Flask session object - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the session object from Flask.

Flask

from flask import [1]

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

Arender_template

Bredirect

Crequest

Dsession

Attempts:

3 left

💡 Hint

Common Mistakes

Importing request instead of session

Using render_template instead of session

Forgetting to import session

The session object is imported from Flask to manage user sessions.

2fill in blank

medium

Complete the code to set a value in the Flask session.

Flask

session[[1]] = 'user123'

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

Ausername

B'username'

C'user_id'

Duser

Attempts:

3 left

💡 Hint

Common Mistakes

Using variable names without quotes as keys

Using keys like user without quotes

Forgetting quotes causes errors

Session keys must be strings, so use quotes around the key name.

3fill in blank

hard

Fix the error in the code to retrieve a session value safely.

Flask

user = session.get([1], None)

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

Ausername

B'user'

C'username'

Duser

Attempts:

3 left

💡 Hint

Common Mistakes

Using unquoted keys causing KeyError

Using wrong key names

Not providing a default value

The key must be a string in quotes to access the session dictionary correctly.

4fill in blank

hard

Fill both blanks to check if a user is logged in using the session.

Flask

if [1] in session and session[[2]] == 'admin':
    print('Admin user')

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

A'username'

B'user'

C'admin'

D'role'

Attempts:

3 left

💡 Hint

Common Mistakes

Using different keys in the condition

Forgetting quotes around keys

Checking wrong keys like 'username'

Check if the key 'user' exists in session and compare the 'role' value to 'admin'.

5fill in blank

hard

Fill all three blanks to clear the session and redirect to home page.

Flask

session.[1]()
return [2](url_for([3]))

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

Aclear

Bredirect

C'home'

Durl_for

Attempts:

3 left

💡 Hint

Common Mistakes

Using session.pop instead of clear for all keys

Forgetting to import redirect or url_for

Passing url_for as string instead of calling it

Use session.clear() to remove all session data, then redirect to the 'home' route.

Practice

1. What is the main purpose of the Flask session object?

easy

A. To store user-specific data temporarily between requests

B. To connect to a database

C. To handle file uploads

D. To render HTML templates

Solution

1. Step 1: Understand the role of session in Flask

   The session object is designed to keep data for a user during their visit, like a temporary storage.

2. Step 2: Compare with other options

   Connecting to databases, handling uploads, and rendering templates are done by other Flask features, not session.

3. Final Answer:

   To store user-specific data temporarily between requests -> Option A

4. Quick Check:

   Session stores user data temporarily [OK]

Hint: Session stores data per user visit like a temporary box [OK]

Common Mistakes:

• Thinking session connects to databases
• Confusing session with template rendering
• Assuming session handles file uploads

2. Which of the following is the correct way to import and use the Flask session object?

easy

A. import flask.session

flask.session['user'] = 'Alice'

B. from flask_session import Session

Session['user'] = 'Alice'

C. from flask import session

session['user'] = 'Alice'

D. import session

session['user'] = 'Alice'

Solution

1. Step 1: Check the correct import statement

   The Flask session object is imported directly from flask using from flask import session.

2. Step 2: Verify usage syntax

   After import, you can use it like a dictionary: session['user'] = 'Alice'.

3. Final Answer:

   from flask import session\nsession['user'] = 'Alice' -> Option C

4. Quick Check:

   Import session from flask and assign like dict [OK]

Hint: Import session directly from flask, then use like a dict [OK]

Common Mistakes:

• Trying to import session from flask_session package
• Using wrong import syntax like import session
• Accessing session as flask.session instead of from flask import session

3. What will be the output of this Flask route code snippet?

from flask import Flask, session
app = Flask(__name__)
app.secret_key = 'secret'

@app.route('/')
def index():
    session['count'] = session.get('count', 0) + 1
    return f"Count: {session['count']}"

medium

A. Count: 1

B. Error: session not defined

C. Count: 2

D. Count: 0

Solution

1. Step 1: Understand session initialization and increment

   The code gets 'count' from session or 0 if not set, then adds 1 and stores it back.

2. Step 2: Determine output on first request

   On first visit, 'count' is not in session, so session.get('count', 0) returns 0, then incremented to 1.

3. Final Answer:

   Count: 1 -> Option A

4. Quick Check:

   First visit count starts at 1 [OK]

Hint: First session count starts at 1 after increment [OK]

Common Mistakes:

• Assuming count starts at 0 output
• Expecting count to be 2 on first visit
• Forgetting to set secret_key causing errors

4. Identify the error in this Flask code using session:

from flask import Flask, session
app = Flask(__name__)

@app.route('/')
def index():
    session['user'] = 'Bob'
    return f"User: {session['user']}"

medium

A. Missing import of session

B. Missing app.secret_key causing session error

C. Incorrect session syntax

D. Route decorator syntax error

Solution

1. Step 1: Check for secret_key setting

   Flask sessions require app.secret_key to encrypt session data securely.

2. Step 2: Identify missing secret_key

   The code does not set app.secret_key, so session will raise an error or not work properly.

3. Final Answer:

   Missing app.secret_key causing session error -> Option B

4. Quick Check:

   Secret key missing breaks session [OK]

Hint: Always set app.secret_key before using session [OK]

Common Mistakes:

• Forgetting to set secret_key
• Assuming session works without secret_key
• Misreading import or decorator syntax

5. You want to store a user's preferred language in the Flask session and ensure it persists across requests. Which code snippet correctly sets and retrieves this value safely?

hard

A. session['lang'] = 'en'
lang = session['language']

B. session['lang'] = 'en'
lang = session['lang']

C. session.set('lang', 'en')
lang = session.get('lang')

D. session['lang'] = 'en'
lang = session.get('lang', 'default')

Solution

1. Step 1: Set session value correctly

   Assigning with session['lang'] = 'en' is correct to store the language.

2. Step 2: Retrieve session value safely

   Using session.get('lang', 'default') safely gets the value or returns 'default' if missing, avoiding errors.

3. Final Answer:

   session['lang'] = 'en'\nlang = session.get('lang', 'default') -> Option D

4. Quick Check:

   Use session.get() to avoid KeyError [OK]

Hint: Use session.get() to safely read session keys [OK]

Common Mistakes:

• Using session.set() which does not exist
• Accessing wrong key causing KeyError
• Not providing default value when reading session