login_required decorator in Django - Step-by-Step Execution

Concept Flow - login_required decorator

User sends request to view

↓

login_required checks if user is authenticated

↓

Allow access

↓

View executes

The login_required decorator checks if the user is logged in before allowing access to a view. If not logged in, it redirects to the login page.

Execution Sample

Django

@login_required
def dashboard(request):
    return HttpResponse('Welcome to your dashboard')

This code protects the dashboard view so only logged-in users can see it.

Execution Table

Step	Action	User Authenticated?	Result	Next Step
1	User sends request to dashboard view	Unknown	Check authentication	login_required decorator runs
2	login_required checks user authentication	Yes	Allow access	dashboard view executes
3	dashboard view returns response	Yes	HttpResponse with welcome message	Response sent to user
4	User sends request to dashboard view	Unknown	Check authentication	login_required decorator runs
5	login_required checks user authentication	No	Redirect to login page	Redirect response sent to user

💡 Execution stops after sending HttpResponse or redirecting to login page

Variable Tracker

Variable	Start	After Step 2	After Step 3 or 5
user.is_authenticated	Unknown	True or False	True or False
response	None	None	HttpResponse or HttpResponseRedirect

Key Moments - 2 Insights

Why does the user get redirected instead of seeing the dashboard?

Because login_required found user.is_authenticated is False at step 5, so it sends a redirect to the login page instead of running the view.

What happens if the user is authenticated?

At step 2, login_required sees user.is_authenticated is True, so it lets the dashboard view run and return the welcome message (step 3).

Visual Quiz - 3 Questions

Look at the execution table, what happens at step 5?

A Dashboard view returns welcome message

B Authentication is checked again

C User is redirected to login page

D User is logged out

💡 Hint

See row with Step 5 in execution_table where user is not authenticated

At which step does the dashboard view actually run?

A Step 2

B Step 3

C Step 1

D Step 5

💡 Hint

Look at execution_table row where dashboard view returns response

If the user is authenticated, what will the response variable hold after step 3?

A HttpResponse with welcome message

B None

C Redirect to login page

D Error message

💡 Hint

Check variable_tracker for response after step 3

Concept Snapshot

login_required decorator syntax:
@login_required
def view(request):
  # code

Behavior:
- Checks if user is logged in
- If yes, runs view
- If no, redirects to login page

Use to protect views needing login

Full Transcript

The login_required decorator in Django protects views by checking if the user is logged in. When a user requests a protected view, login_required first checks user.is_authenticated. If True, the view runs and returns its response. If False, the user is redirected to the login page. This ensures only logged-in users can access certain pages. The execution table shows these steps clearly: request arrives, authentication checked, then either view runs or redirect happens. Variables like user.is_authenticated and response change accordingly during execution.