Session handling in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Rails controller action regarding session?

Consider this Rails controller action:

def login
  session[:user_id] = 42
  render plain: session[:user_id]
end

What will be the response body when this action is called?

Ruby on Rails

def login
  session[:user_id] = 42
  render plain: session[:user_id]
end

A "nil"

B "42"

C "session[:user_id]"

D "user_id"

💡 Hint

Remember, session stores values as key-value pairs accessible by keys.

The session[:user_id] is set to 42, so rendering session[:user_id] outputs "42" as a string.

❓ state_output

intermediate

What is the session content after this sequence?

Given this sequence in a Rails controller:

session[:cart] = ['apple']
session[:cart] << 'banana'
session[:cart].delete('apple')

What is the value of session[:cart] after these lines?

Ruby on Rails

session[:cart] = ['apple']
session[:cart] << 'banana'
session[:cart].delete('apple')

A ['banana']

B ['apple', 'banana']

C []

D ['apple']

💡 Hint

Think about how arrays change with << and delete methods.

Initially cart has ['apple'], then 'banana' is added, then 'apple' is removed, leaving ['banana'].

📝 Syntax

advanced

Which option correctly sets a flash message in Rails session?

Which of these lines correctly sets a flash notice message in a Rails controller?

A session[:flash] = "Welcome!"

B session.flash[:notice] = "Welcome!"

C flash.notice = "Welcome!"

D flash[:notice] = "Welcome!"

💡 Hint

Flash messages use a special hash called flash.

flash is a hash-like object; setting flash[:notice] = "Welcome!" is correct syntax.

🔧 Debug

advanced

Why does this session assignment not persist across requests?

In a Rails controller, this code is used:

def set_user
  user = User.find(params[:id])
  session[:user] = user
  render plain: "User set"
end

Why might session[:user] not persist correctly across requests?

Ruby on Rails

def set_user
  user = User.find(params[:id])
  session[:user] = user
  render plain: "User set"
end

A Because User.find returns nil if user not found, causing session to clear

B Because session[:user] key is reserved and cannot be used

C Because session can only store simple data types, not ActiveRecord objects

D Because render plain disables session storage

💡 Hint

Think about what kind of data can be stored in session.

Sessions store simple data like strings or numbers. Storing complex objects like ActiveRecord instances causes issues.

🧠 Conceptual

expert

What is the main security risk of storing sensitive data in Rails session?

Why is it risky to store sensitive information like passwords or credit card numbers directly in Rails session?

A Because session data is stored client-side and can be tampered with if not encrypted

B Because sessions automatically expire after 5 minutes, losing data

C Because Rails encrypts session data making it impossible to read later

D Because storing data in session causes server crashes under load

💡 Hint

Consider where session data is stored and how it can be accessed.

Rails stores session data in cookies by default, which are client-side and can be read or modified if not properly secured.