A FastAPI middleware to prettify exceptions using PrettyErrors.
Install the package via pip:
pip install fastapi-pretty-errors
Or, if you’re using Poetry:
poetry add fastapi-pretty-errors
Add the middleware to your FastAPI application:
from fastapi import FastAPI
from fastapi_pretty_errors import PrettyErrorsMiddleware
app = FastAPI()
app.add_middleware(PrettyErrorsMiddleware)You can specify custom configuration options for PrettyErrors when adding the middleware. Any keyword arguments passed to PrettyErrorsMiddleware will be forwarded to pretty_errors.configure() .
from fastapi import FastAPI
from fastapi_pretty_errors import PrettyErrorsMiddleware
app = FastAPI()
app.add_middleware(
PrettyErrorsMiddleware,
# PrettyErrors configuration options
line_number_first=True,
lines_before=5,
lines_after=2,
# ...
)For a full list of configuration options, refer to the PrettyErrors documentation.
Here’s a step-by-step example demonstrating how to use fastapi-pretty-errors in a FastAPI application.
Create a file named main.py with the following content:
from fastapi import FastAPI
from fastapi_pretty_errors import PrettyErrorsMiddleware
import pretty_errors
app = FastAPI()
app.add_middleware(
PrettyErrorsMiddleware,
line_number_first=True,
lines_before=5,
lines_after=2,
line_color=pretty_errors.RED + "> " + pretty_errors.default_config.line_color,
code_color=" " + pretty_errors.default_config.line_color,
truncate_code=True,
display_locals=True,
)
@app.get("/")
async def root():
raise ValueError("An error occurred")Start the FastAPI application:
fastapi run
Send a GET request to the / endpoint. The route raises an exception, so fastapi-pretty-errors returns a generic 500 error message to the client:
curl http://localhost:8000
{"detail":"Unexpected error occured."}
Check the terminal where the FastAPI application is running. You should see a formatted traceback provided by fastapi-pretty-errors :
