login_required decorator in Django - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when an anonymous user accesses a view with @login_required?

Consider a Django view decorated with @login_required. What is the behavior when an anonymous (not logged in) user tries to access this view?

Django

from django.contrib.auth.decorators import login_required
from django.http import HttpResponse

@login_required
def secret_view(request):
    return HttpResponse('Secret content')

A The user sees the 'Secret content' message without logging in.

B The view raises a TypeError because the user is anonymous.

C The user is redirected to the login page defined by LOGIN_URL setting.

D The server returns a 403 Forbidden error.

💡 Hint

Think about what Django does to protect views from anonymous users.

The @login_required decorator checks if the user is authenticated. If not, it redirects them to the login page specified by LOGIN_URL.

📝 Syntax

intermediate

Which code correctly applies @login_required to a class-based view?

You want to protect a Django class-based view using the @login_required decorator. Which option correctly applies it?

Django

from django.contrib.auth.decorators import login_required
from django.utils.decorators import method_decorator
from django.views import View
from django.http import HttpResponse

class MyView(View):
    def get(self, request):
        return HttpResponse('Hello')

A

@method_decorator(login_required, name='dispatch')
class MyView(View):
    def get(self, request):
        return HttpResponse('Hello')

B

@login_required
class MyView(View):
    def get(self, request):
        return HttpResponse('Hello')

C

class MyView(View):
    def get(self, request):
        @login_required
        return HttpResponse('Hello')

D

class MyView(View):
    @login_required
def get(self, request):
        return HttpResponse('Hello')

💡 Hint

Remember that @login_required is a function decorator, and class-based views need a special approach.

For class-based views, you use method_decorator on the dispatch method or with the name argument to apply @login_required properly.

❓ state_output

advanced

What is the value of request.user after @login_required redirects?

In a Django view decorated with @login_required, if the user is not logged in and gets redirected to the login page, what is the value of request.user in the login view?

Django

from django.contrib.auth.decorators import login_required
from django.http import HttpResponse

@login_required
def secret_view(request):
    return HttpResponse(f'User: {request.user}')

A <User: AnonymousUser>

B <User: None>

C Raises AttributeError because user is missing

D <User: admin>

💡 Hint

Think about what Django sets for unauthenticated users.

Django sets request.user to an AnonymousUser instance for users who are not logged in.

🔧 Debug

advanced

Why does @login_required not redirect in this code?

This Django view uses @login_required but anonymous users can still access it. Why?

from django.contrib.auth.decorators import login_required
from django.http import HttpResponse

@login_required
def my_view():
    return HttpResponse('Hello')

A The decorator is applied incorrectly; it should be @login_required() with parentheses.

B The view function is missing the request parameter, so the decorator fails silently.

C LOGIN_URL is not set in settings.py, so redirect does not happen.

D The HttpResponse is returned before the decorator runs.

💡 Hint

Check the function signature carefully.

The view function must accept the request argument. Without it, Django cannot pass the request, so the decorator does not work properly.

🧠 Conceptual

expert

How does @login_required handle the 'next' parameter in redirects?

When @login_required redirects an anonymous user to the login page, it appends a 'next' parameter to the URL. What is the purpose of this 'next' parameter?

A It disables caching on the login page.

B It is used to track how many times the user tried to access protected views.

C It stores the user's session ID for security checks.

D It tells the login view where to redirect the user after successful login.

💡 Hint

Think about user experience after login.

The 'next' parameter holds the original URL the user wanted to visit, so after login, Django can redirect them there.