Web Framework: FastAPI#

FastAPI is a modern Python web framework for building APIs with automatic interactive documentation. It’s fast, easy to use, and designed for building production-ready REST APIs.

Here’s a minimal FastAPI app, app.py:

# /// script
# requires-python = ">=3.11"
# dependencies = [
#   "fastapi",
#   "uvicorn",
# ]
# ///

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def root():
    return {"message": "Hello!"}


if __name__ == "__main__":
    import uvicorn

    uvicorn.run(app, host="0.0.0.0", port=8000)

Run this with uv run app.py.

1. Handle errors by raising HTTPException

   from fastapi import HTTPException
   
   
   async def get_item(item_id: int):
       if not valid_item(item_id):
           raise HTTPException(status_code=404, detail=f"Item {item_id} not found")

2. Use middleware for logging

   from fastapi import Request
   import time
   
   
   @app.middleware("http")
   async def add_timing(request: Request, call_next):
       start = time.time()
       response = await call_next(request)
       response.headers["X-Process-Time"] = str(time.time() - start)
       return response

Tools:

• FastAPI CLI: Project scaffolding
• Pydantic: Data validation
• SQLModel: SQL databases
• FastAPI Users: Authentication

Watch this FastAPI Course for Beginners (64 min):