Exception middleware in Django - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when an exception is raised in Django middleware?

Consider a Django middleware that catches exceptions during request processing. What is the typical behavior when an exception is raised inside the __call__ method of middleware?

Django

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

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

    def handle_exception(self, request, exception):
        return HttpResponse('Error handled', status=500)

A The middleware ignores the exception and lets it propagate to the next middleware or view.

B The middleware catches the exception and returns a custom error response without crashing the server.

C The middleware logs the exception but still returns the original response from the view.

D The middleware crashes the server immediately without returning any response.

💡 Hint

Think about how exception handling works in Python and how middleware can intercept errors.

When an exception is raised inside the __call__ method, the middleware can catch it and return a custom response, preventing the server from crashing.

📝 Syntax

intermediate

Identify the syntax error in this Django exception middleware snippet

Which option contains a syntax error that will prevent this middleware from running?

Django

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

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

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

A Missing parentheses in HttpResponse call.

B Incorrect indentation of the except block.

C Missing self parameter in handle_exception method.

D Missing colon after try statement.

💡 Hint

Check the syntax of the try-except block carefully.

The try statement must end with a colon. Missing it causes a SyntaxError.

🔧 Debug

advanced

Why does this exception middleware fail to catch exceptions?

Given the following middleware, why does it fail to catch exceptions raised in views?

Django

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

    def process_exception(self, request, exception):
        return HttpResponse('Exception caught', status=500)

    def __call__(self, request):
        response = self.get_response(request)
        return response

A Because <code>process_exception</code> is never called unless middleware is old-style and registered properly.

B Because <code>__call__</code> method does not have a try-except block to catch exceptions.

C Because the middleware does not import HttpResponse.

D Because the middleware returns the response before calling <code>process_exception</code>.

💡 Hint

Think about how Django calls process_exception and middleware styles.

In new-style middleware, process_exception is not called automatically. Exceptions must be caught in __call__.

❓ state_output

advanced

What is the response status code after exception handling in this middleware?

What status code will the client receive when an exception is raised in the view and handled by this middleware?

Django

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

    def __call__(self, request):
        try:
            response = self.get_response(request)
        except Exception:
            return HttpResponse('Handled error', status=418)
        return response

A 200

B 500

C 418

D 404

💡 Hint

Look at the status code set in the HttpResponse returned on exception.

The middleware returns a response with status 418 when an exception occurs.

🧠 Conceptual

expert

Which middleware order ensures exception middleware catches errors from all views and other middleware?

In Django, middleware order matters. Where should exception middleware be placed in the MIDDLEWARE list to catch exceptions from all views and other middleware?

A At the very beginning (first in the list).

B At the very end (last in the list).

C In the middle, after authentication middleware.

D Anywhere, order does not affect exception catching.

💡 Hint

Think about how Django processes middleware in order and how exceptions propagate.

Django processes middleware top-down on request (first to last) and bottom-up on response (last to first). Placing exception middleware first ensures it wraps all others and can catch exceptions from them.