FastAPI Problems

fastapi_problem is a set of exceptions and handlers for use in fastapi applications to support easy error management and responses.

Each exception easily marshals to JSON based on the RFC9457 spec for use in api errors.

Check the docs for more details.

Custom Errors

Subclassing the convenience classes provide a simple way to consistently raise the same error with detail/extras changing based on the raised context.

from fastapi_problem.error import NotFoundProblem


class UserNotFoundError(NotFoundProblem):
    title = "User not found."

raise UserNotFoundError(detail="detail")

{
    "type": "user-not-found",
    "title": "User not found",
    "detail": "detail",
    "status": 404,
}

Usage

import fastapi
from fastapi_problem.handler import add_exception_handler, new_exception_handler


app = fastapi.FastAPI()
eh = new_exception_handler()
add_exception_handler(app, eh)

@app.get("/user")
async def get_user():
    raise UserNotFoundError("No user found.")

$ curl localhost:8000/user
{

    "type": "user-not-found",
    "title": "User not found",
    "detail": "No user found.",
    "status": 404,
}