Session data storage in Flask - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Flask session code?

Consider this Flask route that sets and reads session data. What will be printed when accessing the '/count' URL twice in a row?

Flask

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

@app.route('/count')
def count():
    if 'visits' in session:
        session['visits'] += 1
    else:
        session['visits'] = 1
    return f"Visit count: {session['visits']}"

A KeyError on second visit

B Visit count: 0 on first visit, Visit count: 1 on second visit

C Visit count: 1 on first visit, Visit count: 2 on second visit

D Visit count: 1 on both visits

💡 Hint

Think about how Flask session stores data between requests for the same client.

Flask session stores data in a cookie signed with the secret key. On first visit, 'visits' is set to 1. On second visit, it increments to 2.

📝 Syntax

intermediate

Which option correctly sets a session variable in Flask?

You want to store the username 'alice' in the Flask session. Which code snippet does this correctly?

A session['username'] = 'alice'

B session.username = 'alice'

C session.set('username', 'alice')

D session.add('username', 'alice')

💡 Hint

Flask session behaves like a dictionary.

Flask session is a dictionary-like object. You set values using square brackets and assignment.

🔧 Debug

advanced

Why does this Flask session code raise a RuntimeError?

Examine this Flask code snippet. Why does it raise a RuntimeError: Working outside of request context?

Flask

from flask import session

def set_user():
    session['user'] = 'bob'

set_user()

A Because 'user' is a reserved session key

B Because session can only be accessed inside a request context

C Because session requires a database connection

D Because the secret_key is missing

💡 Hint

When does Flask create the session object?

Flask session is only available during a request. Calling session outside a request context causes RuntimeError.

❓ state_output

advanced

What is the session content after this sequence of requests?

Given this Flask route, what will be the session content after visiting '/add/5' then '/add/3'?

Flask

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

@app.route('/add/<int:num>')
def add(num):
    total = session.get('total', 0)
    total += num
    session['total'] = total
    return f"Total: {total}"

A {}

B {'total': 3}

C {'total': 5}

D {'total': 8}

💡 Hint

Session data persists and accumulates across requests from the same client.

First request sets total to 5, second adds 3 making total 8 in session.

🧠 Conceptual

expert

Which statement about Flask session storage is true?

Select the correct statement about how Flask session stores data by default.

A Flask session stores data on the client inside a signed cookie

B Flask session stores data on the server in a database by default

C Flask session data is encrypted and stored in server memory

D Flask session requires Redis to store session data

💡 Hint

Think about where Flask keeps session data without extra setup.

By default, Flask stores session data client-side in a cookie signed with the secret key to prevent tampering.