Session expiry behavior in Django - Step-by-Step Execution

Concept Flow - Session expiry behavior

User logs in

↓

Session created with expiry time

↓

User makes requests

↓

Check if session expired?

No→Continue session

Yes↓

Session expired

↓

User redirected to login

This flow shows how Django creates a session with an expiry time, checks it on each request, and expires it when time runs out.

Execution Sample

Django

from django.contrib.auth import logout

# User logs in
request.session.set_expiry(300)  # 5 minutes expiry

# On each request
if request.session.get_expiry_age() <= 0:
    # Session expired
    logout(request)

This code sets a session expiry of 5 minutes and checks on each request if the session has expired to log out the user.

Execution Table

Step	Action	Session Expiry Time (seconds)	Time Passed (seconds)	Session Valid?	Result
1	User logs in, session created	300	0	Yes	Session active
2	User makes request after 100s	300	100	Yes	Session active
3	User makes request after 299s	300	299	Yes	Session active
4	User makes request after 301s	300	301	No	Session expired, user logged out
5	User tries request after expiry	300	350	No	Redirect to login

💡 Session expires when time passed exceeds expiry time (301 > 300 seconds)

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5
session_expiry_time	None	300	300	300	300	300
time_passed	0	0	100	299	301	350
session_valid	False	True	True	True	False	False

Key Moments - 2 Insights

Why does the session become invalid after 301 seconds but not at 299 seconds?

Because the session expiry time is set to 300 seconds. At 299 seconds, time passed is less than expiry, so session is valid. At 301 seconds, time passed exceeds expiry, so session is invalid (see execution_table rows 3 and 4).

What happens if the user tries to make a request after the session expired?

The session is no longer valid, so Django logs out the user and redirects to login (see execution_table row 5).

Visual Quiz - 3 Questions

Look at the execution table, what is the session_valid value at step 3?

A True

B False

C None

D Error

💡 Hint

Check the 'Session Valid?' column at step 3 in the execution_table.

At which step does the session expire according to the execution table?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look for the first step where 'Session Valid?' is 'No' in the execution_table.

If the session expiry time was set to 600 seconds, how would the session_valid value change at step 4?

A It would be False

B It would be True

C It would be None

D It would cause an error

💡 Hint

Compare the time passed (301s) with the new expiry time (600s) in variable_tracker.

Concept Snapshot

Django sessions store user data with an expiry time.
Set expiry with request.session.set_expiry(seconds).
On each request, check expiry with get_expiry_age().
If expired, session is invalid and user is logged out.
Expired sessions redirect users to login.
This keeps user data secure and session fresh.

Full Transcript

In Django, when a user logs in, a session is created with a set expiry time, for example 300 seconds (5 minutes). Each time the user makes a request, Django checks if the session has expired by comparing the time passed since creation with the expiry time. If the time passed is less than the expiry, the session remains valid and the user continues. If the time passed exceeds the expiry, the session is invalidated, the user is logged out, and redirected to the login page. This process ensures sessions do not last forever and helps keep user data secure.