Action Mailer setup in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when you call deliver_now on a mailer method?

Consider a Rails mailer method that sends an email. What is the behavior when you call deliver_now on the mailer method?

Ruby on Rails

UserMailer.welcome_email(user).deliver_now

A The email is sent immediately during the current request.

B The email is discarded and not sent.

C The email is saved to the database but not sent.

D The email is queued to be sent later by a background job.

💡 Hint

Think about synchronous vs asynchronous email sending.

deliver_now sends the email immediately during the current request cycle, blocking until the email is sent.

📝 Syntax

intermediate

Which option correctly sets the default 'from' email in a mailer class?

In a Rails mailer class, how do you set the default sender email address for all emails?

Ruby on Rails

class UserMailer < ApplicationMailer
  # set default from here
end

A from default: '[e-mail]'

B set_default from: '[e-mail]'

C default_from '[e-mail]'

D default from: '[e-mail]'

💡 Hint

Look for the correct method name and syntax for setting defaults.

The correct syntax is default from: 'email' inside the mailer class.

🔧 Debug

advanced

Why does this mailer method raise an error?

Given the following mailer method, why does calling UserMailer.notify(user).deliver_now raise an error?

Ruby on Rails

class UserMailer < ApplicationMailer
  def notify(user)
    mail(to: user.email, subject: 'Notification') do |format|
      format.text { render plain: 'Hello!' }
      format.html { render html: '<strong>Hello!</strong>'.html_safe }
    end
  end
end

A The block passed to <code>mail</code> is missing a closing <code>end</code>.

B The <code>html_safe</code> method is not allowed inside mailer views.

C The <code>render html:</code> call requires a template, not a string.

D The mailer method is missing a <code>return</code> statement.

💡 Hint

Check how render works inside mailers.

render html: expects a template or partial, not a raw string. To send raw HTML, use format.html { render inline: ... } or format.html { render html: ... } with safe HTML.

❓ state_output

advanced

What is the value of @greeting in the mailer view after calling this method?

Consider this mailer method:

def welcome(user)
  @greeting = "Hello, #{user.name}!"
  mail(to: user.email, subject: 'Welcome')
end

What will @greeting contain in the mailer view?

A The string "Hello, " followed by the user's name and an exclamation mark.

B Nil, because instance variables are not passed to mailer views.

C An empty string, since <code>@greeting</code> is not set in the view.

D The user's email address.

💡 Hint

Think about how instance variables work in mailers and views.

Instance variables set in the mailer method are available in the mailer views, so @greeting will contain the greeting string with the user's name.

🧠 Conceptual

expert

Which configuration is required to send emails asynchronously using Active Job with Action Mailer?

You want to send emails without blocking the web request by using background jobs. Which configuration and method call combination achieves this in Rails?

A Set <code>config.action_mailer.delivery_method = :sendmail</code> and call <code>deliver_now</code> on the mailer method.

B Set <code>config.action_mailer.delivery_method = :smtp</code> and call <code>deliver_later</code> on the mailer method.

C Set <code>config.action_mailer.perform_deliveries = false</code> and call <code>deliver_later</code> on the mailer method.

D Set <code>config.active_job.queue_adapter = :inline</code> and call <code>deliver_now</code> on the mailer method.

💡 Hint

Consider how to enable background job processing and which mailer method triggers async sending.

To send emails asynchronously, you must have a background job adapter configured (like Sidekiq or the default async adapter) and call deliver_later. The delivery method (like SMTP) must be set to actually send emails.