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if not limiter.check_limit(ip, max_requests=100, window_sec=60):
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return JSONResponse(status_code=429, content={"error": "Rate limit exceeded"})
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return await call_next(request)
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[HttpPost]
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public async Task<IActionResult> Create(CreateRequest request, CancellationToken ct)
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{
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var doc = await service.CreateAsync(request, ct);
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return CreatedAtAction(nameof(Get), new { id = doc.Id }, doc);
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}
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}
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```
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## Logging & Middleware
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## Testing
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### Request Logging
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```csharp
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// Use descriptive test names
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[Fact]
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public async Task GetById_WithValidId_ReturnsDocument()
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{
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// Arrange
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var repo = Substitute.For<IRepository<Document>>();
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repo.GetByIdAsync(Arg.Any<Guid>(), Arg.Any<CancellationToken>())
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.Returns(new Document("Test"));
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var service = new DocumentService(repo);
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```python
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@app.middleware("http")
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async def log_requests(request: Request, call_next):
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request_id = str(uuid.uuid4())[:8]
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start_time = time.time()
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logger.info(f"[{request_id}] {request.method} {request.url.path}")
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response = await call_next(request)
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duration_ms = (time.time() - start_time) * 1000
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logger.info(f"[{request_id}] Completed {response.status_code} in {duration_ms:.2f}ms")
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return response
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// Act
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var result = await service.GetAsync(Guid.NewGuid(), CancellationToken.None);
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// Assert
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result.Should().NotBeNull();
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result!.Name.Should().Be("Test");
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}
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// Use WebApplicationFactory for integration tests
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public class ApiTests(WebApplicationFactory<Program> factory) : IClassFixture<WebApplicationFactory<Program>>
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{
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[Fact]
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public async Task GetDocuments_ReturnsSuccess()
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{
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var client = factory.CreateClient();
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var response = await client.GetAsync("/api/v1/documents");
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response.StatusCode.Should().Be(HttpStatusCode.OK);
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}
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}
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```
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### Structured Logging
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## Performance
|
||||
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```python
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class JSONFormatter(logging.Formatter):
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def format(self, record):
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return json.dumps({
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"timestamp": datetime.utcnow().isoformat(),
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"level": record.levelname,
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"message": record.getMessage(),
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"module": record.module,
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})
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```csharp
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// Use IMemoryCache for frequently accessed data
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public class CachedService(IMemoryCache cache, IRepository<Document> repo)
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{
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public async Task<Document?> GetAsync(Guid id, CancellationToken ct) =>
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await cache.GetOrCreateAsync($"doc:{id}", async entry =>
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{
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entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(5);
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return await repo.GetByIdAsync(id, ct);
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});
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}
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// Use pagination for large collections
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public async Task<PagedResult<Document>> GetPagedAsync(int page, int size, CancellationToken ct) =>
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new(
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await _context.Documents.Skip((page - 1) * size).Take(size).ToListAsync(ct),
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||||
await _context.Documents.CountAsync(ct)
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);
|
||||
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||||
// Use IAsyncEnumerable for streaming large datasets
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public async IAsyncEnumerable<Document> StreamAllAsync([EnumeratorCancellation] CancellationToken ct)
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{
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await foreach (var doc in _context.Documents.AsAsyncEnumerable().WithCancellation(ct))
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yield return doc;
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}
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```
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## Background Tasks
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||||
## Security
|
||||
|
||||
```python
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from fastapi import BackgroundTasks
|
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```csharp
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||||
// Never hardcode secrets
|
||||
var apiKey = builder.Configuration["ApiKey"]; // From environment/secrets
|
||||
|
||||
def send_notification(document_id: str, status: str):
|
||||
logger.info(f"Notification: {document_id} -> {status}")
|
||||
// Use parameterized queries (EF Core does this automatically)
|
||||
// Bad: $"SELECT * FROM Users WHERE Id = {id}"
|
||||
// Good: _context.Users.Where(u => u.Id == id)
|
||||
|
||||
@router.post("/infer")
|
||||
async def infer(file: UploadFile, background_tasks: BackgroundTasks):
|
||||
result = await process_document(file)
|
||||
background_tasks.add_task(send_notification, result.document_id, "completed")
|
||||
return result
|
||||
// Validate and sanitize all inputs
|
||||
// Use HTTPS in production
|
||||
// Implement rate limiting
|
||||
builder.Services.AddRateLimiter(options => { ... });
|
||||
```
|
||||
|
||||
## Key Principles
|
||||
|
||||
- Repository pattern: Abstract data access
|
||||
- Service layer: Business logic separated from routes
|
||||
- Dependency injection via `Depends()`
|
||||
- Connection pooling for database
|
||||
- Parameterized queries only (no f-strings in SQL)
|
||||
- Batch fetch to prevent N+1
|
||||
- Consistent `ApiResponse[T]` format
|
||||
- Exception hierarchy with proper status codes
|
||||
- Rate limit by IP
|
||||
- Structured logging with request ID
|
||||
@@ -1,665 +1,234 @@
|
||||
---
|
||||
name: coding-standards
|
||||
description: Universal coding standards, best practices, and patterns for Python, FastAPI, and data processing development.
|
||||
description: .NET/C# coding standards and best practices.
|
||||
---
|
||||
|
||||
# Coding Standards & Best Practices
|
||||
# .NET Coding Standards
|
||||
|
||||
Python coding standards for the Invoice Master project.
|
||||
## Core Principles
|
||||
|
||||
## Code Quality Principles
|
||||
- **Readability First** - Clear names, self-documenting code
|
||||
- **KISS** - Simplest solution that works
|
||||
- **DRY** - Extract common logic, avoid copy-paste
|
||||
- **YAGNI** - Don't build features before needed
|
||||
|
||||
### 1. Readability First
|
||||
- Code is read more than written
|
||||
- Clear variable and function names
|
||||
- Self-documenting code preferred over comments
|
||||
- Consistent formatting (follow PEP 8)
|
||||
## Naming Conventions
|
||||
|
||||
### 2. KISS (Keep It Simple, Stupid)
|
||||
- Simplest solution that works
|
||||
- Avoid over-engineering
|
||||
- No premature optimization
|
||||
- Easy to understand > clever code
|
||||
```csharp
|
||||
// PascalCase: Types, methods, properties, public fields
|
||||
public class DocumentService { }
|
||||
public async Task<Document> GetByIdAsync(Guid id) { }
|
||||
public string InvoiceNumber { get; init; }
|
||||
|
||||
### 3. DRY (Don't Repeat Yourself)
|
||||
- Extract common logic into functions
|
||||
- Create reusable utilities
|
||||
- Share modules across the codebase
|
||||
- Avoid copy-paste programming
|
||||
// camelCase: Parameters, local variables, private fields with underscore
|
||||
private readonly ILogger<DocumentService> _logger;
|
||||
public void Process(string documentId, int pageCount) { }
|
||||
|
||||
### 4. YAGNI (You Aren't Gonna Need It)
|
||||
- Don't build features before they're needed
|
||||
- Avoid speculative generality
|
||||
- Add complexity only when required
|
||||
- Start simple, refactor when needed
|
||||
// Interfaces: I prefix
|
||||
public interface IDocumentRepository { }
|
||||
|
||||
## Python Standards
|
||||
|
||||
### Variable Naming
|
||||
|
||||
```python
|
||||
# GOOD: Descriptive names
|
||||
invoice_number = "INV-2024-001"
|
||||
is_valid_document = True
|
||||
total_confidence_score = 0.95
|
||||
|
||||
# BAD: Unclear names
|
||||
inv = "INV-2024-001"
|
||||
flag = True
|
||||
x = 0.95
|
||||
// Async methods: Async suffix
|
||||
public async Task<Document> LoadAsync(CancellationToken ct)
|
||||
```
|
||||
|
||||
### Function Naming
|
||||
## Modern C# Features
|
||||
|
||||
```python
|
||||
# GOOD: Verb-noun pattern with type hints
|
||||
def extract_invoice_fields(pdf_path: Path) -> dict[str, str]:
|
||||
"""Extract fields from invoice PDF."""
|
||||
...
|
||||
```csharp
|
||||
// Records for DTOs and value objects
|
||||
public sealed record CreateDocumentRequest(string Name, string Type);
|
||||
public sealed record DocumentDto(Guid Id, string Name, DateTime CreatedAt);
|
||||
|
||||
def calculate_confidence(predictions: list[float]) -> float:
|
||||
"""Calculate average confidence score."""
|
||||
...
|
||||
// Primary constructors
|
||||
public class DocumentService(IRepository<Document> repo, ILogger<DocumentService> logger)
|
||||
{
|
||||
public async Task<Document?> GetAsync(Guid id, CancellationToken ct) =>
|
||||
await repo.GetByIdAsync(id, ct);
|
||||
}
|
||||
|
||||
def is_valid_bankgiro(value: str) -> bool:
|
||||
"""Check if value is valid Bankgiro number."""
|
||||
...
|
||||
// Pattern matching
|
||||
var message = result switch
|
||||
{
|
||||
{ IsSuccess: true, Value: var doc } => $"Found: {doc.Name}",
|
||||
{ Error: var err } => $"Error: {err}",
|
||||
_ => "Unknown"
|
||||
};
|
||||
|
||||
# BAD: Unclear or noun-only
|
||||
def invoice(path):
|
||||
...
|
||||
// Collection expressions
|
||||
int[] numbers = [1, 2, 3];
|
||||
List<string> names = ["Alice", "Bob"];
|
||||
|
||||
def confidence(p):
|
||||
...
|
||||
|
||||
def bankgiro(v):
|
||||
...
|
||||
// Null coalescing
|
||||
var name = user?.Name ?? "Unknown";
|
||||
list ??= [];
|
||||
```
|
||||
|
||||
### Type Hints (REQUIRED)
|
||||
## Immutability (Critical)
|
||||
|
||||
```python
|
||||
# GOOD: Full type annotations
|
||||
from typing import Optional
|
||||
from pathlib import Path
|
||||
from dataclasses import dataclass
|
||||
```csharp
|
||||
// GOOD: Create new objects
|
||||
public record User(string Name, int Age)
|
||||
{
|
||||
public User WithName(string newName) => this with { Name = newName };
|
||||
}
|
||||
|
||||
@dataclass
|
||||
class InferenceResult:
|
||||
document_id: str
|
||||
fields: dict[str, str]
|
||||
confidence: dict[str, float]
|
||||
processing_time_ms: float
|
||||
// GOOD: Immutable collections
|
||||
public IReadOnlyList<string> GetNames() => _names.AsReadOnly();
|
||||
|
||||
def process_document(
|
||||
pdf_path: Path,
|
||||
confidence_threshold: float = 0.5
|
||||
) -> InferenceResult:
|
||||
"""Process PDF and return extracted fields."""
|
||||
...
|
||||
|
||||
# BAD: No type hints
|
||||
def process_document(pdf_path, confidence_threshold=0.5):
|
||||
...
|
||||
// BAD: Mutation
|
||||
public void UpdateUser(User user, string name)
|
||||
{
|
||||
user.Name = name; // MUTATION!
|
||||
}
|
||||
```
|
||||
|
||||
### Immutability Pattern (CRITICAL)
|
||||
## Error Handling
|
||||
|
||||
```python
|
||||
# GOOD: Create new objects, don't mutate
|
||||
def update_fields(fields: dict[str, str], updates: dict[str, str]) -> dict[str, str]:
|
||||
return {**fields, **updates}
|
||||
```csharp
|
||||
// Domain exceptions
|
||||
public class NotFoundException(string resource, Guid id)
|
||||
: Exception($"{resource} not found: {id}");
|
||||
|
||||
def add_item(items: list[str], new_item: str) -> list[str]:
|
||||
return [*items, new_item]
|
||||
// Comprehensive handling
|
||||
public async Task<Document> LoadAsync(Guid id, CancellationToken ct)
|
||||
{
|
||||
try
|
||||
{
|
||||
var doc = await _repo.GetByIdAsync(id, ct);
|
||||
return doc ?? throw new NotFoundException("Document", id);
|
||||
}
|
||||
catch (Exception ex) when (ex is not NotFoundException)
|
||||
{
|
||||
_logger.LogError(ex, "Failed to load document {Id}", id);
|
||||
throw;
|
||||
}
|
||||
}
|
||||
|
||||
# BAD: Direct mutation
|
||||
def update_fields(fields: dict[str, str], updates: dict[str, str]) -> dict[str, str]:
|
||||
fields.update(updates) # MUTATION!
|
||||
return fields
|
||||
|
||||
def add_item(items: list[str], new_item: str) -> list[str]:
|
||||
items.append(new_item) # MUTATION!
|
||||
return items
|
||||
// Result pattern for expected failures
|
||||
public Result<Document> Validate(CreateRequest request) =>
|
||||
string.IsNullOrEmpty(request.Name)
|
||||
? Result<Document>.Fail("Name required")
|
||||
: Result<Document>.Ok(new Document(request.Name));
|
||||
```
|
||||
|
||||
### Error Handling
|
||||
## Async/Await
|
||||
|
||||
```python
|
||||
import logging
|
||||
```csharp
|
||||
// Always pass CancellationToken
|
||||
public async Task<Document> GetAsync(Guid id, CancellationToken ct)
|
||||
|
||||
logger = logging.getLogger(__name__)
|
||||
// Use ConfigureAwait(false) in libraries
|
||||
await _client.GetAsync(url, ct).ConfigureAwait(false);
|
||||
|
||||
# GOOD: Comprehensive error handling with logging
|
||||
def load_model(model_path: Path) -> Model:
|
||||
"""Load YOLO model from path."""
|
||||
try:
|
||||
if not model_path.exists():
|
||||
raise FileNotFoundError(f"Model not found: {model_path}")
|
||||
// Avoid async void
|
||||
public async Task ProcessAsync() { } // Good
|
||||
public async void Process() { } // Bad
|
||||
|
||||
model = YOLO(str(model_path))
|
||||
logger.info(f"Model loaded: {model_path}")
|
||||
return model
|
||||
except Exception as e:
|
||||
logger.error(f"Failed to load model: {e}")
|
||||
raise RuntimeError(f"Model loading failed: {model_path}") from e
|
||||
|
||||
# BAD: No error handling
|
||||
def load_model(model_path):
|
||||
return YOLO(str(model_path))
|
||||
|
||||
# BAD: Bare except
|
||||
def load_model(model_path):
|
||||
try:
|
||||
return YOLO(str(model_path))
|
||||
except: # Never use bare except!
|
||||
return None
|
||||
// Parallel when independent
|
||||
var tasks = ids.Select(id => GetAsync(id, ct));
|
||||
var results = await Task.WhenAll(tasks);
|
||||
```
|
||||
|
||||
### Async Best Practices
|
||||
## LINQ Best Practices
|
||||
|
||||
```python
|
||||
import asyncio
|
||||
```csharp
|
||||
// Prefer method syntax for complex queries
|
||||
var result = documents
|
||||
.Where(d => d.Status == "Active")
|
||||
.OrderByDescending(d => d.CreatedAt)
|
||||
.Select(d => new DocumentDto(d.Id, d.Name, d.CreatedAt))
|
||||
.Take(10);
|
||||
|
||||
# GOOD: Parallel execution when possible
|
||||
async def process_batch(pdf_paths: list[Path]) -> list[InferenceResult]:
|
||||
tasks = [process_document(path) for path in pdf_paths]
|
||||
results = await asyncio.gather(*tasks, return_exceptions=True)
|
||||
// Use Any() instead of Count() > 0
|
||||
if (documents.Any(d => d.IsValid)) { }
|
||||
|
||||
# Handle exceptions
|
||||
valid_results = []
|
||||
for path, result in zip(pdf_paths, results):
|
||||
if isinstance(result, Exception):
|
||||
logger.error(f"Failed to process {path}: {result}")
|
||||
else:
|
||||
valid_results.append(result)
|
||||
return valid_results
|
||||
|
||||
# BAD: Sequential when unnecessary
|
||||
async def process_batch(pdf_paths: list[Path]) -> list[InferenceResult]:
|
||||
results = []
|
||||
for path in pdf_paths:
|
||||
result = await process_document(path)
|
||||
results.append(result)
|
||||
return results
|
||||
```
|
||||
|
||||
### Context Managers
|
||||
|
||||
```python
|
||||
from contextlib import contextmanager
|
||||
from pathlib import Path
|
||||
import tempfile
|
||||
|
||||
# GOOD: Proper resource management
|
||||
@contextmanager
|
||||
def temp_pdf_copy(pdf_path: Path):
|
||||
"""Create temporary copy of PDF for processing."""
|
||||
with tempfile.NamedTemporaryFile(suffix=".pdf", delete=False) as tmp:
|
||||
tmp.write(pdf_path.read_bytes())
|
||||
tmp_path = Path(tmp.name)
|
||||
try:
|
||||
yield tmp_path
|
||||
finally:
|
||||
tmp_path.unlink(missing_ok=True)
|
||||
|
||||
# Usage
|
||||
with temp_pdf_copy(original_pdf) as tmp_pdf:
|
||||
result = process_pdf(tmp_pdf)
|
||||
```
|
||||
|
||||
## FastAPI Best Practices
|
||||
|
||||
### Route Structure
|
||||
|
||||
```python
|
||||
from fastapi import APIRouter, HTTPException, Depends, Query, File, UploadFile
|
||||
from pydantic import BaseModel
|
||||
|
||||
router = APIRouter(prefix="/api/v1", tags=["inference"])
|
||||
|
||||
class InferenceResponse(BaseModel):
|
||||
success: bool
|
||||
document_id: str
|
||||
fields: dict[str, str]
|
||||
confidence: dict[str, float]
|
||||
processing_time_ms: float
|
||||
|
||||
@router.post("/infer", response_model=InferenceResponse)
|
||||
async def infer_document(
|
||||
file: UploadFile = File(...),
|
||||
confidence_threshold: float = Query(0.5, ge=0.0, le=1.0)
|
||||
) -> InferenceResponse:
|
||||
"""Process invoice PDF and extract fields."""
|
||||
if not file.filename.endswith(".pdf"):
|
||||
raise HTTPException(status_code=400, detail="Only PDF files accepted")
|
||||
|
||||
result = await inference_service.process(file, confidence_threshold)
|
||||
return InferenceResponse(
|
||||
success=True,
|
||||
document_id=result.document_id,
|
||||
fields=result.fields,
|
||||
confidence=result.confidence,
|
||||
processing_time_ms=result.processing_time_ms
|
||||
)
|
||||
```
|
||||
|
||||
### Input Validation with Pydantic
|
||||
|
||||
```python
|
||||
from pydantic import BaseModel, Field, field_validator
|
||||
from datetime import date
|
||||
import re
|
||||
|
||||
class InvoiceData(BaseModel):
|
||||
invoice_number: str = Field(..., min_length=1, max_length=50)
|
||||
invoice_date: date
|
||||
amount: float = Field(..., gt=0)
|
||||
bankgiro: str | None = None
|
||||
ocr_number: str | None = None
|
||||
|
||||
@field_validator("bankgiro")
|
||||
@classmethod
|
||||
def validate_bankgiro(cls, v: str | None) -> str | None:
|
||||
if v is None:
|
||||
return None
|
||||
# Bankgiro: 7-8 digits
|
||||
cleaned = re.sub(r"[^0-9]", "", v)
|
||||
if not (7 <= len(cleaned) <= 8):
|
||||
raise ValueError("Bankgiro must be 7-8 digits")
|
||||
return cleaned
|
||||
|
||||
@field_validator("ocr_number")
|
||||
@classmethod
|
||||
def validate_ocr(cls, v: str | None) -> str | None:
|
||||
if v is None:
|
||||
return None
|
||||
# OCR: 2-25 digits
|
||||
cleaned = re.sub(r"[^0-9]", "", v)
|
||||
if not (2 <= len(cleaned) <= 25):
|
||||
raise ValueError("OCR must be 2-25 digits")
|
||||
return cleaned
|
||||
```
|
||||
|
||||
### Response Format
|
||||
|
||||
```python
|
||||
from pydantic import BaseModel
|
||||
from typing import Generic, TypeVar
|
||||
|
||||
T = TypeVar("T")
|
||||
|
||||
class ApiResponse(BaseModel, Generic[T]):
|
||||
success: bool
|
||||
data: T | None = None
|
||||
error: str | None = None
|
||||
meta: dict | None = None
|
||||
|
||||
# Success response
|
||||
return ApiResponse(
|
||||
success=True,
|
||||
data=result,
|
||||
meta={"processing_time_ms": elapsed_ms}
|
||||
)
|
||||
|
||||
# Error response
|
||||
return ApiResponse(
|
||||
success=False,
|
||||
error="Invalid PDF format"
|
||||
)
|
||||
// Avoid multiple enumerations
|
||||
var list = documents.ToList(); // Materialize once
|
||||
var count = list.Count;
|
||||
var first = list.FirstOrDefault();
|
||||
```
|
||||
|
||||
## File Organization
|
||||
|
||||
### Project Structure
|
||||
|
||||
```
|
||||
src/
|
||||
├── cli/ # Command-line interfaces
|
||||
│ ├── autolabel.py
|
||||
│ ├── train.py
|
||||
│ └── infer.py
|
||||
├── pdf/ # PDF processing
|
||||
│ ├── extractor.py
|
||||
│ └── renderer.py
|
||||
├── ocr/ # OCR processing
|
||||
│ ├── paddle_ocr.py
|
||||
│ └── machine_code_parser.py
|
||||
├── inference/ # Inference pipeline
|
||||
│ ├── pipeline.py
|
||||
│ ├── yolo_detector.py
|
||||
│ └── field_extractor.py
|
||||
├── normalize/ # Field normalization
|
||||
│ ├── base.py
|
||||
│ ├── date_normalizer.py
|
||||
│ └── amount_normalizer.py
|
||||
├── web/ # FastAPI application
|
||||
│ ├── app.py
|
||||
│ ├── routes.py
|
||||
│ ├── services.py
|
||||
│ └── schemas.py
|
||||
└── utils/ # Shared utilities
|
||||
├── validators.py
|
||||
├── text_cleaner.py
|
||||
└── logging.py
|
||||
tests/ # Mirror of src structure
|
||||
├── test_pdf/
|
||||
├── test_ocr/
|
||||
└── test_inference/
|
||||
Domain/ # Entities, value objects
|
||||
Application/ # Use cases, DTOs, interfaces
|
||||
Infrastructure/ # EF Core, external services
|
||||
Api/ # Controllers, middleware
|
||||
tests/
|
||||
Unit/
|
||||
Integration/
|
||||
```
|
||||
|
||||
### File Naming
|
||||
**Guidelines:**
|
||||
- Max 800 lines per file (typical 200-400)
|
||||
- Max 50 lines per method
|
||||
- One class per file (except nested)
|
||||
- Group by feature, not by type
|
||||
|
||||
```
|
||||
src/ocr/paddle_ocr.py # snake_case for modules
|
||||
src/inference/yolo_detector.py # snake_case for modules
|
||||
tests/test_paddle_ocr.py # test_ prefix for tests
|
||||
config.py # snake_case for config
|
||||
## Code Smells
|
||||
|
||||
```csharp
|
||||
// BAD: Deep nesting
|
||||
if (doc != null)
|
||||
if (doc.IsValid)
|
||||
if (doc.HasFields)
|
||||
// ...
|
||||
|
||||
// GOOD: Early returns
|
||||
if (doc is null) return null;
|
||||
if (!doc.IsValid) return null;
|
||||
if (!doc.HasFields) return null;
|
||||
// ...
|
||||
|
||||
// BAD: Magic numbers
|
||||
if (confidence > 0.5) { }
|
||||
|
||||
// GOOD: Named constants
|
||||
private const double ConfidenceThreshold = 0.5;
|
||||
if (confidence > ConfidenceThreshold) { }
|
||||
```
|
||||
|
||||
### Module Size Guidelines
|
||||
## Logging
|
||||
|
||||
- **Maximum**: 800 lines per file
|
||||
- **Typical**: 200-400 lines per file
|
||||
- **Functions**: Max 50 lines each
|
||||
- Extract utilities when modules grow too large
|
||||
```csharp
|
||||
// Structured logging with templates
|
||||
_logger.LogInformation("Processing document {DocumentId}", docId);
|
||||
_logger.LogError(ex, "Failed to process {DocumentId}", docId);
|
||||
|
||||
## Comments & Documentation
|
||||
|
||||
### When to Comment
|
||||
|
||||
```python
|
||||
# GOOD: Explain WHY, not WHAT
|
||||
# Swedish Bankgiro uses Luhn algorithm with weight [1,2,1,2...]
|
||||
def validate_bankgiro_checksum(bankgiro: str) -> bool:
|
||||
...
|
||||
|
||||
# Payment line format: 7 groups separated by #, checksum at end
|
||||
def parse_payment_line(line: str) -> PaymentLineData:
|
||||
...
|
||||
|
||||
# BAD: Stating the obvious
|
||||
# Increment counter by 1
|
||||
count += 1
|
||||
|
||||
# Set name to user's name
|
||||
name = user.name
|
||||
// Appropriate levels
|
||||
LogDebug // Development details
|
||||
LogInformation // Normal operations
|
||||
LogWarning // Potential issues
|
||||
LogError // Errors with exceptions
|
||||
```
|
||||
|
||||
### Docstrings for Public APIs
|
||||
## Testing (AAA Pattern)
|
||||
|
||||
```python
|
||||
def extract_invoice_fields(
|
||||
pdf_path: Path,
|
||||
confidence_threshold: float = 0.5,
|
||||
use_gpu: bool = True
|
||||
) -> InferenceResult:
|
||||
"""Extract structured fields from Swedish invoice PDF.
|
||||
```csharp
|
||||
[Fact]
|
||||
public async Task GetById_WithValidId_ReturnsDocument()
|
||||
{
|
||||
// Arrange
|
||||
var repo = Substitute.For<IRepository<Document>>();
|
||||
repo.GetByIdAsync(Arg.Any<Guid>(), Arg.Any<CancellationToken>())
|
||||
.Returns(new Document("Test"));
|
||||
var service = new DocumentService(repo);
|
||||
|
||||
Uses YOLOv11 for field detection and PaddleOCR for text extraction.
|
||||
Applies field-specific normalization and validation.
|
||||
// Act
|
||||
var result = await service.GetAsync(Guid.NewGuid(), CancellationToken.None);
|
||||
|
||||
Args:
|
||||
pdf_path: Path to the invoice PDF file.
|
||||
confidence_threshold: Minimum confidence for field detection (0.0-1.0).
|
||||
use_gpu: Whether to use GPU acceleration.
|
||||
|
||||
Returns:
|
||||
InferenceResult containing extracted fields and confidence scores.
|
||||
|
||||
Raises:
|
||||
FileNotFoundError: If PDF file doesn't exist.
|
||||
ProcessingError: If OCR or detection fails.
|
||||
|
||||
Example:
|
||||
>>> result = extract_invoice_fields(Path("invoice.pdf"))
|
||||
>>> print(result.fields["invoice_number"])
|
||||
"INV-2024-001"
|
||||
"""
|
||||
...
|
||||
// Assert
|
||||
result.Should().NotBeNull();
|
||||
result!.Name.Should().Be("Test");
|
||||
}
|
||||
```
|
||||
|
||||
## Performance Best Practices
|
||||
## Key Rules
|
||||
|
||||
### Caching
|
||||
|
||||
```python
|
||||
from functools import lru_cache
|
||||
from cachetools import TTLCache
|
||||
|
||||
# Static data: LRU cache
|
||||
@lru_cache(maxsize=100)
|
||||
def get_field_config(field_name: str) -> FieldConfig:
|
||||
"""Load field configuration (cached)."""
|
||||
return load_config(field_name)
|
||||
|
||||
# Dynamic data: TTL cache
|
||||
_document_cache = TTLCache(maxsize=1000, ttl=300) # 5 minutes
|
||||
|
||||
def get_document_cached(doc_id: str) -> Document | None:
|
||||
if doc_id in _document_cache:
|
||||
return _document_cache[doc_id]
|
||||
|
||||
doc = repo.find_by_id(doc_id)
|
||||
if doc:
|
||||
_document_cache[doc_id] = doc
|
||||
return doc
|
||||
```
|
||||
|
||||
### Database Queries
|
||||
|
||||
```python
|
||||
# GOOD: Select only needed columns
|
||||
cur.execute("""
|
||||
SELECT id, status, fields->>'invoice_number'
|
||||
FROM documents
|
||||
WHERE status = %s
|
||||
LIMIT %s
|
||||
""", ('processed', 10))
|
||||
|
||||
# BAD: Select everything
|
||||
cur.execute("SELECT * FROM documents")
|
||||
|
||||
# GOOD: Batch operations
|
||||
cur.executemany(
|
||||
"INSERT INTO labels (doc_id, field, value) VALUES (%s, %s, %s)",
|
||||
[(doc_id, f, v) for f, v in fields.items()]
|
||||
)
|
||||
|
||||
# BAD: Individual inserts in loop
|
||||
for field, value in fields.items():
|
||||
cur.execute("INSERT INTO labels ...", (doc_id, field, value))
|
||||
```
|
||||
|
||||
### Lazy Loading
|
||||
|
||||
```python
|
||||
class InferencePipeline:
|
||||
def __init__(self, model_path: Path):
|
||||
self.model_path = model_path
|
||||
self._model: YOLO | None = None
|
||||
self._ocr: PaddleOCR | None = None
|
||||
|
||||
@property
|
||||
def model(self) -> YOLO:
|
||||
"""Lazy load YOLO model."""
|
||||
if self._model is None:
|
||||
self._model = YOLO(str(self.model_path))
|
||||
return self._model
|
||||
|
||||
@property
|
||||
def ocr(self) -> PaddleOCR:
|
||||
"""Lazy load PaddleOCR."""
|
||||
if self._ocr is None:
|
||||
self._ocr = PaddleOCR(use_angle_cls=True, lang="latin")
|
||||
return self._ocr
|
||||
```
|
||||
|
||||
## Testing Standards
|
||||
|
||||
### Test Structure (AAA Pattern)
|
||||
|
||||
```python
|
||||
def test_extract_bankgiro_valid():
|
||||
# Arrange
|
||||
text = "Bankgiro: 123-4567"
|
||||
|
||||
# Act
|
||||
result = extract_bankgiro(text)
|
||||
|
||||
# Assert
|
||||
assert result == "1234567"
|
||||
|
||||
def test_extract_bankgiro_invalid_returns_none():
|
||||
# Arrange
|
||||
text = "No bankgiro here"
|
||||
|
||||
# Act
|
||||
result = extract_bankgiro(text)
|
||||
|
||||
# Assert
|
||||
assert result is None
|
||||
```
|
||||
|
||||
### Test Naming
|
||||
|
||||
```python
|
||||
# GOOD: Descriptive test names
|
||||
def test_parse_payment_line_extracts_all_fields(): ...
|
||||
def test_parse_payment_line_handles_missing_checksum(): ...
|
||||
def test_validate_ocr_returns_false_for_invalid_checksum(): ...
|
||||
|
||||
# BAD: Vague test names
|
||||
def test_parse(): ...
|
||||
def test_works(): ...
|
||||
def test_payment_line(): ...
|
||||
```
|
||||
|
||||
### Fixtures
|
||||
|
||||
```python
|
||||
import pytest
|
||||
from pathlib import Path
|
||||
|
||||
@pytest.fixture
|
||||
def sample_invoice_pdf(tmp_path: Path) -> Path:
|
||||
"""Create sample invoice PDF for testing."""
|
||||
pdf_path = tmp_path / "invoice.pdf"
|
||||
# Create test PDF...
|
||||
return pdf_path
|
||||
|
||||
@pytest.fixture
|
||||
def inference_pipeline(sample_model_path: Path) -> InferencePipeline:
|
||||
"""Create inference pipeline with test model."""
|
||||
return InferencePipeline(sample_model_path)
|
||||
|
||||
def test_process_invoice(inference_pipeline, sample_invoice_pdf):
|
||||
result = inference_pipeline.process(sample_invoice_pdf)
|
||||
assert result.fields.get("invoice_number") is not None
|
||||
```
|
||||
|
||||
## Code Smell Detection
|
||||
|
||||
### 1. Long Functions
|
||||
|
||||
```python
|
||||
# BAD: Function > 50 lines
|
||||
def process_document():
|
||||
# 100 lines of code...
|
||||
|
||||
# GOOD: Split into smaller functions
|
||||
def process_document(pdf_path: Path) -> InferenceResult:
|
||||
image = render_pdf(pdf_path)
|
||||
detections = detect_fields(image)
|
||||
ocr_results = extract_text(image, detections)
|
||||
fields = normalize_fields(ocr_results)
|
||||
return build_result(fields)
|
||||
```
|
||||
|
||||
### 2. Deep Nesting
|
||||
|
||||
```python
|
||||
# BAD: 5+ levels of nesting
|
||||
if document:
|
||||
if document.is_valid:
|
||||
if document.has_fields:
|
||||
if field in document.fields:
|
||||
if document.fields[field]:
|
||||
# Do something
|
||||
|
||||
# GOOD: Early returns
|
||||
if not document:
|
||||
return None
|
||||
if not document.is_valid:
|
||||
return None
|
||||
if not document.has_fields:
|
||||
return None
|
||||
if field not in document.fields:
|
||||
return None
|
||||
if not document.fields[field]:
|
||||
return None
|
||||
|
||||
# Do something
|
||||
```
|
||||
|
||||
### 3. Magic Numbers
|
||||
|
||||
```python
|
||||
# BAD: Unexplained numbers
|
||||
if confidence > 0.5:
|
||||
...
|
||||
time.sleep(3)
|
||||
|
||||
# GOOD: Named constants
|
||||
CONFIDENCE_THRESHOLD = 0.5
|
||||
RETRY_DELAY_SECONDS = 3
|
||||
|
||||
if confidence > CONFIDENCE_THRESHOLD:
|
||||
...
|
||||
time.sleep(RETRY_DELAY_SECONDS)
|
||||
```
|
||||
|
||||
### 4. Mutable Default Arguments
|
||||
|
||||
```python
|
||||
# BAD: Mutable default argument
|
||||
def process_fields(fields: list = []): # DANGEROUS!
|
||||
fields.append("new_field")
|
||||
return fields
|
||||
|
||||
# GOOD: Use None as default
|
||||
def process_fields(fields: list | None = None) -> list:
|
||||
if fields is None:
|
||||
fields = []
|
||||
return [*fields, "new_field"]
|
||||
```
|
||||
|
||||
## Logging Standards
|
||||
|
||||
```python
|
||||
import logging
|
||||
|
||||
# Module-level logger
|
||||
logger = logging.getLogger(__name__)
|
||||
|
||||
# GOOD: Appropriate log levels
|
||||
logger.debug("Processing document: %s", doc_id)
|
||||
logger.info("Document processed successfully: %s", doc_id)
|
||||
logger.warning("Low confidence score: %.2f", confidence)
|
||||
logger.error("Failed to process document: %s", error)
|
||||
|
||||
# GOOD: Structured logging with extra data
|
||||
logger.info(
|
||||
"Inference complete",
|
||||
extra={
|
||||
"document_id": doc_id,
|
||||
"field_count": len(fields),
|
||||
"processing_time_ms": elapsed_ms
|
||||
}
|
||||
)
|
||||
|
||||
# BAD: Using print()
|
||||
print(f"Processing {doc_id}") # Never in production!
|
||||
```
|
||||
|
||||
**Remember**: Code quality is not negotiable. Clear, maintainable Python code with proper type hints enables confident development and refactoring.
|
||||
- Always use `CancellationToken` for async methods
|
||||
- Prefer `records` for DTOs and immutable data
|
||||
- Use `IReadOnlyList<T>` for return types
|
||||
- Never use `async void` (except event handlers)
|
||||
- Always handle `null` with pattern matching or null operators
|
||||
- Use structured logging, never `Console.WriteLine`
|
||||
|
||||
@@ -1,314 +1,274 @@
|
||||
# Backend Development Patterns
|
||||
# .NET Development Best Practices
|
||||
|
||||
Backend architecture patterns for Python/FastAPI/PostgreSQL applications.
|
||||
|
||||
## API Design
|
||||
|
||||
### RESTful Structure
|
||||
## Project Structure
|
||||
|
||||
```
|
||||
GET /api/v1/documents # List
|
||||
GET /api/v1/documents/{id} # Get
|
||||
POST /api/v1/documents # Create
|
||||
PUT /api/v1/documents/{id} # Replace
|
||||
PATCH /api/v1/documents/{id} # Update
|
||||
DELETE /api/v1/documents/{id} # Delete
|
||||
|
||||
GET /api/v1/documents?status=processed&sort=created_at&limit=20&offset=0
|
||||
src/
|
||||
Domain/ # Entities, value objects, domain events
|
||||
Application/ # Use cases, DTOs, interfaces
|
||||
Infrastructure/ # EF Core, external services
|
||||
Api/ # Controllers, middleware, filters
|
||||
tests/
|
||||
Unit/
|
||||
Integration/
|
||||
```
|
||||
|
||||
### FastAPI Route Pattern
|
||||
## Code Style
|
||||
|
||||
```python
|
||||
from fastapi import APIRouter, HTTPException, Depends, Query, File, UploadFile
|
||||
from pydantic import BaseModel
|
||||
```csharp
|
||||
// Use records for DTOs and value objects
|
||||
public sealed record CreateDocumentRequest(string Name, string Type);
|
||||
|
||||
router = APIRouter(prefix="/api/v1", tags=["inference"])
|
||||
// Use primary constructors
|
||||
public class DocumentService(IRepository<Document> repo, ILogger<DocumentService> logger)
|
||||
{
|
||||
public async Task<Document?> GetAsync(Guid id, CancellationToken ct) =>
|
||||
await repo.GetByIdAsync(id, ct);
|
||||
}
|
||||
|
||||
@router.post("/infer", response_model=ApiResponse[InferenceResult])
|
||||
async def infer_document(
|
||||
file: UploadFile = File(...),
|
||||
confidence_threshold: float = Query(0.5, ge=0, le=1),
|
||||
service: InferenceService = Depends(get_inference_service)
|
||||
) -> ApiResponse[InferenceResult]:
|
||||
result = await service.process(file, confidence_threshold)
|
||||
return ApiResponse(success=True, data=result)
|
||||
// Prefer expression body for simple methods
|
||||
public Document? FindById(Guid id) => _documents.FirstOrDefault(d => d.Id == id);
|
||||
|
||||
// Use collection expressions
|
||||
int[] numbers = [1, 2, 3];
|
||||
List<string> names = ["Alice", "Bob"];
|
||||
```
|
||||
|
||||
### Consistent Response Schema
|
||||
## Async/Await
|
||||
|
||||
```python
|
||||
from typing import Generic, TypeVar
|
||||
T = TypeVar('T')
|
||||
```csharp
|
||||
// Always pass CancellationToken
|
||||
public async Task<Document> GetAsync(Guid id, CancellationToken ct)
|
||||
|
||||
class ApiResponse(BaseModel, Generic[T]):
|
||||
success: bool
|
||||
data: T | None = None
|
||||
error: str | None = None
|
||||
meta: dict | None = None
|
||||
// Use ConfigureAwait(false) in libraries
|
||||
await _httpClient.GetAsync(url, ct).ConfigureAwait(false);
|
||||
|
||||
// Avoid async void (except event handlers)
|
||||
public async Task ProcessAsync() { } // Good
|
||||
public async void Process() { } // Bad
|
||||
|
||||
// Use ValueTask for hot paths with frequent sync completion
|
||||
public ValueTask<int> GetCachedCountAsync()
|
||||
```
|
||||
|
||||
## Core Patterns
|
||||
## Dependency Injection
|
||||
|
||||
### Repository Pattern
|
||||
```csharp
|
||||
// Register by interface
|
||||
builder.Services.AddScoped<IDocumentService, DocumentService>();
|
||||
|
||||
```python
|
||||
from typing import Protocol
|
||||
// Use Options pattern for configuration
|
||||
builder.Services.Configure<AppSettings>(builder.Configuration.GetSection("App"));
|
||||
|
||||
class DocumentRepository(Protocol):
|
||||
def find_all(self, filters: dict | None = None) -> list[Document]: ...
|
||||
def find_by_id(self, id: str) -> Document | None: ...
|
||||
def create(self, data: dict) -> Document: ...
|
||||
def update(self, id: str, data: dict) -> Document: ...
|
||||
def delete(self, id: str) -> None: ...
|
||||
public class MyService(IOptions<AppSettings> options)
|
||||
{
|
||||
private readonly AppSettings _settings = options.Value;
|
||||
}
|
||||
|
||||
// Avoid service locator pattern
|
||||
// Bad: var service = serviceProvider.GetService<IMyService>();
|
||||
// Good: Constructor injection
|
||||
```
|
||||
|
||||
### Service Layer
|
||||
## Entity Framework Core
|
||||
|
||||
```python
|
||||
class InferenceService:
|
||||
def __init__(self, model_path: str, use_gpu: bool = True):
|
||||
self.pipeline = InferencePipeline(model_path=model_path, use_gpu=use_gpu)
|
||||
```csharp
|
||||
// Always use AsNoTracking for read-only queries
|
||||
await _context.Documents.AsNoTracking().ToListAsync(ct);
|
||||
|
||||
async def process(self, file: UploadFile, confidence_threshold: float) -> InferenceResult:
|
||||
temp_path = self._save_temp_file(file)
|
||||
try:
|
||||
return self.pipeline.process_pdf(temp_path)
|
||||
finally:
|
||||
temp_path.unlink(missing_ok=True)
|
||||
```
|
||||
// Use projection to select only needed fields
|
||||
await _context.Documents
|
||||
.Where(d => d.Status == "Active")
|
||||
.Select(d => new DocumentDto(d.Id, d.Name))
|
||||
.ToListAsync(ct);
|
||||
|
||||
### Dependency Injection
|
||||
// Prevent N+1 with Include or projection
|
||||
await _context.Documents.Include(d => d.Labels).ToListAsync(ct);
|
||||
|
||||
```python
|
||||
from functools import lru_cache
|
||||
from pydantic_settings import BaseSettings
|
||||
// Use explicit transactions for multiple operations
|
||||
await using var tx = await _context.Database.BeginTransactionAsync(ct);
|
||||
|
||||
class Settings(BaseSettings):
|
||||
db_host: str = "localhost"
|
||||
db_password: str
|
||||
model_path: str = "runs/train/invoice_fields/weights/best.pt"
|
||||
class Config:
|
||||
env_file = ".env"
|
||||
|
||||
@lru_cache()
|
||||
def get_settings() -> Settings:
|
||||
return Settings()
|
||||
|
||||
def get_inference_service(settings: Settings = Depends(get_settings)) -> InferenceService:
|
||||
return InferenceService(model_path=settings.model_path)
|
||||
```
|
||||
|
||||
## Database Patterns
|
||||
|
||||
### Connection Pooling
|
||||
|
||||
```python
|
||||
from psycopg2 import pool
|
||||
from contextlib import contextmanager
|
||||
|
||||
db_pool = pool.ThreadedConnectionPool(minconn=2, maxconn=10, **db_config)
|
||||
|
||||
@contextmanager
|
||||
def get_db_connection():
|
||||
conn = db_pool.getconn()
|
||||
try:
|
||||
yield conn
|
||||
finally:
|
||||
db_pool.putconn(conn)
|
||||
```
|
||||
|
||||
### Query Optimization
|
||||
|
||||
```python
|
||||
# GOOD: Select only needed columns
|
||||
cur.execute("""
|
||||
SELECT id, status, fields->>'InvoiceNumber' as invoice_number
|
||||
FROM documents WHERE status = %s
|
||||
ORDER BY created_at DESC LIMIT %s
|
||||
""", ('processed', 10))
|
||||
|
||||
# BAD: SELECT * FROM documents
|
||||
```
|
||||
|
||||
### N+1 Prevention
|
||||
|
||||
```python
|
||||
# BAD: N+1 queries
|
||||
for doc in documents:
|
||||
doc.labels = get_labels(doc.id) # N queries
|
||||
|
||||
# GOOD: Batch fetch with JOIN
|
||||
cur.execute("""
|
||||
SELECT d.id, d.status, array_agg(l.label) as labels
|
||||
FROM documents d
|
||||
LEFT JOIN document_labels l ON d.id = l.document_id
|
||||
GROUP BY d.id, d.status
|
||||
""")
|
||||
```
|
||||
|
||||
### Transaction Pattern
|
||||
|
||||
```python
|
||||
def create_document_with_labels(doc_data: dict, labels: list[dict]) -> str:
|
||||
with get_db_connection() as conn:
|
||||
try:
|
||||
with conn.cursor() as cur:
|
||||
cur.execute("INSERT INTO documents ... RETURNING id", ...)
|
||||
doc_id = cur.fetchone()[0]
|
||||
for label in labels:
|
||||
cur.execute("INSERT INTO document_labels ...", ...)
|
||||
conn.commit()
|
||||
return doc_id
|
||||
except Exception:
|
||||
conn.rollback()
|
||||
raise
|
||||
```
|
||||
|
||||
## Caching
|
||||
|
||||
```python
|
||||
from cachetools import TTLCache
|
||||
|
||||
_cache = TTLCache(maxsize=1000, ttl=300)
|
||||
|
||||
def get_document_cached(doc_id: str) -> Document | None:
|
||||
if doc_id in _cache:
|
||||
return _cache[doc_id]
|
||||
doc = repo.find_by_id(doc_id)
|
||||
if doc:
|
||||
_cache[doc_id] = doc
|
||||
return doc
|
||||
// Configure entities with IEntityTypeConfiguration
|
||||
public class DocumentConfiguration : IEntityTypeConfiguration<Document>
|
||||
{
|
||||
public void Configure(EntityTypeBuilder<Document> builder)
|
||||
{
|
||||
builder.HasKey(d => d.Id);
|
||||
builder.Property(d => d.Name).HasMaxLength(200).IsRequired();
|
||||
builder.HasIndex(d => d.Status);
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
## Error Handling
|
||||
|
||||
### Exception Hierarchy
|
||||
```csharp
|
||||
// Create domain-specific exceptions
|
||||
public class NotFoundException(string resource, Guid id)
|
||||
: Exception($"{resource} not found: {id}");
|
||||
|
||||
```python
|
||||
class AppError(Exception):
|
||||
def __init__(self, message: str, status_code: int = 500):
|
||||
self.message = message
|
||||
self.status_code = status_code
|
||||
// Use global exception handler
|
||||
public class GlobalExceptionHandler(ILogger<GlobalExceptionHandler> logger) : IExceptionHandler
|
||||
{
|
||||
public async ValueTask<bool> TryHandleAsync(HttpContext ctx, Exception ex, CancellationToken ct)
|
||||
{
|
||||
logger.LogError(ex, "Error: {Message}", ex.Message);
|
||||
ctx.Response.StatusCode = ex is NotFoundException ? 404 : 500;
|
||||
await ctx.Response.WriteAsJsonAsync(new { error = ex.Message }, ct);
|
||||
return true;
|
||||
}
|
||||
}
|
||||
|
||||
class NotFoundError(AppError):
|
||||
def __init__(self, resource: str, id: str):
|
||||
super().__init__(f"{resource} not found: {id}", 404)
|
||||
|
||||
class ValidationError(AppError):
|
||||
def __init__(self, message: str):
|
||||
super().__init__(message, 400)
|
||||
// Use Result pattern for expected failures
|
||||
public Result<Document> Validate(CreateRequest request) =>
|
||||
string.IsNullOrEmpty(request.Name)
|
||||
? Result<Document>.Fail("Name is required")
|
||||
: Result<Document>.Ok(new Document(request.Name));
|
||||
```
|
||||
|
||||
### FastAPI Exception Handler
|
||||
## Validation
|
||||
|
||||
```python
|
||||
@app.exception_handler(AppError)
|
||||
async def app_error_handler(request: Request, exc: AppError):
|
||||
return JSONResponse(status_code=exc.status_code, content={"success": False, "error": exc.message})
|
||||
```csharp
|
||||
// Use FluentValidation
|
||||
public class CreateDocumentValidator : AbstractValidator<CreateDocumentRequest>
|
||||
{
|
||||
public CreateDocumentValidator()
|
||||
{
|
||||
RuleFor(x => x.Name).NotEmpty().MaximumLength(200);
|
||||
RuleFor(x => x.Type).Must(BeValidType).WithMessage("Invalid document type");
|
||||
}
|
||||
}
|
||||
|
||||
@app.exception_handler(Exception)
|
||||
async def generic_error_handler(request: Request, exc: Exception):
|
||||
logger.error(f"Unexpected error: {exc}", exc_info=True)
|
||||
return JSONResponse(status_code=500, content={"success": False, "error": "Internal server error"})
|
||||
// Or use Data Annotations for simple cases
|
||||
public record CreateRequest(
|
||||
[Required, MaxLength(200)] string Name,
|
||||
[Range(1, 100)] int Quantity);
|
||||
```
|
||||
|
||||
### Retry with Backoff
|
||||
## Logging
|
||||
|
||||
```python
|
||||
async def retry_with_backoff(fn, max_retries: int = 3, base_delay: float = 1.0):
|
||||
last_error = None
|
||||
for attempt in range(max_retries):
|
||||
try:
|
||||
return await fn() if asyncio.iscoroutinefunction(fn) else fn()
|
||||
except Exception as e:
|
||||
last_error = e
|
||||
if attempt < max_retries - 1:
|
||||
await asyncio.sleep(base_delay * (2 ** attempt))
|
||||
raise last_error
|
||||
```csharp
|
||||
// Use structured logging with templates
|
||||
logger.LogInformation("Processing document {DocumentId} for user {UserId}", docId, userId);
|
||||
|
||||
// Use appropriate log levels
|
||||
logger.LogDebug("Cache hit for key {Key}", key); // Development details
|
||||
logger.LogInformation("Document {Id} created", id); // Normal operations
|
||||
logger.LogWarning("Retry attempt {Attempt} for {Op}", n, op); // Potential issues
|
||||
logger.LogError(ex, "Failed to process {DocumentId}", id); // Errors
|
||||
|
||||
// Configure log filtering in appsettings
|
||||
{
|
||||
"Logging": {
|
||||
"LogLevel": {
|
||||
"Default": "Information",
|
||||
"Microsoft.AspNetCore": "Warning",
|
||||
"Microsoft.EntityFrameworkCore": "Warning"
|
||||
}
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
## Rate Limiting
|
||||
## API Design
|
||||
|
||||
```python
|
||||
from time import time
|
||||
from collections import defaultdict
|
||||
```csharp
|
||||
[ApiController]
|
||||
[Route("api/v1/[controller]")]
|
||||
public class DocumentsController(IDocumentService service) : ControllerBase
|
||||
{
|
||||
[HttpGet("{id:guid}")]
|
||||
[ProducesResponseType<Document>(200)]
|
||||
[ProducesResponseType(404)]
|
||||
public async Task<IActionResult> Get(Guid id, CancellationToken ct)
|
||||
{
|
||||
var doc = await service.GetAsync(id, ct);
|
||||
return doc is null ? NotFound() : Ok(doc);
|
||||
}
|
||||
|
||||
class RateLimiter:
|
||||
def __init__(self):
|
||||
self.requests: dict[str, list[float]] = defaultdict(list)
|
||||
|
||||
def check_limit(self, identifier: str, max_requests: int, window_sec: int) -> bool:
|
||||
now = time()
|
||||
self.requests[identifier] = [t for t in self.requests[identifier] if now - t < window_sec]
|
||||
if len(self.requests[identifier]) >= max_requests:
|
||||
return False
|
||||
self.requests[identifier].append(now)
|
||||
return True
|
||||
|
||||
limiter = RateLimiter()
|
||||
|
||||
@app.middleware("http")
|
||||
async def rate_limit_middleware(request: Request, call_next):
|
||||
ip = request.client.host
|
||||
if not limiter.check_limit(ip, max_requests=100, window_sec=60):
|
||||
return JSONResponse(status_code=429, content={"error": "Rate limit exceeded"})
|
||||
return await call_next(request)
|
||||
[HttpPost]
|
||||
public async Task<IActionResult> Create(CreateRequest request, CancellationToken ct)
|
||||
{
|
||||
var doc = await service.CreateAsync(request, ct);
|
||||
return CreatedAtAction(nameof(Get), new { id = doc.Id }, doc);
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
## Logging & Middleware
|
||||
## Testing
|
||||
|
||||
### Request Logging
|
||||
```csharp
|
||||
// Use descriptive test names
|
||||
[Fact]
|
||||
public async Task GetById_WithValidId_ReturnsDocument()
|
||||
{
|
||||
// Arrange
|
||||
var repo = Substitute.For<IRepository<Document>>();
|
||||
repo.GetByIdAsync(Arg.Any<Guid>(), Arg.Any<CancellationToken>())
|
||||
.Returns(new Document("Test"));
|
||||
var service = new DocumentService(repo);
|
||||
|
||||
```python
|
||||
@app.middleware("http")
|
||||
async def log_requests(request: Request, call_next):
|
||||
request_id = str(uuid.uuid4())[:8]
|
||||
start_time = time.time()
|
||||
logger.info(f"[{request_id}] {request.method} {request.url.path}")
|
||||
response = await call_next(request)
|
||||
duration_ms = (time.time() - start_time) * 1000
|
||||
logger.info(f"[{request_id}] Completed {response.status_code} in {duration_ms:.2f}ms")
|
||||
return response
|
||||
// Act
|
||||
var result = await service.GetAsync(Guid.NewGuid(), CancellationToken.None);
|
||||
|
||||
// Assert
|
||||
result.Should().NotBeNull();
|
||||
result!.Name.Should().Be("Test");
|
||||
}
|
||||
|
||||
// Use WebApplicationFactory for integration tests
|
||||
public class ApiTests(WebApplicationFactory<Program> factory) : IClassFixture<WebApplicationFactory<Program>>
|
||||
{
|
||||
[Fact]
|
||||
public async Task GetDocuments_ReturnsSuccess()
|
||||
{
|
||||
var client = factory.CreateClient();
|
||||
var response = await client.GetAsync("/api/v1/documents");
|
||||
response.StatusCode.Should().Be(HttpStatusCode.OK);
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
### Structured Logging
|
||||
## Performance
|
||||
|
||||
```python
|
||||
class JSONFormatter(logging.Formatter):
|
||||
def format(self, record):
|
||||
return json.dumps({
|
||||
"timestamp": datetime.utcnow().isoformat(),
|
||||
"level": record.levelname,
|
||||
"message": record.getMessage(),
|
||||
"module": record.module,
|
||||
})
|
||||
```csharp
|
||||
// Use IMemoryCache for frequently accessed data
|
||||
public class CachedService(IMemoryCache cache, IRepository<Document> repo)
|
||||
{
|
||||
public async Task<Document?> GetAsync(Guid id, CancellationToken ct) =>
|
||||
await cache.GetOrCreateAsync($"doc:{id}", async entry =>
|
||||
{
|
||||
entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(5);
|
||||
return await repo.GetByIdAsync(id, ct);
|
||||
});
|
||||
}
|
||||
|
||||
// Use pagination for large collections
|
||||
public async Task<PagedResult<Document>> GetPagedAsync(int page, int size, CancellationToken ct) =>
|
||||
new(
|
||||
await _context.Documents.Skip((page - 1) * size).Take(size).ToListAsync(ct),
|
||||
await _context.Documents.CountAsync(ct)
|
||||
);
|
||||
|
||||
// Use IAsyncEnumerable for streaming large datasets
|
||||
public async IAsyncEnumerable<Document> StreamAllAsync([EnumeratorCancellation] CancellationToken ct)
|
||||
{
|
||||
await foreach (var doc in _context.Documents.AsAsyncEnumerable().WithCancellation(ct))
|
||||
yield return doc;
|
||||
}
|
||||
```
|
||||
|
||||
## Background Tasks
|
||||
## Security
|
||||
|
||||
```python
|
||||
from fastapi import BackgroundTasks
|
||||
```csharp
|
||||
// Never hardcode secrets
|
||||
var apiKey = builder.Configuration["ApiKey"]; // From environment/secrets
|
||||
|
||||
def send_notification(document_id: str, status: str):
|
||||
logger.info(f"Notification: {document_id} -> {status}")
|
||||
// Use parameterized queries (EF Core does this automatically)
|
||||
// Bad: $"SELECT * FROM Users WHERE Id = {id}"
|
||||
// Good: _context.Users.Where(u => u.Id == id)
|
||||
|
||||
@router.post("/infer")
|
||||
async def infer(file: UploadFile, background_tasks: BackgroundTasks):
|
||||
result = await process_document(file)
|
||||
background_tasks.add_task(send_notification, result.document_id, "completed")
|
||||
return result
|
||||
// Validate and sanitize all inputs
|
||||
// Use HTTPS in production
|
||||
// Implement rate limiting
|
||||
builder.Services.AddRateLimiter(options => { ... });
|
||||
```
|
||||
|
||||
## Key Principles
|
||||
|
||||
- Repository pattern: Abstract data access
|
||||
- Service layer: Business logic separated from routes
|
||||
- Dependency injection via `Depends()`
|
||||
- Connection pooling for database
|
||||
- Parameterized queries only (no f-strings in SQL)
|
||||
- Batch fetch to prevent N+1
|
||||
- Consistent `ApiResponse[T]` format
|
||||
- Exception hierarchy with proper status codes
|
||||
- Rate limit by IP
|
||||
- Structured logging with request ID
|
||||
@@ -1,665 +1,234 @@
|
||||
---
|
||||
name: coding-standards
|
||||
description: Universal coding standards, best practices, and patterns for Python, FastAPI, and data processing development.
|
||||
description: .NET/C# coding standards and best practices.
|
||||
---
|
||||
|
||||
# Coding Standards & Best Practices
|
||||
# .NET Coding Standards
|
||||
|
||||
Python coding standards for the Invoice Master project.
|
||||
## Core Principles
|
||||
|
||||
## Code Quality Principles
|
||||
- **Readability First** - Clear names, self-documenting code
|
||||
- **KISS** - Simplest solution that works
|
||||
- **DRY** - Extract common logic, avoid copy-paste
|
||||
- **YAGNI** - Don't build features before needed
|
||||
|
||||
### 1. Readability First
|
||||
- Code is read more than written
|
||||
- Clear variable and function names
|
||||
- Self-documenting code preferred over comments
|
||||
- Consistent formatting (follow PEP 8)
|
||||
## Naming Conventions
|
||||
|
||||
### 2. KISS (Keep It Simple, Stupid)
|
||||
- Simplest solution that works
|
||||
- Avoid over-engineering
|
||||
- No premature optimization
|
||||
- Easy to understand > clever code
|
||||
```csharp
|
||||
// PascalCase: Types, methods, properties, public fields
|
||||
public class DocumentService { }
|
||||
public async Task<Document> GetByIdAsync(Guid id) { }
|
||||
public string InvoiceNumber { get; init; }
|
||||
|
||||
### 3. DRY (Don't Repeat Yourself)
|
||||
- Extract common logic into functions
|
||||
- Create reusable utilities
|
||||
- Share modules across the codebase
|
||||
- Avoid copy-paste programming
|
||||
// camelCase: Parameters, local variables, private fields with underscore
|
||||
private readonly ILogger<DocumentService> _logger;
|
||||
public void Process(string documentId, int pageCount) { }
|
||||
|
||||
### 4. YAGNI (You Aren't Gonna Need It)
|
||||
- Don't build features before they're needed
|
||||
- Avoid speculative generality
|
||||
- Add complexity only when required
|
||||
- Start simple, refactor when needed
|
||||
// Interfaces: I prefix
|
||||
public interface IDocumentRepository { }
|
||||
|
||||
## Python Standards
|
||||
|
||||
### Variable Naming
|
||||
|
||||
```python
|
||||
# GOOD: Descriptive names
|
||||
invoice_number = "INV-2024-001"
|
||||
is_valid_document = True
|
||||
total_confidence_score = 0.95
|
||||
|
||||
# BAD: Unclear names
|
||||
inv = "INV-2024-001"
|
||||
flag = True
|
||||
x = 0.95
|
||||
// Async methods: Async suffix
|
||||
public async Task<Document> LoadAsync(CancellationToken ct)
|
||||
```
|
||||
|
||||
### Function Naming
|
||||
## Modern C# Features
|
||||
|
||||
```python
|
||||
# GOOD: Verb-noun pattern with type hints
|
||||
def extract_invoice_fields(pdf_path: Path) -> dict[str, str]:
|
||||
"""Extract fields from invoice PDF."""
|
||||
...
|
||||
```csharp
|
||||
// Records for DTOs and value objects
|
||||
public sealed record CreateDocumentRequest(string Name, string Type);
|
||||
public sealed record DocumentDto(Guid Id, string Name, DateTime CreatedAt);
|
||||
|
||||
def calculate_confidence(predictions: list[float]) -> float:
|
||||
"""Calculate average confidence score."""
|
||||
...
|
||||
// Primary constructors
|
||||
public class DocumentService(IRepository<Document> repo, ILogger<DocumentService> logger)
|
||||
{
|
||||
public async Task<Document?> GetAsync(Guid id, CancellationToken ct) =>
|
||||
await repo.GetByIdAsync(id, ct);
|
||||
}
|
||||
|
||||
def is_valid_bankgiro(value: str) -> bool:
|
||||
"""Check if value is valid Bankgiro number."""
|
||||
...
|
||||
// Pattern matching
|
||||
var message = result switch
|
||||
{
|
||||
{ IsSuccess: true, Value: var doc } => $"Found: {doc.Name}",
|
||||
{ Error: var err } => $"Error: {err}",
|
||||
_ => "Unknown"
|
||||
};
|
||||
|
||||
# BAD: Unclear or noun-only
|
||||
def invoice(path):
|
||||
...
|
||||
// Collection expressions
|
||||
int[] numbers = [1, 2, 3];
|
||||
List<string> names = ["Alice", "Bob"];
|
||||
|
||||
def confidence(p):
|
||||
...
|
||||
|
||||
def bankgiro(v):
|
||||
...
|
||||
// Null coalescing
|
||||
var name = user?.Name ?? "Unknown";
|
||||
list ??= [];
|
||||
```
|
||||
|
||||
### Type Hints (REQUIRED)
|
||||
## Immutability (Critical)
|
||||
|
||||
```python
|
||||
# GOOD: Full type annotations
|
||||
from typing import Optional
|
||||
from pathlib import Path
|
||||
from dataclasses import dataclass
|
||||
```csharp
|
||||
// GOOD: Create new objects
|
||||
public record User(string Name, int Age)
|
||||
{
|
||||
public User WithName(string newName) => this with { Name = newName };
|
||||
}
|
||||
|
||||
@dataclass
|
||||
class InferenceResult:
|
||||
document_id: str
|
||||
fields: dict[str, str]
|
||||
confidence: dict[str, float]
|
||||
processing_time_ms: float
|
||||
// GOOD: Immutable collections
|
||||
public IReadOnlyList<string> GetNames() => _names.AsReadOnly();
|
||||
|
||||
def process_document(
|
||||
pdf_path: Path,
|
||||
confidence_threshold: float = 0.5
|
||||
) -> InferenceResult:
|
||||
"""Process PDF and return extracted fields."""
|
||||
...
|
||||
|
||||
# BAD: No type hints
|
||||
def process_document(pdf_path, confidence_threshold=0.5):
|
||||
...
|
||||
// BAD: Mutation
|
||||
public void UpdateUser(User user, string name)
|
||||
{
|
||||
user.Name = name; // MUTATION!
|
||||
}
|
||||
```
|
||||
|
||||
### Immutability Pattern (CRITICAL)
|
||||
## Error Handling
|
||||
|
||||
```python
|
||||
# GOOD: Create new objects, don't mutate
|
||||
def update_fields(fields: dict[str, str], updates: dict[str, str]) -> dict[str, str]:
|
||||
return {**fields, **updates}
|
||||
```csharp
|
||||
// Domain exceptions
|
||||
public class NotFoundException(string resource, Guid id)
|
||||
: Exception($"{resource} not found: {id}");
|
||||
|
||||
def add_item(items: list[str], new_item: str) -> list[str]:
|
||||
return [*items, new_item]
|
||||
// Comprehensive handling
|
||||
public async Task<Document> LoadAsync(Guid id, CancellationToken ct)
|
||||
{
|
||||
try
|
||||
{
|
||||
var doc = await _repo.GetByIdAsync(id, ct);
|
||||
return doc ?? throw new NotFoundException("Document", id);
|
||||
}
|
||||
catch (Exception ex) when (ex is not NotFoundException)
|
||||
{
|
||||
_logger.LogError(ex, "Failed to load document {Id}", id);
|
||||
throw;
|
||||
}
|
||||
}
|
||||
|
||||
# BAD: Direct mutation
|
||||
def update_fields(fields: dict[str, str], updates: dict[str, str]) -> dict[str, str]:
|
||||
fields.update(updates) # MUTATION!
|
||||
return fields
|
||||
|
||||
def add_item(items: list[str], new_item: str) -> list[str]:
|
||||
items.append(new_item) # MUTATION!
|
||||
return items
|
||||
// Result pattern for expected failures
|
||||
public Result<Document> Validate(CreateRequest request) =>
|
||||
string.IsNullOrEmpty(request.Name)
|
||||
? Result<Document>.Fail("Name required")
|
||||
: Result<Document>.Ok(new Document(request.Name));
|
||||
```
|
||||
|
||||
### Error Handling
|
||||
## Async/Await
|
||||
|
||||
```python
|
||||
import logging
|
||||
```csharp
|
||||
// Always pass CancellationToken
|
||||
public async Task<Document> GetAsync(Guid id, CancellationToken ct)
|
||||
|
||||
logger = logging.getLogger(__name__)
|
||||
// Use ConfigureAwait(false) in libraries
|
||||
await _client.GetAsync(url, ct).ConfigureAwait(false);
|
||||
|
||||
# GOOD: Comprehensive error handling with logging
|
||||
def load_model(model_path: Path) -> Model:
|
||||
"""Load YOLO model from path."""
|
||||
try:
|
||||
if not model_path.exists():
|
||||
raise FileNotFoundError(f"Model not found: {model_path}")
|
||||
// Avoid async void
|
||||
public async Task ProcessAsync() { } // Good
|
||||
public async void Process() { } // Bad
|
||||
|
||||
model = YOLO(str(model_path))
|
||||
logger.info(f"Model loaded: {model_path}")
|
||||
return model
|
||||
except Exception as e:
|
||||
logger.error(f"Failed to load model: {e}")
|
||||
raise RuntimeError(f"Model loading failed: {model_path}") from e
|
||||
|
||||
# BAD: No error handling
|
||||
def load_model(model_path):
|
||||
return YOLO(str(model_path))
|
||||
|
||||
# BAD: Bare except
|
||||
def load_model(model_path):
|
||||
try:
|
||||
return YOLO(str(model_path))
|
||||
except: # Never use bare except!
|
||||
return None
|
||||
// Parallel when independent
|
||||
var tasks = ids.Select(id => GetAsync(id, ct));
|
||||
var results = await Task.WhenAll(tasks);
|
||||
```
|
||||
|
||||
### Async Best Practices
|
||||
## LINQ Best Practices
|
||||
|
||||
```python
|
||||
import asyncio
|
||||
```csharp
|
||||
// Prefer method syntax for complex queries
|
||||
var result = documents
|
||||
.Where(d => d.Status == "Active")
|
||||
.OrderByDescending(d => d.CreatedAt)
|
||||
.Select(d => new DocumentDto(d.Id, d.Name, d.CreatedAt))
|
||||
.Take(10);
|
||||
|
||||
# GOOD: Parallel execution when possible
|
||||
async def process_batch(pdf_paths: list[Path]) -> list[InferenceResult]:
|
||||
tasks = [process_document(path) for path in pdf_paths]
|
||||
results = await asyncio.gather(*tasks, return_exceptions=True)
|
||||
// Use Any() instead of Count() > 0
|
||||
if (documents.Any(d => d.IsValid)) { }
|
||||
|
||||
# Handle exceptions
|
||||
valid_results = []
|
||||
for path, result in zip(pdf_paths, results):
|
||||
if isinstance(result, Exception):
|
||||
logger.error(f"Failed to process {path}: {result}")
|
||||
else:
|
||||
valid_results.append(result)
|
||||
return valid_results
|
||||
|
||||
# BAD: Sequential when unnecessary
|
||||
async def process_batch(pdf_paths: list[Path]) -> list[InferenceResult]:
|
||||
results = []
|
||||
for path in pdf_paths:
|
||||
result = await process_document(path)
|
||||
results.append(result)
|
||||
return results
|
||||
```
|
||||
|
||||
### Context Managers
|
||||
|
||||
```python
|
||||
from contextlib import contextmanager
|
||||
from pathlib import Path
|
||||
import tempfile
|
||||
|
||||
# GOOD: Proper resource management
|
||||
@contextmanager
|
||||
def temp_pdf_copy(pdf_path: Path):
|
||||
"""Create temporary copy of PDF for processing."""
|
||||
with tempfile.NamedTemporaryFile(suffix=".pdf", delete=False) as tmp:
|
||||
tmp.write(pdf_path.read_bytes())
|
||||
tmp_path = Path(tmp.name)
|
||||
try:
|
||||
yield tmp_path
|
||||
finally:
|
||||
tmp_path.unlink(missing_ok=True)
|
||||
|
||||
# Usage
|
||||
with temp_pdf_copy(original_pdf) as tmp_pdf:
|
||||
result = process_pdf(tmp_pdf)
|
||||
```
|
||||
|
||||
## FastAPI Best Practices
|
||||
|
||||
### Route Structure
|
||||
|
||||
```python
|
||||
from fastapi import APIRouter, HTTPException, Depends, Query, File, UploadFile
|
||||
from pydantic import BaseModel
|
||||
|
||||
router = APIRouter(prefix="/api/v1", tags=["inference"])
|
||||
|
||||
class InferenceResponse(BaseModel):
|
||||
success: bool
|
||||
document_id: str
|
||||
fields: dict[str, str]
|
||||
confidence: dict[str, float]
|
||||
processing_time_ms: float
|
||||
|
||||
@router.post("/infer", response_model=InferenceResponse)
|
||||
async def infer_document(
|
||||
file: UploadFile = File(...),
|
||||
confidence_threshold: float = Query(0.5, ge=0.0, le=1.0)
|
||||
) -> InferenceResponse:
|
||||
"""Process invoice PDF and extract fields."""
|
||||
if not file.filename.endswith(".pdf"):
|
||||
raise HTTPException(status_code=400, detail="Only PDF files accepted")
|
||||
|
||||
result = await inference_service.process(file, confidence_threshold)
|
||||
return InferenceResponse(
|
||||
success=True,
|
||||
document_id=result.document_id,
|
||||
fields=result.fields,
|
||||
confidence=result.confidence,
|
||||
processing_time_ms=result.processing_time_ms
|
||||
)
|
||||
```
|
||||
|
||||
### Input Validation with Pydantic
|
||||
|
||||
```python
|
||||
from pydantic import BaseModel, Field, field_validator
|
||||
from datetime import date
|
||||
import re
|
||||
|
||||
class InvoiceData(BaseModel):
|
||||
invoice_number: str = Field(..., min_length=1, max_length=50)
|
||||
invoice_date: date
|
||||
amount: float = Field(..., gt=0)
|
||||
bankgiro: str | None = None
|
||||
ocr_number: str | None = None
|
||||
|
||||
@field_validator("bankgiro")
|
||||
@classmethod
|
||||
def validate_bankgiro(cls, v: str | None) -> str | None:
|
||||
if v is None:
|
||||
return None
|
||||
# Bankgiro: 7-8 digits
|
||||
cleaned = re.sub(r"[^0-9]", "", v)
|
||||
if not (7 <= len(cleaned) <= 8):
|
||||
raise ValueError("Bankgiro must be 7-8 digits")
|
||||
return cleaned
|
||||
|
||||
@field_validator("ocr_number")
|
||||
@classmethod
|
||||
def validate_ocr(cls, v: str | None) -> str | None:
|
||||
if v is None:
|
||||
return None
|
||||
# OCR: 2-25 digits
|
||||
cleaned = re.sub(r"[^0-9]", "", v)
|
||||
if not (2 <= len(cleaned) <= 25):
|
||||
raise ValueError("OCR must be 2-25 digits")
|
||||
return cleaned
|
||||
```
|
||||
|
||||
### Response Format
|
||||
|
||||
```python
|
||||
from pydantic import BaseModel
|
||||
from typing import Generic, TypeVar
|
||||
|
||||
T = TypeVar("T")
|
||||
|
||||
class ApiResponse(BaseModel, Generic[T]):
|
||||
success: bool
|
||||
data: T | None = None
|
||||
error: str | None = None
|
||||
meta: dict | None = None
|
||||
|
||||
# Success response
|
||||
return ApiResponse(
|
||||
success=True,
|
||||
data=result,
|
||||
meta={"processing_time_ms": elapsed_ms}
|
||||
)
|
||||
|
||||
# Error response
|
||||
return ApiResponse(
|
||||
success=False,
|
||||
error="Invalid PDF format"
|
||||
)
|
||||
// Avoid multiple enumerations
|
||||
var list = documents.ToList(); // Materialize once
|
||||
var count = list.Count;
|
||||
var first = list.FirstOrDefault();
|
||||
```
|
||||
|
||||
## File Organization
|
||||
|
||||
### Project Structure
|
||||
|
||||
```
|
||||
src/
|
||||
├── cli/ # Command-line interfaces
|
||||
│ ├── autolabel.py
|
||||
│ ├── train.py
|
||||
│ └── infer.py
|
||||
├── pdf/ # PDF processing
|
||||
│ ├── extractor.py
|
||||
│ └── renderer.py
|
||||
├── ocr/ # OCR processing
|
||||
│ ├── paddle_ocr.py
|
||||
│ └── machine_code_parser.py
|
||||
├── inference/ # Inference pipeline
|
||||
│ ├── pipeline.py
|
||||
│ ├── yolo_detector.py
|
||||
│ └── field_extractor.py
|
||||
├── normalize/ # Field normalization
|
||||
│ ├── base.py
|
||||
│ ├── date_normalizer.py
|
||||
│ └── amount_normalizer.py
|
||||
├── web/ # FastAPI application
|
||||
│ ├── app.py
|
||||
│ ├── routes.py
|
||||
│ ├── services.py
|
||||
│ └── schemas.py
|
||||
└── utils/ # Shared utilities
|
||||
├── validators.py
|
||||
├── text_cleaner.py
|
||||
└── logging.py
|
||||
tests/ # Mirror of src structure
|
||||
├── test_pdf/
|
||||
├── test_ocr/
|
||||
└── test_inference/
|
||||
Domain/ # Entities, value objects
|
||||
Application/ # Use cases, DTOs, interfaces
|
||||
Infrastructure/ # EF Core, external services
|
||||
Api/ # Controllers, middleware
|
||||
tests/
|
||||
Unit/
|
||||
Integration/
|
||||
```
|
||||
|
||||
### File Naming
|
||||
**Guidelines:**
|
||||
- Max 800 lines per file (typical 200-400)
|
||||
- Max 50 lines per method
|
||||
- One class per file (except nested)
|
||||
- Group by feature, not by type
|
||||
|
||||
```
|
||||
src/ocr/paddle_ocr.py # snake_case for modules
|
||||
src/inference/yolo_detector.py # snake_case for modules
|
||||
tests/test_paddle_ocr.py # test_ prefix for tests
|
||||
config.py # snake_case for config
|
||||
## Code Smells
|
||||
|
||||
```csharp
|
||||
// BAD: Deep nesting
|
||||
if (doc != null)
|
||||
if (doc.IsValid)
|
||||
if (doc.HasFields)
|
||||
// ...
|
||||
|
||||
// GOOD: Early returns
|
||||
if (doc is null) return null;
|
||||
if (!doc.IsValid) return null;
|
||||
if (!doc.HasFields) return null;
|
||||
// ...
|
||||
|
||||
// BAD: Magic numbers
|
||||
if (confidence > 0.5) { }
|
||||
|
||||
// GOOD: Named constants
|
||||
private const double ConfidenceThreshold = 0.5;
|
||||
if (confidence > ConfidenceThreshold) { }
|
||||
```
|
||||
|
||||
### Module Size Guidelines
|
||||
## Logging
|
||||
|
||||
- **Maximum**: 800 lines per file
|
||||
- **Typical**: 200-400 lines per file
|
||||
- **Functions**: Max 50 lines each
|
||||
- Extract utilities when modules grow too large
|
||||
```csharp
|
||||
// Structured logging with templates
|
||||
_logger.LogInformation("Processing document {DocumentId}", docId);
|
||||
_logger.LogError(ex, "Failed to process {DocumentId}", docId);
|
||||
|
||||
## Comments & Documentation
|
||||
|
||||
### When to Comment
|
||||
|
||||
```python
|
||||
# GOOD: Explain WHY, not WHAT
|
||||
# Swedish Bankgiro uses Luhn algorithm with weight [1,2,1,2...]
|
||||
def validate_bankgiro_checksum(bankgiro: str) -> bool:
|
||||
...
|
||||
|
||||
# Payment line format: 7 groups separated by #, checksum at end
|
||||
def parse_payment_line(line: str) -> PaymentLineData:
|
||||
...
|
||||
|
||||
# BAD: Stating the obvious
|
||||
# Increment counter by 1
|
||||
count += 1
|
||||
|
||||
# Set name to user's name
|
||||
name = user.name
|
||||
// Appropriate levels
|
||||
LogDebug // Development details
|
||||
LogInformation // Normal operations
|
||||
LogWarning // Potential issues
|
||||
LogError // Errors with exceptions
|
||||
```
|
||||
|
||||
### Docstrings for Public APIs
|
||||
## Testing (AAA Pattern)
|
||||
|
||||
```python
|
||||
def extract_invoice_fields(
|
||||
pdf_path: Path,
|
||||
confidence_threshold: float = 0.5,
|
||||
use_gpu: bool = True
|
||||
) -> InferenceResult:
|
||||
"""Extract structured fields from Swedish invoice PDF.
|
||||
```csharp
|
||||
[Fact]
|
||||
public async Task GetById_WithValidId_ReturnsDocument()
|
||||
{
|
||||
// Arrange
|
||||
var repo = Substitute.For<IRepository<Document>>();
|
||||
repo.GetByIdAsync(Arg.Any<Guid>(), Arg.Any<CancellationToken>())
|
||||
.Returns(new Document("Test"));
|
||||
var service = new DocumentService(repo);
|
||||
|
||||
Uses YOLOv11 for field detection and PaddleOCR for text extraction.
|
||||
Applies field-specific normalization and validation.
|
||||
// Act
|
||||
var result = await service.GetAsync(Guid.NewGuid(), CancellationToken.None);
|
||||
|
||||
Args:
|
||||
pdf_path: Path to the invoice PDF file.
|
||||
confidence_threshold: Minimum confidence for field detection (0.0-1.0).
|
||||
use_gpu: Whether to use GPU acceleration.
|
||||
|
||||
Returns:
|
||||
InferenceResult containing extracted fields and confidence scores.
|
||||
|
||||
Raises:
|
||||
FileNotFoundError: If PDF file doesn't exist.
|
||||
ProcessingError: If OCR or detection fails.
|
||||
|
||||
Example:
|
||||
>>> result = extract_invoice_fields(Path("invoice.pdf"))
|
||||
>>> print(result.fields["invoice_number"])
|
||||
"INV-2024-001"
|
||||
"""
|
||||
...
|
||||
// Assert
|
||||
result.Should().NotBeNull();
|
||||
result!.Name.Should().Be("Test");
|
||||
}
|
||||
```
|
||||
|
||||
## Performance Best Practices
|
||||
## Key Rules
|
||||
|
||||
### Caching
|
||||
|
||||
```python
|
||||
from functools import lru_cache
|
||||
from cachetools import TTLCache
|
||||
|
||||
# Static data: LRU cache
|
||||
@lru_cache(maxsize=100)
|
||||
def get_field_config(field_name: str) -> FieldConfig:
|
||||
"""Load field configuration (cached)."""
|
||||
return load_config(field_name)
|
||||
|
||||
# Dynamic data: TTL cache
|
||||
_document_cache = TTLCache(maxsize=1000, ttl=300) # 5 minutes
|
||||
|
||||
def get_document_cached(doc_id: str) -> Document | None:
|
||||
if doc_id in _document_cache:
|
||||
return _document_cache[doc_id]
|
||||
|
||||
doc = repo.find_by_id(doc_id)
|
||||
if doc:
|
||||
_document_cache[doc_id] = doc
|
||||
return doc
|
||||
```
|
||||
|
||||
### Database Queries
|
||||
|
||||
```python
|
||||
# GOOD: Select only needed columns
|
||||
cur.execute("""
|
||||
SELECT id, status, fields->>'invoice_number'
|
||||
FROM documents
|
||||
WHERE status = %s
|
||||
LIMIT %s
|
||||
""", ('processed', 10))
|
||||
|
||||
# BAD: Select everything
|
||||
cur.execute("SELECT * FROM documents")
|
||||
|
||||
# GOOD: Batch operations
|
||||
cur.executemany(
|
||||
"INSERT INTO labels (doc_id, field, value) VALUES (%s, %s, %s)",
|
||||
[(doc_id, f, v) for f, v in fields.items()]
|
||||
)
|
||||
|
||||
# BAD: Individual inserts in loop
|
||||
for field, value in fields.items():
|
||||
cur.execute("INSERT INTO labels ...", (doc_id, field, value))
|
||||
```
|
||||
|
||||
### Lazy Loading
|
||||
|
||||
```python
|
||||
class InferencePipeline:
|
||||
def __init__(self, model_path: Path):
|
||||
self.model_path = model_path
|
||||
self._model: YOLO | None = None
|
||||
self._ocr: PaddleOCR | None = None
|
||||
|
||||
@property
|
||||
def model(self) -> YOLO:
|
||||
"""Lazy load YOLO model."""
|
||||
if self._model is None:
|
||||
self._model = YOLO(str(self.model_path))
|
||||
return self._model
|
||||
|
||||
@property
|
||||
def ocr(self) -> PaddleOCR:
|
||||
"""Lazy load PaddleOCR."""
|
||||
if self._ocr is None:
|
||||
self._ocr = PaddleOCR(use_angle_cls=True, lang="latin")
|
||||
return self._ocr
|
||||
```
|
||||
|
||||
## Testing Standards
|
||||
|
||||
### Test Structure (AAA Pattern)
|
||||
|
||||
```python
|
||||
def test_extract_bankgiro_valid():
|
||||
# Arrange
|
||||
text = "Bankgiro: 123-4567"
|
||||
|
||||
# Act
|
||||
result = extract_bankgiro(text)
|
||||
|
||||
# Assert
|
||||
assert result == "1234567"
|
||||
|
||||
def test_extract_bankgiro_invalid_returns_none():
|
||||
# Arrange
|
||||
text = "No bankgiro here"
|
||||
|
||||
# Act
|
||||
result = extract_bankgiro(text)
|
||||
|
||||
# Assert
|
||||
assert result is None
|
||||
```
|
||||
|
||||
### Test Naming
|
||||
|
||||
```python
|
||||
# GOOD: Descriptive test names
|
||||
def test_parse_payment_line_extracts_all_fields(): ...
|
||||
def test_parse_payment_line_handles_missing_checksum(): ...
|
||||
def test_validate_ocr_returns_false_for_invalid_checksum(): ...
|
||||
|
||||
# BAD: Vague test names
|
||||
def test_parse(): ...
|
||||
def test_works(): ...
|
||||
def test_payment_line(): ...
|
||||
```
|
||||
|
||||
### Fixtures
|
||||
|
||||
```python
|
||||
import pytest
|
||||
from pathlib import Path
|
||||
|
||||
@pytest.fixture
|
||||
def sample_invoice_pdf(tmp_path: Path) -> Path:
|
||||
"""Create sample invoice PDF for testing."""
|
||||
pdf_path = tmp_path / "invoice.pdf"
|
||||
# Create test PDF...
|
||||
return pdf_path
|
||||
|
||||
@pytest.fixture
|
||||
def inference_pipeline(sample_model_path: Path) -> InferencePipeline:
|
||||
"""Create inference pipeline with test model."""
|
||||
return InferencePipeline(sample_model_path)
|
||||
|
||||
def test_process_invoice(inference_pipeline, sample_invoice_pdf):
|
||||
result = inference_pipeline.process(sample_invoice_pdf)
|
||||
assert result.fields.get("invoice_number") is not None
|
||||
```
|
||||
|
||||
## Code Smell Detection
|
||||
|
||||
### 1. Long Functions
|
||||
|
||||
```python
|
||||
# BAD: Function > 50 lines
|
||||
def process_document():
|
||||
# 100 lines of code...
|
||||
|
||||
# GOOD: Split into smaller functions
|
||||
def process_document(pdf_path: Path) -> InferenceResult:
|
||||
image = render_pdf(pdf_path)
|
||||
detections = detect_fields(image)
|
||||
ocr_results = extract_text(image, detections)
|
||||
fields = normalize_fields(ocr_results)
|
||||
return build_result(fields)
|
||||
```
|
||||
|
||||
### 2. Deep Nesting
|
||||
|
||||
```python
|
||||
# BAD: 5+ levels of nesting
|
||||
if document:
|
||||
if document.is_valid:
|
||||
if document.has_fields:
|
||||
if field in document.fields:
|
||||
if document.fields[field]:
|
||||
# Do something
|
||||
|
||||
# GOOD: Early returns
|
||||
if not document:
|
||||
return None
|
||||
if not document.is_valid:
|
||||
return None
|
||||
if not document.has_fields:
|
||||
return None
|
||||
if field not in document.fields:
|
||||
return None
|
||||
if not document.fields[field]:
|
||||
return None
|
||||
|
||||
# Do something
|
||||
```
|
||||
|
||||
### 3. Magic Numbers
|
||||
|
||||
```python
|
||||
# BAD: Unexplained numbers
|
||||
if confidence > 0.5:
|
||||
...
|
||||
time.sleep(3)
|
||||
|
||||
# GOOD: Named constants
|
||||
CONFIDENCE_THRESHOLD = 0.5
|
||||
RETRY_DELAY_SECONDS = 3
|
||||
|
||||
if confidence > CONFIDENCE_THRESHOLD:
|
||||
...
|
||||
time.sleep(RETRY_DELAY_SECONDS)
|
||||
```
|
||||
|
||||
### 4. Mutable Default Arguments
|
||||
|
||||
```python
|
||||
# BAD: Mutable default argument
|
||||
def process_fields(fields: list = []): # DANGEROUS!
|
||||
fields.append("new_field")
|
||||
return fields
|
||||
|
||||
# GOOD: Use None as default
|
||||
def process_fields(fields: list | None = None) -> list:
|
||||
if fields is None:
|
||||
fields = []
|
||||
return [*fields, "new_field"]
|
||||
```
|
||||
|
||||
## Logging Standards
|
||||
|
||||
```python
|
||||
import logging
|
||||
|
||||
# Module-level logger
|
||||
logger = logging.getLogger(__name__)
|
||||
|
||||
# GOOD: Appropriate log levels
|
||||
logger.debug("Processing document: %s", doc_id)
|
||||
logger.info("Document processed successfully: %s", doc_id)
|
||||
logger.warning("Low confidence score: %.2f", confidence)
|
||||
logger.error("Failed to process document: %s", error)
|
||||
|
||||
# GOOD: Structured logging with extra data
|
||||
logger.info(
|
||||
"Inference complete",
|
||||
extra={
|
||||
"document_id": doc_id,
|
||||
"field_count": len(fields),
|
||||
"processing_time_ms": elapsed_ms
|
||||
}
|
||||
)
|
||||
|
||||
# BAD: Using print()
|
||||
print(f"Processing {doc_id}") # Never in production!
|
||||
```
|
||||
|
||||
**Remember**: Code quality is not negotiable. Clear, maintainable Python code with proper type hints enables confident development and refactoring.
|
||||
- Always use `CancellationToken` for async methods
|
||||
- Prefer `records` for DTOs and immutable data
|
||||
- Use `IReadOnlyList<T>` for return types
|
||||
- Never use `async void` (except event handlers)
|
||||
- Always handle `null` with pattern matching or null operators
|
||||
- Use structured logging, never `Console.WriteLine`
|
||||
|
||||
Reference in New Issue
Block a user