Remember me functionality in Flask - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a cookie named 'remember_token' with the user's token.

Flask

response.set_cookie('remember_token', [1])

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

Auser_token

Bsession_id

Ccsrf_token

Drequest_token

Attempts:

3 left

💡 Hint

Common Mistakes

Using session_id or csrf_token instead of the user's token.

The cookie should store the user's unique token to remember them.

2fill in blank

medium

Complete the code to check if the 'remember_token' cookie exists in the request.

Flask

if [1] in request.cookies:

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

A'remember_token'

Bsession

Cuser_token

D'csrf_token'

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for 'session' or 'csrf_token' instead of 'remember_token'.

We check if the cookie named 'remember_token' is present in the request cookies.

3fill in blank

hard

Fix the error in this code that tries to set a cookie with expiration for 'remember me' functionality.

Flask

response.set_cookie('remember_token', token, max_age=[1])

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

A3600

B60*60*24*30

CNone

D60

Attempts:

3 left

💡 Hint

Common Mistakes

Using 3600 (1 hour) or 60 (1 minute) which is too short.

The cookie should last about 30 days, so max_age should be 60*60*24*30 seconds.

4fill in blank

hard

Fill both blanks to retrieve the token from the cookie and verify the user.

Flask

token = request.cookies.get([1])
user = User.query.filter_by([2]=token).first()

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

A'remember_token'

B'session_id'

Cremember_token

Dtoken

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'session_id' or 'remember_token' variable incorrectly.

We get the 'remember_token' cookie and use the variable 'token' to query the user.

5fill in blank

hard

Fill all three blanks to set a secure, HTTP-only cookie with a 7-day expiration.

Flask

response.set_cookie([1], [2], max_age=[3], secure=True, httponly=True)

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

A'remember_token'

Buser_token

C60*60*24*7

D'session_token'

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong cookie names or wrong max_age values.

The cookie name is 'remember_token', the value is the user's token, and max_age is 7 days in seconds.

Practice

1. What does the remember=True parameter do when used with login_user() in Flask-Login?

easy

A. Logs the user out immediately after login.

B. Deletes the user's account after login.

C. Prevents the user from logging in.

D. Keeps the user logged in across browser sessions using cookies.

Solution

1. Step 1: Understand the purpose of remember=True

   This parameter tells Flask-Login to store a cookie that keeps the user logged in even after closing the browser.

2. Step 2: Compare with other options

   Options A, C, and D describe actions that do not relate to keeping the user logged in across sessions.

3. Final Answer:

   Keeps the user logged in across browser sessions using cookies. -> Option D

4. Quick Check:

   Remember me = persistent login [OK]

Hint: Remember me means stay logged in after closing browser [OK]

Common Mistakes:

• Thinking remember=True logs out user
• Confusing remember with user registration
• Assuming remember deletes user data

2. Which of the following is the correct way to enable 'remember me' when logging in a user in Flask?

easy

A. login_user(user, remember=1)

B. login_user(user, remember='yes')

C. login_user(user, remember=True)

D. login_user(user, remember='false')

Solution

1. Step 1: Check the correct parameter type

   The remember parameter expects a boolean value, so True is correct.

2. Step 2: Analyze other options

   Options A, B, and D use integer or string instead of boolean, which is incorrect. login_user(user, remember='false') uses string 'false' which is not boolean False.

3. Final Answer:

   login_user(user, remember=True) -> Option C

4. Quick Check:

   Boolean True enables remember me [OK]

Hint: Use boolean True for remember parameter [OK]

Common Mistakes:

• Passing strings instead of boolean
• Using numbers instead of boolean
• Using 'false' string instead of False

3. Given this Flask code snippet:

from flask_login import login_user

user = get_user()
login_user(user, remember=True)

What will happen if the user closes and reopens the browser?

medium

A. The user will remain logged in automatically.

B. The user will be logged out immediately.

C. The user will see an error message.

D. The user must log in again manually.

Solution

1. Step 1: Understand the effect of remember=True

   This stores a cookie that keeps the user logged in even after browser restart.

2. Step 2: Predict user state after reopening browser

   Because of the cookie, the user session persists, so the user stays logged in automatically.

3. Final Answer:

   The user will remain logged in automatically. -> Option A

4. Quick Check:

   Remember me keeps session after browser close [OK]

Hint: Remember me means no login needed after browser restart [OK]

Common Mistakes:

• Assuming user is logged out after closing browser
• Expecting error on reopening browser
• Confusing remember with session timeout

4. What is wrong with this Flask code snippet for 'remember me' functionality?

login_user(user, remember='True')

medium

A. The user variable is not defined.

B. The remember parameter should be a boolean, not a string.

C. login_user does not accept a remember parameter.

D. The code is correct and will work as expected.

Solution

1. Step 1: Check parameter type for remember

   The remember parameter must be a boolean value, not a string.

2. Step 2: Validate other options

   User variable is assumed defined; login_user accepts remember; so only parameter type is wrong.

3. Final Answer:

   The remember parameter should be a boolean, not a string. -> Option B

4. Quick Check:

   remember must be True/False boolean [OK]

Hint: Use True without quotes for remember [OK]

Common Mistakes:

• Passing 'True' as string instead of boolean
• Forgetting to define user variable
• Assuming remember is unsupported

5. You want to implement a logout button that clears the 'remember me' session in Flask. Which code snippet correctly logs out the user and clears the remembered login?

hard

A. from flask_login import logout_user

logout_user()

B. from flask_login import logout_user

logout_user(remember=False)

C. from flask_login import logout_user

logout_user(user)

D. from flask_login import logout_user

logout_user(clear=True)

Solution

1. Step 1: Understand logout_user behavior

   Calling logout_user() clears the user session and any remember me cookies automatically.

2. Step 2: Analyze other options

   logout_user does not take parameters like remember, user, or clear; these cause errors or are ignored.

3. Final Answer:

   from flask_login import logout_user logout_user() -> Option A

4. Quick Check:

   logout_user() clears session and remember me [OK]

Hint: Use logout_user() without parameters to clear remember me [OK]

Common Mistakes:

• Passing parameters to logout_user()
• Not calling logout_user to clear remember me
• Assuming remember must be cleared separately