Why middleware matters in Django - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a middleware class to the Django settings.

Django

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    [1],
    'django.middleware.common.CommonMiddleware',
]

Drag options to blanks, or click blank then click option'

A'django.middleware.csrf.CsrfViewMiddleware'

B'django.middleware.session.SessionMiddleware'

C'django.middleware.clickjacking.XFrameOptionsMiddleware'

D'django.middleware.locale.LocaleMiddleware'

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing middleware unrelated to sessions.

Forgetting to include middleware that manages security.

The SessionMiddleware manages sessions and is commonly added in the middleware list.

2fill in blank

medium

Complete the middleware method to process a request in a custom middleware class.

Django

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

    def [1](self, request):
        # Code to run before view
        response = self.get_response(request)
        # Code to run after view
        return response

Drag options to blanks, or click blank then click option'

A__call__

Bprocess_request

Cprocess_response

Dprocess_view

Attempts:

3 left

💡 Hint

Common Mistakes

Using old-style middleware methods like process_request.

Not defining the __call__ method in new middleware.

The __call__ method is used in Django middleware classes to process requests and responses.

3fill in blank

hard

Fix the error in the middleware to correctly modify the response headers.

Django

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

    def __call__(self, request):
        response = self.get_response(request)
        response.[1]['X-Custom-Header'] = 'Value'
        return response

Drag options to blanks, or click blank then click option'

Aadd_header

B__setitem__

Cheaders

DMETA

Attempts:

3 left

💡 Hint

Common Mistakes

Using META which is for request headers, not response.

Trying to call a method instead of accessing the headers attribute.

The headers attribute is used to access and modify HTTP headers in Django HttpResponse objects.

4fill in blank

hard

Fill both blanks to create a middleware that blocks requests from a specific IP address.

Django

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

    def __call__(self, request):
        if request.META.get('[1]') == '[2]':
            from django.http import HttpResponseForbidden
            return HttpResponseForbidden('Forbidden')
        return self.get_response(request)

Drag options to blanks, or click blank then click option'

AREMOTE_ADDR

BHTTP_USER_AGENT

C192.168.1.1

D127.0.0.1

Attempts:

3 left

💡 Hint

Common Mistakes

Using HTTP_USER_AGENT instead of REMOTE_ADDR.

Blocking an IP address that is not the one intended.

The REMOTE_ADDR key in request.META holds the client's IP address. Blocking 127.0.0.1 denies localhost requests.

5fill in blank

hard

Fill all three blanks to write a middleware that adds a custom header only for authenticated users.

Django

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

    def __call__(self, request):
        response = self.get_response(request)
        if request.[1].[2]:
            response.[3]['X-User-Status'] = 'Authenticated'
        return response

Drag options to blanks, or click blank then click option'

Auser

Bis_authenticated

Cheaders

Dsession

Attempts:

3 left

💡 Hint

Common Mistakes

Using request.session instead of request.user.

Trying to set headers directly without using the headers attribute.

Access request.user.is_authenticated to check if the user is logged in, then add the header via response.headers.

Practice

1. What is the main purpose of middleware in a Django application?

easy

A. To process requests and responses globally before reaching views

B. To define database models and relationships

C. To create HTML templates for rendering pages

D. To handle user authentication only

Solution

1. Step 1: Understand middleware role

   Middleware acts on requests and responses before and after views run.

2. Step 2: Compare options to middleware function

   Only To process requests and responses globally before reaching views describes processing requests and responses globally, which matches middleware's purpose.

3. Final Answer:

   To process requests and responses globally before reaching views -> Option A

4. Quick Check:

   Middleware = global request/response processing [OK]

Hint: Middleware acts on requests/responses before views [OK]

Common Mistakes:

• Confusing middleware with models or templates
• Thinking middleware only handles authentication
• Assuming middleware runs after views only

2. Which of the following is the correct way to add a custom middleware class in Django's settings?

easy

A. Add 'myapp.middleware.MyMiddleware' to TEMPLATES list

B. Add 'myapp.middleware.MyMiddleware' to MIDDLEWARE list in settings.py

C. Add 'myapp.middleware.MyMiddleware' to INSTALLED_APPS list

D. Add 'myapp.middleware.MyMiddleware' to DATABASES dictionary

Solution

1. Step 1: Identify where middleware is configured

   Django uses the MIDDLEWARE list in settings.py to register middleware classes.

2. Step 2: Match the correct setting for middleware

   Only Add 'myapp.middleware.MyMiddleware' to MIDDLEWARE list in settings.py correctly adds the middleware class path to the MIDDLEWARE list.

3. Final Answer:

   Add 'myapp.middleware.MyMiddleware' to MIDDLEWARE list in settings.py -> Option B

4. Quick Check:

   Middleware goes in MIDDLEWARE list [OK]

Hint: Middleware classes go in MIDDLEWARE list, not INSTALLED_APPS [OK]

Common Mistakes:

• Adding middleware to INSTALLED_APPS instead of MIDDLEWARE
• Placing middleware in TEMPLATES or DATABASES settings
• Using incorrect string format for middleware path

3. Given this middleware code snippet, what will be printed when a request is processed?

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

    def __call__(self, request):
        print('Before view')
        response = self.get_response(request)
        print('After view')
        return response

medium

A. Before view printed before the view runs, After view printed after

B. Only Before view is printed

C. Only After view is printed

D. No output is printed

Solution

1. Step 1: Analyze __call__ method flow

   The middleware prints 'Before view', calls the view via get_response, then prints 'After view'.

2. Step 2: Understand order of prints

   'Before view' prints before the view runs, 'After view' prints after the view returns.

3. Final Answer:

   Before view printed before the view runs, After view printed after -> Option A

4. Quick Check:

   Middleware prints before and after view [OK]

Hint: Middleware __call__ runs code before and after get_response [OK]

Common Mistakes:

• Thinking only one print runs
• Confusing order of prints
• Assuming middleware skips printing

4. You wrote this middleware but it causes an error:

class ErrorMiddleware:
    def __init__(self, get_response):
        pass

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

What is the problem?

medium

A. Middleware classes must inherit from a base class

B. The __call__ method should not return anything

C. The __init__ method does not save get_response, causing AttributeError

D. The __init__ method should not have parameters

Solution

1. Step 1: Check __init__ method implementation

   The __init__ method ignores get_response and does not save it as self.get_response.

2. Step 2: Understand __call__ method usage

   __call__ tries to call self.get_response, but it does not exist, causing an AttributeError.

3. Final Answer:

   The __init__ method does not save get_response, causing AttributeError -> Option C

4. Quick Check:

   Save get_response in __init__ to avoid errors [OK]

Hint: Always save get_response in __init__ as self.get_response [OK]

Common Mistakes:

• Not storing get_response in __init__
• Assuming __call__ doesn't need to return response
• Thinking middleware must inherit from a base class

5. You want to create middleware that adds a custom header X-App-Version with value 1.0 to every response. Which code snippet correctly implements this?

hard

A. class VersionMiddleware:
def __init__(self, get_response):
self.get_response = get_response
def process_response(self, request, response):
response['X-App-Version'] = '1.0'
return response

B. class VersionMiddleware:
def __init__(self, get_response):
self.get_response = get_response
def process_request(self, request):
request['X-App-Version'] = '1.0'

C. class VersionMiddleware:
def __init__(self, get_response):
self.get_response = get_response
def __call__(self, request):
request['X-App-Version'] = '1.0'
return self.get_response(request)

D. class VersionMiddleware:
def __init__(self, get_response):
self.get_response = get_response
def __call__(self, request):
response = self.get_response(request)
response['X-App-Version'] = '1.0'
return response

Solution

1. Step 1: Identify where to add headers in middleware

   Headers must be added to the response object after the view runs, inside __call__.

2. Step 2: Check each option's method

   class VersionMiddleware:
       def __init__(self, get_response):
           self.get_response = get_response
       def __call__(self, request):
           response = self.get_response(request)
           response['X-App-Version'] = '1.0'
           return response

   correctly adds the header after calling get_response and returns the modified response.

3. Final Answer:

   correctly adds the header in __call__ after response creation -> Option D

4. Quick Check:

   Add headers after get_response in __call__ [OK]

Hint: Modify response headers after get_response call in __call__ [OK]

Common Mistakes:

• Trying to add headers to request instead of response
• Using process_request which can't modify response
• Not returning the response object