FastAPI Backend Development

ETPS Architecture

• FastAPI with async/await patterns
• SQLAlchemy ORM for database models (backend/db/models.py)
• Pydantic schemas (backend/schemas/)
• Service layer pattern (backend/services/)
• Config loaded from backend/config/config.yaml

Key Files

• backend/main.py - Application entry point
• backend/routers/ - API endpoint definitions
• backend/services/ - Business logic
• backend/schemas/ - Pydantic request/response models
• backend/db/models.py - SQLAlchemy ORM models

Service Structure Pattern

from pydantic import BaseModel, Field
from fastapi import APIRouter, HTTPException, Depends, status
from sqlalchemy.orm import Session
from db.database import get_db

router = APIRouter()

@router.post("/endpoint", response_model=ResponseSchema, status_code=status.HTTP_200_OK)
async def my_endpoint(
    request: Request,  # Must be named 'request' for rate limiter
    body: RequestSchema,
    db: Session = Depends(get_db)
):
    # Implementation
    return result

Key Services

Best Practices

1. Use async/await for all I/O operations
2. Validate input with Pydantic schemas with Field constraints
3. Use specific HTTPException status codes
4. Load config from config.yaml (not hardcoded)
5. Rate limiter requires parameter named exactly request
6. Use body for request body schemas (not request)