Role-based access control in Flask - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the Flask-Login extension needed for user session management.

Flask

from flask_login import [1]

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

ALoginManager

BUserMixin

Ccurrent_user

Dlogin_required

Attempts:

3 left

💡 Hint

Common Mistakes

Importing UserMixin instead of LoginManager

Using login_required decorator here

The LoginManager class is imported to manage user sessions and handle login-related tasks in Flask.

2fill in blank

medium

Complete the code to protect a Flask route so only logged-in users can access it.

Flask

@app.route('/dashboard')
@[1]
def dashboard():
    return 'Welcome to your dashboard!'

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

Acurrent_user

Blogin_manager

Cuser_loader

Dlogin_required

Attempts:

3 left

💡 Hint

Common Mistakes

Using login_manager as decorator

Using current_user as decorator

The @login_required decorator restricts access to the route to only logged-in users.

3fill in blank

hard

Fix the error in the user loader function to load a user by ID.

Flask

@login_manager.user_loader
def load_user([1]):
    return User.query.get(int(user_id))

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

Aid

Buser

Cuser_id

Duid

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'user' or 'id' instead of 'user_id' as parameter name

The parameter must be named user_id to match the variable used inside the function.

4fill in blank

hard

Fill both blanks to check if the current user has the 'admin' role and restrict access accordingly.

Flask

from flask_login import current_user
from flask import abort

@app.route('/admin')
def admin_panel():
    if current_user.[1]('admin'):
        return 'Welcome Admin'
    else:
        return [2]('Access denied', 403)

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

Ahas_role

Babort

Credirect

Dlogin_required

Attempts:

3 left

💡 Hint

Common Mistakes

Using redirect instead of abort for access denial

Using login_required inside the function incorrectly

The has_role method checks if the user has the 'admin' role. abort(403) sends a forbidden error if not authorized.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps usernames to their roles only if the user is active.

Flask

user_roles = {user.[1]: user.[2] for user in users if user.[3]

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

Ausername

Brole

Cis_active

Demail

Attempts:

3 left

💡 Hint

Common Mistakes

Using email instead of username

Checking wrong attribute for active status

This comprehension creates a dictionary with usernames as keys and roles as values, but only for users who are active.

Practice

1. What is the main purpose of role-based access control (RBAC) in a Flask application?

easy

A. To automatically generate user interfaces

B. To speed up the Flask server response time

C. To restrict user actions based on their assigned roles

D. To store user passwords securely

Solution

1. Step 1: Understand RBAC concept

   RBAC means users can only do things allowed by their roles, like admin or user.

2. Step 2: Identify RBAC purpose in Flask

   In Flask, RBAC limits access to routes or actions based on roles.

3. Final Answer:

   To restrict user actions based on their assigned roles -> Option C

4. Quick Check:

   RBAC = restrict actions by role [OK]

Hint: RBAC controls what users can do by their role [OK]

Common Mistakes:

• Confusing RBAC with performance optimization
• Thinking RBAC manages UI generation
• Mixing RBAC with password security

2. Which Flask decorator is commonly used to protect a route so only logged-in users with a specific role can access it?

easy

A. @csrf_protect

B. @login_required

C. @app.route

D. @role_required('admin')

Solution

1. Step 1: Identify decorators for access control

   @login_required ensures user is logged in but does not check role.

2. Step 2: Find decorator checking specific role

   @role_required('admin') restricts access to users with 'admin' role.

3. Final Answer:

   @role_required('admin') -> Option D

4. Quick Check:

   Role check decorator = @role_required [OK]

Hint: Use @role_required to check user roles on routes [OK]

Common Mistakes:

• Using @login_required alone for role checks
• Confusing @app.route with access control
• Mistaking @csrf_protect for role restriction

3. Given this Flask route code snippet:

@app.route('/dashboard')
@role_required('editor')
def dashboard():
    return 'Welcome Editor'

What happens if a logged-in user with role 'viewer' tries to access '/dashboard'?

medium

A. They get redirected or denied access

B. They can access but with limited features

C. They get a server error

D. They see 'Welcome Editor' message

Solution

1. Step 1: Understand role_required decorator effect

   @role_required('editor') allows only users with 'editor' role to access the route.

2. Step 2: Check user role 'viewer' against required 'editor'

   User role 'viewer' does not match 'editor', so access is denied or redirected.

3. Final Answer:

   They get redirected or denied access -> Option A

4. Quick Check:

   Role mismatch = access denied [OK]

Hint: Role mismatch blocks access, not error or partial view [OK]

Common Mistakes:

• Assuming wrong role still shows content
• Expecting server error on role mismatch
• Thinking partial access is automatic

4. Consider this Flask code snippet:

@app.route('/admin')
@role_required('admin')
def admin_panel():
    return 'Admin Panel'

Which of the following is a common mistake that would cause this role check to fail?

medium

A. Not importing the role_required decorator

B. Using @app.route after @role_required

C. Returning a string instead of JSON

D. Defining the function without parentheses

Solution

1. Step 1: Check decorator usage

   role_required must be imported to work; missing import causes failure.

2. Step 2: Verify other options

   @app.route order is flexible; returning string is valid; function definition syntax is correct.

3. Final Answer:

   Not importing the role_required decorator -> Option A

4. Quick Check:

   Missing import breaks decorator [OK]

Hint: Always import decorators before use [OK]

Common Mistakes:

• Assuming decorator order always matters
• Confusing return type with access control
• Syntax errors in function definition

5. You want to create a Flask route /settings that only users with roles 'admin' or 'manager' can access. Which code snippet correctly implements this role-based access control?

hard

A. @app.route('/settings')
@role_required('admin')
@role_required('manager')
def settings():
return 'Settings Page'

B. @app.route('/settings')
def settings():
if current_user.role in ['admin', 'manager']:
return 'Settings Page'
return 'Access Denied'

C. @app.route('/settings')
@role_required(['admin', 'manager'])
def settings():
return 'Settings Page'

D. @app.route('/settings')
@role_required('admin' or 'manager')
def settings():
return 'Settings Page'

Solution

1. Step 1: Analyze multiple role checks

   @app.route('/settings')
   @role_required('admin')
   @role_required('manager')
   def settings():
       return 'Settings Page'

   stacks decorators, which requires both roles simultaneously, not either/or.

2. Step 2: Check list role check in decorator

   @app.route('/settings')
   @role_required(['admin', 'manager'])
   def settings():
       return 'Settings Page'

   assumes role_required accepts list, which may not be supported by default.

3. Step 3: Evaluate logical or misuse

   @app.route('/settings')
   @role_required('admin' or 'manager')
   def settings():
       return 'Settings Page'

   uses 'admin' or 'manager' which evaluates to 'admin' always, incorrect.

4. Step 4: Confirm manual role check

   @app.route('/settings')
   def settings():
       if current_user.role in ['admin', 'manager']:
           return 'Settings Page'
       return 'Access Denied'

   manually checks if user role is in allowed list, correctly allowing either role.

5. Final Answer:

   Option B code with manual role check -> Option B

6. Quick Check:

   Manual role list check allows multiple roles [OK]

Hint: Use if-check for multiple roles if decorator lacks list support [OK]

Common Mistakes:

• Stacking decorators for multiple roles (AND instead of OR)
• Passing list directly to decorator without support
• Using 'or' inside decorator argument incorrectly