asw/archive/packs/flask

ASW Flask/FastAPI Error Pack

Drop-in styled error responses for Flask and FastAPI applications.

Usage

# Copy asw_errors.py to your project directory, then:

from flask import Flask
from asw_errors import register_asw_errors

app = Flask(__name__)
register_asw_errors(app)

from fastapi import FastAPI
from asw_errors import register_asw_errors

app = FastAPI()
register_asw_errors(app)

What you get

ASW-styled HTML error pages for all HTTP error codes:

Code	Status
400	Bad Request
401	Unauthorized
403	Forbidden
404	Not Found
405	Method Not Allowed
408	Request Timeout
409	Conflict
410	Gone
415	Unsupported Media Type
422	Unprocessable Entity
429	Too Many Requests
500	Internal Server Error
502	Bad Gateway
503	Service Unavailable
504	Gateway Timeout

For FastAPI, RequestValidationError (422) is also caught separately.

Linking asw.css

By default, styles are inlined — no external dependencies needed. If your app already serves asw.css, link it instead:

register_asw_errors(app, css_url="/static/asw.css")

The pages will then use your full theme including custom fonts.

Custom app name

The nav bar shows your app's name. Override it:

register_asw_errors(app, app_name="My Service")

Flask auto-detects from app.name; FastAPI from app.title. Both fall back to sensible defaults.

Standalone HTML generation

The error_html() function is also exported if you need to generate pages directly:

from asw_errors import error_html

html = error_html(404, path="/missing/route")
html = error_html(500, css_url="/static/asw.css", app_name="My API")

No dependencies at module level

Flask and FastAPI are imported lazily inside register_asw_errors() — so this file can live in a project that uses either framework without both installed.