Session lifetime in Flask - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the session lifetime to 30 minutes in Flask.

Flask

from flask import Flask
from datetime import timedelta
app = Flask(__name__)
app.config['PERMANENT_SESSION_LIFETIME'] = timedelta(minutes=[1])

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

A60

B30

C15

D45

Attempts:

3 left

💡 Hint

Common Mistakes

Using seconds instead of minutes

Forgetting to use timedelta

Setting the wrong number of minutes

The session lifetime is set using timedelta with the number of minutes. Here, 30 minutes is the correct value.

2fill in blank

medium

Complete the code to make the session permanent in a Flask route.

Flask

from flask import session
@app.route('/')
def index():
    session.[1] = True
    return 'Session is permanent'

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

Apermanence

Bmake_permanent

Cset_permanent

Dpermanent

Attempts:

3 left

💡 Hint

Common Mistakes

Using a method instead of a property

Using incorrect property names

Not setting the property to True

To make a session permanent in Flask, set session.permanent = True inside the route.

3fill in blank

hard

Fix the error in setting the session lifetime to 1 hour in Flask.

Flask

app.config['PERMANENT_SESSION_LIFETIME'] = [1](hours=1)

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

Atime

Bdatetime

Ctimedelta

Dduration

Attempts:

3 left

💡 Hint

Common Mistakes

Using datetime instead of timedelta

Using undefined classes like time or duration

Not importing timedelta

The correct class to set session lifetime is timedelta from datetime module.

4fill in blank

hard

Fill both blanks to set a secret key and session lifetime to 15 minutes in Flask.

Flask

app = Flask(__name__)
app.config['[1]'] = 'mysecretkey'
app.config['[2]'] = timedelta(minutes=15)

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

ASECRET_KEY

BSESSION_KEY

CPERMANENT_SESSION_LIFETIME

DSESSION_LIFETIME

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong config keys like SESSION_KEY or SESSION_LIFETIME

Mixing up the order of config keys

Not setting SECRET_KEY

The secret key is set with 'SECRET_KEY' and session lifetime with 'PERMANENT_SESSION_LIFETIME'.

5fill in blank

hard

Fill all three blanks to create a Flask app, set a secret key, and make the session permanent with a 10-minute lifetime.

Flask

from flask import Flask, session
from datetime import [1]
app = Flask(__name__)
app.config['[2]'] = 'secret123'
app.config['PERMANENT_SESSION_LIFETIME'] = timedelta(minutes=10)
@app.route('/')
def home():
    session.[3] = True
    return 'Session set to permanent'

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

Atimedelta

BSECRET_KEY

Cpermanent

Ddatetime

Attempts:

3 left

💡 Hint

Common Mistakes

Importing datetime instead of timedelta

Using wrong config key for secret

Not setting session.permanent to True

Import timedelta, set SECRET_KEY, and mark session.permanent = True to make session permanent.

Practice

1. What does setting session.permanent = True in a Flask app do?

easy

A. It makes the session use the permanent_session_lifetime duration.

B. It deletes the session immediately after the request ends.

C. It disables session cookies in the browser.

D. It resets the session lifetime to zero.

Solution

1. Step 1: Understand session permanence in Flask

   Setting session.permanent = True tells Flask to keep the session alive for a set duration instead of ending it when the browser closes.

2. Step 2: Connect to permanent_session_lifetime

   The session will then use the time defined in app.permanent_session_lifetime to decide how long it lasts.

3. Final Answer:

   It makes the session use the permanent_session_lifetime duration. -> Option A

4. Quick Check:

   session.permanent = True means use permanent_session_lifetime [OK]

Hint: Permanent session means use app.permanent_session_lifetime [OK]

Common Mistakes:

• Thinking session.permanent deletes session immediately
• Confusing permanent with disabling cookies
• Assuming session resets lifetime to zero

2. Which of the following is the correct way to set a session lifetime of 30 minutes in Flask?

easy

A. app.permanent_session_lifetime = timedelta(minutes=30)

B. session.lifetime = 30

C. app.session_lifetime = 30

D. session.permanent_session_lifetime = 30

Solution

1. Step 1: Identify the correct Flask attribute for session lifetime

   The Flask app uses app.permanent_session_lifetime to set how long permanent sessions last.

2. Step 2: Use the correct data type

   This value must be a timedelta object from Python's datetime module, e.g., timedelta(minutes=30).

3. Final Answer:

   app.permanent_session_lifetime = timedelta(minutes=30) -> Option A

4. Quick Check:

   Use app.permanent_session_lifetime with timedelta [OK]

Hint: Use app.permanent_session_lifetime with timedelta object [OK]

Common Mistakes:

• Setting session.lifetime instead of app.permanent_session_lifetime
• Assigning integer instead of timedelta
• Using session.permanent_session_lifetime which does not exist

3. Given this Flask code snippet, what will be the session lifetime if the user sets session.permanent = True and app.permanent_session_lifetime = timedelta(hours=1)?

from flask import Flask, session
from datetime import timedelta

app = Flask(__name__)
app.secret_key = 'secret'
app.permanent_session_lifetime = timedelta(hours=1)

@app.route('/')
def index():
    session.permanent = True
    session['user'] = 'Alice'
    return 'Session set'

medium

A. The session will expire immediately after the request.

B. The session will last 24 hours by default.

C. The session will last until the browser is closed.

D. The session will last 1 hour before expiring.

Solution

1. Step 1: Check the session permanence setting

   The code sets session.permanent = True, so the session uses the app's permanent lifetime.

2. Step 2: Identify the permanent session lifetime

   The app sets app.permanent_session_lifetime = timedelta(hours=1), so the session lasts 1 hour.

3. Final Answer:

   The session will last 1 hour before expiring. -> Option D

4. Quick Check:

   session.permanent True + app.permanent_session_lifetime = 1 hour [OK]

Hint: Permanent session uses app.permanent_session_lifetime duration [OK]

Common Mistakes:

• Assuming session expires immediately after request
• Thinking session lasts until browser closes when permanent=True
• Assuming default 24 hours without setting

4. You wrote this Flask code but the session never expires even after 1 hour. What is the likely mistake?

from flask import Flask, session
from datetime import timedelta

app = Flask(__name__)
app.secret_key = 'secret'
app.permanent_session_lifetime = timedelta(hours=1)

@app.route('/')
def index():
    session['user'] = 'Bob'
    return 'Session set'

medium

A. The secret key is missing, so sessions don't expire.

B. You need to set app.session_lifetime instead.

C. You forgot to set session.permanent = True.

D. You must call session.save() to apply lifetime.

Solution

1. Step 1: Check if session is marked permanent

   The code sets session['user'] but does not set session.permanent = True.

2. Step 2: Understand session expiration behavior

   Without session.permanent = True, the session lasts only until the browser closes, ignoring permanent_session_lifetime.

3. Final Answer:

   You forgot to set session.permanent = True. -> Option C

4. Quick Check:

   session.permanent must be True to use permanent_session_lifetime [OK]

Hint: Set session.permanent = True to activate lifetime setting [OK]

Common Mistakes:

• Assuming setting session key alone applies lifetime
• Using app.session_lifetime which is invalid
• Thinking secret key affects session expiration
• Calling non-existent session.save() method

5. You want to create a Flask app where sessions last 2 hours, but only if the user chooses 'Remember me'. Otherwise, sessions should expire when the browser closes. Which code snippet correctly implements this?

hard

A. app.permanent_session_lifetime = timedelta(hours=2)

@app.route('/login', methods=['POST'])
def login():
session.permanent = True
session['user'] = request.form['username']
return 'Logged in'

B. app.permanent_session_lifetime = timedelta(hours=2)

@app.route('/login', methods=['POST'])
def login():
if request.form.get('remember') == 'yes':
session.permanent = True
else:
session.permanent = False
session['user'] = request.form['username']
return 'Logged in'

C. app.permanent_session_lifetime = timedelta(hours=2)

@app.route('/login', methods=['POST'])
def login():
session.permanent = False
session['user'] = request.form['username']
return 'Logged in'

D. app.session_lifetime = timedelta(hours=2)

@app.route('/login', methods=['POST'])
def login():
if request.form.get('remember') == 'yes':
session.permanent = True
session['user'] = request.form['username']
return 'Logged in'

Solution

1. Step 1: Set the permanent session lifetime correctly

   Use app.permanent_session_lifetime = timedelta(hours=2) to define 2 hours for permanent sessions.

2. Step 2: Control session permanence based on user choice

   Inside the login route, check if the user selected 'Remember me'. If yes, set session.permanent = True, else set it to False.

3. Step 3: Assign the user to session and return response

   Store the username in session and return a confirmation message.

4. Final Answer:

   app.permanent_session_lifetime = timedelta(hours=2) @app.route('/login', methods=['POST']) def login(): if request.form.get('remember') == 'yes': session.permanent = True else: session.permanent = False session['user'] = request.form['username'] return 'Logged in' -> Option B

5. Quick Check:

   Conditional session.permanent with app.permanent_session_lifetime set [OK]

Hint: Set session.permanent True only if 'Remember me' chosen [OK]

Common Mistakes:

• Not setting session.permanent based on user input
• Using app.session_lifetime instead of app.permanent_session_lifetime
• Always setting session.permanent True ignoring user choice