Mailer generation and templates in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this mailer method?

Given the following Rails mailer method, what will be the subject line of the sent email?

Ruby on Rails

class UserMailer < ApplicationMailer
  def welcome_email(user)
    @user = user
    mail(to: @user.email, subject: "Welcome to Our Site")
  end
end

# Assume user.email = '[e-mail]'

# When UserMailer.welcome_email(user).deliver_now is called

A "Welcome Email"

B "Welcome to Our Site"

C "Hello from Our Site"

D "UserMailer Notification"

💡 Hint

Look at the subject argument inside the mail method.

The subject line is set explicitly in the mail method call as "Welcome to Our Site".

📝 Syntax

intermediate

Which option correctly defines a mailer template file name?

In Rails, which filename correctly matches the mailer method 'notification_email' in 'UserMailer' for an HTML email template?

A app/views/user_mailer/notification_email.html

B app/views/user_mailer/notification_email.html.haml

C app/views/user_mailer/notification_email.erb

D app/views/user_mailer/notification_email.html.erb

💡 Hint

Rails expects template files to have the mailer method name and format with extension.

Rails mailer templates for HTML emails use the pattern: mailer_name/method_name.html.erb.

🔧 Debug

advanced

Why does this mailer raise an error?

Examine this mailer method and identify the cause of the error when sending the email.

Ruby on Rails

class UserMailer < ApplicationMailer
  def alert_email(user)
    @user = user
    mail(to: user.email, subject: "Alert") do |format|
      format.html
      format.text
    end
  end
end

# Error: Missing template user_mailer/alert_email.html.erb

A No template file named alert_email.html.erb exists in user_mailer views folder

B The mail method is missing the 'from' parameter

C The block syntax with format is invalid in mail method

D The user variable is not defined inside the method

💡 Hint

Check the error message about missing template.

Rails requires a matching template file for each format declared; missing alert_email.html.erb causes the error.

❓ state_output

advanced

What is the value of @greeting in this mailer template?

Given this mailer method and template, what will be the rendered value of @greeting in the email?

Ruby on Rails

class UserMailer < ApplicationMailer
  def custom_email(user)
    @greeting = "Hello, #{user.name}!"
    mail(to: user.email, subject: "Custom Greeting")
  end
end

# Template: app/views/user_mailer/custom_email.html.erb
# <p><%= @greeting %></p>

# Assume user.name = 'Alice'

A "Hello, Alice!"

B "Hello, user.name!"

C "Hello, !"

D "Hello, #{user.name}!"

💡 Hint

Instance variables set in the mailer method are available in the template.

The @greeting variable is set with string interpolation using user.name, so it renders as "Hello, Alice!".

🧠 Conceptual

expert

Which option best describes how Rails mailers handle multipart emails?

How does Rails decide which email format (HTML or text) to send when a mailer defines both formats in its template?

A Rails sends only the text part if both templates exist, ignoring the HTML part

B Rails sends only the HTML part if both templates exist, ignoring the text part

C Rails sends a multipart email containing both HTML and text parts; the email client chooses which to display

D Rails randomly sends either the HTML or text part each time the email is sent

💡 Hint

Think about how email clients handle different content types.

Rails automatically creates a multipart email with both HTML and text parts if both templates exist, letting the client pick the best format.