Mailer generation and templates in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to generate a new mailer named UserMailer.

Ruby on Rails

rails generate [1] UserMailer

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

Amodel

Bcontroller

Cmailer

Dscaffold

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'model' instead of 'mailer' will create a database model, not a mailer.

Using 'controller' creates a controller, not a mailer.

In Rails, to create a mailer, you use rails generate mailer followed by the mailer name.

2fill in blank

medium

Complete the mailer method definition to send a welcome email to a user.

Ruby on Rails

def welcome_email(user)
  @user = user
  mail(to: @user.email, subject: [1])
end

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

A:greeting

B:welcome

C"Hello"

D"Welcome to our site!"

Attempts:

3 left

💡 Hint

Common Mistakes

Using a symbol instead of a string for the subject.

Forgetting quotes around the subject text.

The subject option in the mail method expects a string for the email subject line.

3fill in blank

hard

Fix the error in the mailer view file to correctly display the user's name in the email.

Ruby on Rails

<p>Hello, [1]!</p>

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

A<% @user.name %>

B<%= @user.name %>

C{{ @user.name }}

D<%= user.name %>

Attempts:

3 left

💡 Hint

Common Mistakes

Using <% %> without equals sign does not output content.

Using wrong variable name without @.

In Rails mailer views, use <%= %> to output Ruby code. The instance variable @user holds the user object.

4fill in blank

hard

Fill both blanks to set the default sender email and layout in the mailer class.

Ruby on Rails

class UserMailer < ApplicationMailer
  [1] '[e-mail]'
  [2] 'mailer'
end

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

Adefault from:

Blayout

Cdefault sender:

Dtemplate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'default sender:' instead of 'default from:'.

Using 'template' instead of 'layout' for layout setting.

Use default from: to set the sender email and layout to specify the mailer layout.

5fill in blank

hard

Fill all three blanks to create a mailer method that sends a notification with a subject, recipient, and uses a template.

Ruby on Rails

def notification_email(user)
  @user = user
  mail([1]: @user.email, [2]: [3])
end

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

Ato

Bsubject

C"You have a new notification"

Dfrom

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up 'from' and 'to' options.

Not using quotes around the subject string.

The mail method takes to: for recipient email and subject: for the email subject string.

Practice

1. What is the primary purpose of a mailer in a Rails application?

easy

A. To send emails from the application

B. To handle database migrations

C. To manage user sessions

D. To style HTML templates

Solution

1. Step 1: Understand the role of mailers

   Mailers in Rails are designed to send emails from the application to users or other recipients.

2. Step 2: Differentiate from other components

   Database migrations handle schema changes, sessions manage user logins, and styling is done in views or CSS, not mailers.

3. Final Answer:

   To send emails from the application -> Option A

4. Quick Check:

   Mailer = send emails [OK]

Hint: Mailers send emails, not handle data or styling [OK]

Common Mistakes:

• Confusing mailers with controllers
• Thinking mailers manage database
• Assuming mailers style HTML

2. Which Rails command correctly generates a mailer named UserMailer?

easy

A. rails generate controller UserMailer

B. rails generate mailer UserMailer

C. rails generate model UserMailer

D. rails generate job UserMailer

Solution

1. Step 1: Identify the correct generator for mailers

   The command rails generate mailer UserMailer creates a mailer class and related files.

2. Step 2: Understand other generators

   Controllers handle web requests, models handle data, and jobs handle background tasks, so those commands are incorrect for mailers.

3. Final Answer:

   rails generate mailer UserMailer -> Option B

4. Quick Check:

   Mailer generator uses 'mailer' keyword [OK]

Hint: Use 'rails generate mailer' to create mailers [OK]

Common Mistakes:

• Using controller generator for mailers
• Confusing model and mailer generators
• Typing job instead of mailer

3. Given this mailer method:

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

What happens when UserMailer.welcome_email(@user).deliver_now is called?

medium

A. The email is queued but not sent immediately

B. The method returns a string with the email content but does not send it

C. An email is sent immediately to the user's email with subject 'Welcome!'

D. An error occurs because deliver_now is not a valid method

Solution

1. Step 1: Understand mailer method behavior

   The method welcome_email sets instance variables and calls mail to prepare the email.

2. Step 2: Effect of deliver_now

   Calling deliver_now sends the email immediately instead of queuing it.

3. Final Answer:

   An email is sent immediately to the user's email with subject 'Welcome!' -> Option C

4. Quick Check:

   deliver_now sends email immediately [OK]

Hint: deliver_now sends email immediately, deliver_later queues it [OK]

Common Mistakes:

• Thinking deliver_now only prepares email
• Confusing deliver_now with deliver_later
• Assuming deliver_now is invalid

4. Identify the error in this mailer template file named welcome_email.html.erb:

<h1>Welcome, <%= @user.name %>!</h1>
<p>Thanks for joining.</p>
<p>Your email is: <%= user.email %></p>

medium

A. The = sign is missing in the ERB tags

B. The HTML tags are incorrect and will cause rendering errors

C. The template file should be named welcome_email.text.erb

D. The variable user is undefined; should use @user

Solution

1. Step 1: Check variable usage in template

   The mailer method sets @user, so the template must use @user to access user data.

2. Step 2: Identify incorrect variable

   The template uses user.email which is undefined, causing an error.

3. Final Answer:

   The variable user is undefined; should use @user -> Option D

4. Quick Check:

   Use instance variables (@user) in mailer templates [OK]

Hint: Mailer templates use instance vars like @user, not local vars [OK]

Common Mistakes:

• Using local variables instead of instance variables
• Misnaming template files
• Forgetting <%= in ERB tags

5. You want to send a welcome email with both HTML and plain text versions. Which setup correctly supports this in Rails mailers?

hard

A. Create welcome_email.html.erb and welcome_email.text.erb templates in the mailer views folder

B. Create only welcome_email.html.erb template; Rails auto-generates text version

C. Create welcome_email.erb with mixed HTML and text content

D. Create welcome_email.text.erb only; HTML is optional

Solution

1. Step 1: Understand multi-format email templates

   Rails supports sending emails with both HTML and plain text by providing separate templates named with .html.erb and .text.erb extensions.

2. Step 2: Why both templates are needed

   Some email clients prefer plain text, so having both ensures compatibility and better user experience.

3. Final Answer:

   Create welcome_email.html.erb and welcome_email.text.erb templates in the mailer views folder -> Option A

4. Quick Check:

   Both .html.erb and .text.erb templates needed for multi-format emails [OK]

Hint: Use both .html.erb and .text.erb templates for emails [OK]

Common Mistakes:

• Assuming Rails auto-generates text version
• Mixing HTML and text in one template
• Skipping plain text template