Sending emails from controllers in Ruby on Rails

Introduction

Sending emails from controllers lets your app notify users right after they do something, like signing up or ordering.

After a user signs up, send a welcome email.

When a user resets their password, send a reset link.

Notify admins when a new order is placed.

Send confirmation emails after a form submission.

Syntax

Ruby on Rails

UserMailer.welcome_email(@user).deliver_now

Use deliver_now to send the email immediately.

You call the mailer method with the data it needs, like a user object.

Examples

Sends the welcome email right away.

Ruby on Rails

UserMailer.welcome_email(@user).deliver_now

Sends the reset password email later using background jobs.

Ruby on Rails

UserMailer.reset_password_email(@user).deliver_later

Immediately notifies admins about a new order.

Ruby on Rails

AdminMailer.new_order_notification(order).deliver_now

Sample Program

This controller creates a user and sends a welcome email immediately after saving. The mailer defines the email details.

Ruby on Rails

class UsersController < ApplicationController
  def create
    @user = User.new(user_params)
    if @user.save
      UserMailer.welcome_email(@user).deliver_now
      redirect_to root_path, notice: "Welcome email sent!"
    else
      render :new
    end
  end

  private

  def user_params
    params.require(:user).permit(:email, :password, :password_confirmation)
  end
end

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

Important Notes

Use deliver_later to send emails asynchronously and avoid slowing down user actions.

Keep email sending logic in mailers, not controllers, for cleaner code.

Always test emails in development using tools like Letter Opener or Mailcatcher.

Summary

Controllers trigger emails by calling mailer methods with data.

Use deliver_now for immediate sending, deliver_later for background jobs.

Keep email content and setup inside mailers, not controllers.

Practice

1. What is the main role of a controller when sending emails in Rails?

easy

A. To call the mailer method and trigger the email sending

B. To write the email content and layout

C. To configure the SMTP settings

D. To store email templates in the database

Solution

1. Step 1: Understand controller responsibility

   Controllers handle user requests and trigger actions like sending emails by calling mailer methods.

2. Step 2: Identify mailer role

   Mailers contain email content and setup, not controllers.

3. Final Answer:

   To call the mailer method and trigger the email sending -> Option A

4. Quick Check:

   Controllers trigger mailers [OK]

Hint: Controllers trigger mailers, mailers build emails [OK]

Common Mistakes:

• Writing email content in controllers
• Configuring SMTP in controllers
• Storing templates in controllers

2. Which of the following is the correct syntax to send an email immediately from a controller using a mailer named UserMailer and a method welcome_email?

easy

A. UserMailer.welcome_email.deliver_later(params[:user])

B. UserMailer.welcome_email(params[:user]).deliver_now

C. UserMailer.deliver_now.welcome_email(params[:user])

D. UserMailer.welcome_email(params[:user]).send_now

Solution

1. Step 1: Identify mailer method call

   The mailer method is called with parameters: UserMailer.welcome_email(params[:user]).

2. Step 2: Use correct delivery method

   To send immediately, use deliver_now after the mailer method call.

3. Final Answer:

   UserMailer.welcome_email(params[:user]).deliver_now -> Option B

4. Quick Check:

   Immediate send = deliver_now after mailer call [OK]

Hint: Call mailer method then add .deliver_now for immediate send [OK]

Common Mistakes:

• Using deliver_later for immediate send
• Calling deliver_now before mailer method
• Using non-existent send_now method

3. Given this controller code snippet:

def create
  @user = User.new(user_params)
  if @user.save
    UserMailer.welcome_email(@user).deliver_later
    redirect_to root_path, notice: 'User created!'

What happens when this code runs successfully?

medium

A. The welcome email is sent immediately before redirecting

B. The redirect happens only after the email is sent

C. The welcome email is queued to be sent later, then redirect happens

D. The email is never sent because deliver_later is incorrect here

Solution

1. Step 1: Understand deliver_later behavior

   Calling deliver_later queues the email to be sent asynchronously in the background.

2. Step 2: Analyze controller flow

   The redirect happens immediately after queuing the email, not waiting for sending.

3. Final Answer:

   The welcome email is queued to be sent later, then redirect happens -> Option C

4. Quick Check:

   deliver_later queues email, redirect immediate [OK]

Hint: deliver_later queues email, does not block controller [OK]

Common Mistakes:

• Thinking deliver_later sends email immediately
• Assuming redirect waits for email sending
• Believing deliver_later is invalid syntax

4. Identify the error in this controller code snippet:

def notify
  UserMailer.notify_user.deliver_now(user)
  redirect_to dashboard_path
end

medium

A. deliver_now is not a valid method for sending emails

B. redirect_to should be called before sending email

C. notify_user method cannot be called without parentheses

D. deliver_now should be called after passing user argument to notify_user

Solution

1. Step 1: Check method call order

   The user argument must be passed to notify_user before calling deliver_now.

2. Step 2: Correct syntax

   Correct call: UserMailer.notify_user(user).deliver_now.

3. Final Answer:

   deliver_now should be called after passing user argument to notify_user -> Option D

4. Quick Check:

   Pass args before deliver_now [OK]

Hint: Pass arguments inside mailer method, then call deliver_now [OK]

Common Mistakes:

• Calling deliver_now with arguments
• Calling redirect_to before email
• Misusing parentheses in method calls

5. You want to send a confirmation email from a controller only if the user has a verified email address. Which is the best way to implement this?

hard

A. In the controller, check if user.verified? then call UserMailer.confirmation_email(user).deliver_now

B. Always call UserMailer.confirmation_email(user).deliver_now and check verification inside the mailer

C. Send the email unconditionally and add a condition in the email template

D. Call UserMailer.confirmation_email.deliver_now(user) without any condition

Solution

1. Step 1: Decide where to check condition

   Controller should decide if email should be sent based on user verification status.

2. Step 2: Call mailer only when condition is true

   Call UserMailer.confirmation_email(user).deliver_now only if user.verified? is true.

3. Final Answer:

   In the controller, check if user.verified? then call UserMailer.confirmation_email(user).deliver_now -> Option A

4. Quick Check:

   Check condition in controller before sending email [OK]

Hint: Check conditions in controller before calling mailer [OK]

Common Mistakes:

• Checking conditions inside mailer or template
• Sending emails unconditionally
• Passing arguments after deliver_now