Exception middleware in Django

Introduction

Exception middleware helps catch errors in your Django app and handle them gracefully. It keeps your app from crashing and shows friendly error messages.

You want to log errors automatically when something goes wrong.

You want to show custom error pages instead of default ones.

You want to send notifications when exceptions happen.

You want to clean up resources or do special actions after an error.

You want to handle specific errors differently in one place.

Syntax

Django

class YourExceptionMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        try:
            response = self.get_response(request)
            return response
        except Exception as e:
            # Handle the exception here
            return self.handle_exception(request, e)

    def handle_exception(self, request, exception):
        # Your custom error handling logic
        pass

The middleware class must accept get_response in __init__.

The __call__ method processes the request and can catch exceptions.

Examples

This middleware catches any exception and returns a simple error message.

Django

from django.http import HttpResponse

class SimpleExceptionMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        try:
            return self.get_response(request)
        except Exception:
            return HttpResponse('Something went wrong!', status=500)

This middleware logs the error before returning a 500 response.

Django

from django.http import HttpResponse
import logging

class LoggingExceptionMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        try:
            return self.get_response(request)
        except Exception as e:
            logging.error(f'Error: {e}')
            return HttpResponse('Internal server error', status=500)

Sample Program

This middleware catches any exception during request processing and returns a 500 response with the error message.

Django

from django.http import HttpResponse

class ExceptionMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        try:
            response = self.get_response(request)
            return response
        except Exception as e:
            return self.handle_exception(request, e)

    def handle_exception(self, request, exception):
        return HttpResponse(f'Error caught: {exception}', status=500)

# Usage in settings.py:
# MIDDLEWARE = [
#     'yourapp.middleware.ExceptionMiddleware',
#     ...
# ]

Important Notes

Always add your middleware class to the MIDDLEWARE list in settings.py.

Be careful not to hide useful error details during development; use custom error pages mainly in production.

You can customize handle_exception to log errors or send alerts.

Summary

Exception middleware catches errors during request handling.

It helps show friendly error messages or log problems.

Write a class with __init__ and __call__ methods to create it.