Enviando e-mails a los participantes

What is the ActionMailer in Rails?

In the Ruby on Rails world, the ActionMailer is an essential module that allows you to send emails to users automatically. This tool is essential for notifying participants when, for example, a new task has been created in our application. Before you start using ActionMailer, it is important that you review the necessary data and have your development environment ready to move forward.

How to create a Mailer in Rails?

To start sending emails, we must first generate a Mailer. We will use the well known Rails generator, rails generate, parameterized with mailer. This will generate the directory and file structure needed to create the email. In this case, we will call the ParticipantMailer email system. When using the command, several directories and files are created, among them, the main ParticipantMailer file, where we will develop the logic for sending the email.

rails generate mailer ParticipantMailer

How to edit the Mailer file?

Inside the ParticipantMailer file, we can create methods as if they were controller actions. These methods are associated to views that will render the email. We are going to create a method called new_tasks_email that, by means of variables, will transmit information to the view.

class ParticipantMailer < ApplicationMailer def new_tasks_email(user, task) @user = user @task = task mail(to: @user.email, subject: 'New task assigned') endend end

How to invoke the Mailer from the task model?

It is essential to call the Mailer once a new task has been created. To achieve this, we use an after_create callback in the Task model. This callback will call the mailer method we have defined.

class Task < ApplicationRecord after_create :send_email
 private
 def send_email participants = self.participants + [self.owner] participants.each do |user| ParticipantMailer.with(user: user, task: self).new_tasks_email.deliver_later end endend end end end

How to create a view for the email?

The email view is the HTML structure that will be sent to the users. We use the new_tasks_email.html.haml file to define the content of the email.

%h1 Hello, #{@user.email}%p You have a new task:%ul %li= "Name: #{@task.name}" %li= "Description: #{@task.description}" %li= "Category: #{@task.category.name}" %li= "View task at the following link:  #{link_to 'View task', task_path(@task)}"

Previewing mails with Letter Opener

To check and preview mails without sending actual messages, we use the letter_opener gem. This gem allows to open the mails in the browser, providing a safe environment for testing and tuning.

Letter Opener Configuration

1. Add letter_opener to the development group in your Gemfile:

   group :development do gem 'letter_opener'end

2. Configure the development environment in config/environments/development.rb:

   Rails.application.configure do config.action_mailer.delivery_method = :letter_opener config.action_mailer.perform_deliveries = true config.action_mailer.raise_delivery_errors = true config.action_mailer.default_url_options = { host: 'localhost', port: 3000 }end

Make sure to install the gem and restart the server:

bundle installrails server

Now, you can create a new task from your application interface and verify that the mails are generated correctly in the browser, thanks to letter_opener. This not only makes it easier to preview, but also to detect errors and style tests in your emails.

Go ahead, deepen your Rails knowledge and discover all that ActionMailer has to offer!