Session handling in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a session value in a Rails controller.

Ruby on Rails

session[:user_id] = [1]

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

Aflash[:user_id]

Bparams[:user_id]

Ccookies[:user_id]

Drequest.user_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using cookies or flash instead of params to set session data.

Trying to assign a method call that doesn't return the user ID.

In Rails, session values are usually set from parameters received in the request, such as params[:user_id].

2fill in blank

medium

Complete the code to retrieve the current user ID from the session in a Rails controller.

Ruby on Rails

current_user_id = session[1]

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

A[:user_id]

B['user_id']

C.user_id

D(user_id)

Attempts:

3 left

💡 Hint

Common Mistakes

Using string keys instead of symbols.

Using dot notation which is invalid for session hash.

Session keys in Rails are accessed using symbols inside square brackets, like session[:user_id].

3fill in blank

hard

Fix the error in the code to clear the session in a Rails controller.

Ruby on Rails

def logout
  [1]
  redirect_to root_path
end

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

Asession.delete(:user_id)

Bsession.destroy

Csession.reset

Dsession.clear

Attempts:

3 left

💡 Hint

Common Mistakes

Using session.delete which removes only one key.

Using session.destroy which is not a valid method.

To clear all session data in Rails, use session.clear. Other methods either delete a single key or do not exist.

4fill in blank

hard

Fill both blanks to check if a user is logged in by verifying the session key.

Ruby on Rails

if session[1] && session[2] != nil
  # user is logged in
end

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

A[:user_id]

B['user_id']

C.user_id

D(user_id)

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing string and symbol keys.

Using dot notation which is invalid.

To check if a user is logged in, verify the presence of session[:user_id]. Using symbol keys consistently is best practice.

5fill in blank

hard

Fill all three blanks to create a session hash storing user name and role if the user is admin.

Ruby on Rails

if params[:role] == 'admin'
  session[1] = params[:name]
  session[2] = params[:role]
  flash[:notice] = 'Admin logged in as ' + session[3]
end

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

A[:user_name]

B[:user_role]

D[:admin]

Attempts:

3 left

💡 Hint

Common Mistakes

Using different keys for storing and retrieving the user name.

Using invalid keys like :admin which is not set.

Store the user's name in session[:user_name] and role in session[:user_role]. Use the same key to display the name in the flash message.

Practice

1. What is the main purpose of using session in a Rails application?

easy

A. To style the webpage dynamically

B. To handle file uploads

C. To connect to the database

D. To store user data across multiple requests

Solution

1. Step 1: Understand what sessions do

   Sessions keep data between different pages or requests for the same user.

2. Step 2: Identify the correct purpose

   Storing user data like login status or preferences is the main use of sessions.

3. Final Answer:

   To store user data across multiple requests -> Option D

4. Quick Check:

   Sessions remember user info across pages = B [OK]

Hint: Sessions keep user info between pages [OK]

Common Mistakes:

• Confusing sessions with styling or database connections
• Thinking sessions handle file uploads

2. Which of the following is the correct way to store a user's name in the session in Rails?

easy

A. session = { name: 'Alice' }

B. session[:name] = 'Alice'

C. session.name = 'Alice'

D. session('name') = 'Alice'

Solution

1. Step 1: Recall session syntax in Rails

   Sessions use a hash-like syntax with square brackets and symbols for keys.

2. Step 2: Match the correct syntax

   Assigning with session[:name] = 'Alice' is the proper way.

3. Final Answer:

   session[:name] = 'Alice' -> Option B

4. Quick Check:

   Use session[:key] = value syntax = A [OK]

Hint: Use session[:key] = value to store data [OK]

Common Mistakes:

• Using assignment with equals on session itself
• Trying to call session like a method
• Using dot notation which is invalid

3. What will be the output of the following Rails controller code snippet?

session[:count] ||= 0
session[:count] += 1
render plain: session[:count]

medium

A. nil

B. 0

C. 1

D. Error

Solution

1. Step 1: Understand the ||= operator

   If session[:count] is nil or false, it sets it to 0; otherwise, it keeps the value.

2. Step 2: Increment the count

   After setting to 0 if needed, it adds 1, so the value becomes 1.

3. Final Answer:

   1 -> Option C

4. Quick Check:

   Initialize or keep count, then add 1 = 1 [OK]

Hint: ||= sets default, then += increments [OK]

Common Mistakes:

• Thinking ||= 0 sets count to 0 every time
• Expecting output 0 instead of 1
• Assuming session[:count] is nil after increment

4. Identify the error in this Rails controller code that tries to clear the session:

def logout
  session.clear()
  redirect_to root_path
end

medium

A. No error; code correctly clears the session

B. Missing parentheses in session.clear call

C. session.clear should be session.delete_all

D. session.clear is not a valid method

Solution

1. Step 1: Check session clearing methods in Rails

   Rails session supports clear method to remove all keys.

2. Step 2: Verify syntax and usage

   Calling session.clear() is valid and clears the session.

3. Final Answer:

   No error; code correctly clears the session -> Option A

4. Quick Check:

   session.clear() clears session correctly = D [OK]

Hint: session.clear() empties session data correctly [OK]

Common Mistakes:

• Thinking session.clear() is invalid
• Confusing with database delete methods
• Assuming parentheses are mandatory or cause error

5. You want to store a user's preferred language in the session only if it is not already set. Which code snippet correctly does this in a Rails controller?

hard

A. All of the above

B. session[:language] ||= params[:language]

C. session[:language] = params[:language] if session[:language].nil?

D. session[:language] = params[:language] unless session[:language]

Solution

1. Step 1: Understand the goal

   We want to set session[:language] only if it is not already set.

2. Step 2: Analyze each option

   session[:language] = params[:language] if session[:language].nil? uses if session[:language].nil?, which sets only if nil.
   session[:language] ||= params[:language] uses ||= which sets if false or nil.
   session[:language] = params[:language] unless session[:language] uses unless session[:language], which sets if false or nil.
   All three effectively do the same thing.

3. Final Answer:

   All of the above -> Option A

4. Quick Check:

   All three set only if session[:language] is unset = C [OK]

Hint: ||= or conditional assignment both work [OK]

Common Mistakes:

• Thinking only ||= works
• Confusing unless with if
• Setting session unconditionally