Rails 5: The Tour - Step by Step

cloud9-setup.sh

#!/bin/sh

# Clean workspace
rm -rf *
rm .gitignore

# Upgrade Ruby
rvm install ruby-2.4.1 --default

# Start PostgreSQL and fix encoding conflict when creating database
sudo service postgresql start
psql -c "UPDATE pg_database SET datistemplate='false' WHERE datname='template1';" 
psql -c "DROP DATABASE template1;"
psql -c "CREATE DATABASE template1 encoding='UTF8' template template0;"
psql -c "UPDATE pg_database SET datistemplate='true' WHERE datname='template1';"

tutorial.md

Rails 5: The Tour - Step by Step

Prerequisites

• Watch Rails 5: The Tour video.
• Create a Cloud9 account.
• Create a new Cloud9 Workspace using the Ruby template and run the following command from the terminal to setup everyting:

curl -sL https://git.io/v9bfL | bash; rvm use ruby-2.4.1

• Install Ruby on Rails gem:

gem install rails

App creation

Start the new weblog application:

rails new weblog --database postgresql --skip-coffee

Go the app folder:

cd weblog

Have a look at the rails command options:

rails --help

Start the rails server (in a separate terminal tab) and preview the running application on https://***.c9users.io:

rails server

Yay! You’re on Rails! 🎉

Post model

Generate a post scaffold and have a look at all the files generated:

rails generate scaffold post title:string body:text

Create and migrate the database:

rails db:create
rails db:migrate

Visit http://***.c9users.io/posts/new and create a new post. You can give a try to http://***.c9users.io/posts.json, yeah JSON API for free!

Add a title presence validation to the Post model and try to create a new post without a title (don't forget to save you file!):

# app/models/post.rb
class Post < ApplicationRecord
  validates :title, presence: true
end

Play with the rails console and try to create/load a post:

rails console
Post.all
Post.last
Post.create! title: 'Learnin Ruby on Rails', body: 'Oh Yeah!'
Post.last

Generate a new comment resource referencing the post model and run the migration:

rails generate resource comment post:references body:text
rails db:migrate

Comment model

Nest the comments resources route in posts resources and have a look at all the routes with rails routes:

# config/routes.rb
Rails.application.routes.draw do
  resources :posts do
    resources :comments
  end
end

Add the comments relationship in the Post model:

# app/models/post.rb
class Post < ApplicationRecord
  has_many :comments, dependent: :destroy

  validates :title, presence: true
end

Add a comments section on the show post template:

<%# app/views/posts/show.html.erb %>
<p id="notice"><%= notice %></p>

<p>
  <strong>Title:</strong>
  <%= @post.title %>
</p>

<p>
  <strong>Body:</strong>
  <%= @post.body %>
</p>

<%= link_to 'Edit', edit_post_path(@post) %> |
<%= link_to 'Back', posts_path %>

<br><br>

<h2>Comments</h2>

<div id="comments">
  <%# Expands to render partial: 'comments/comment', collection: @post.comments %>
  <%= render @post.comments %>
</div>

<%= render 'comments/new', post: @post %>

Add comments _comment.html.erb and _new.html.erb view partials:

<%# app/views/comments/_comment.html.erb %>
<p><%= comment.body %> -- <%= comment.created_at.to_s(:long) %></p>

<%# app/views/comments/_new.html.erb %>
<%= form_with(model: [@post, Comment.new], remote: true) do |form| %>
  Your comment:<br>
  <%= form.text_area :body, size: '50x20' %><br>
  <%= form.submit %>
<% end %>

Create a new create action in the CommentsController:

# app/controllers/comments_controller.rb
class CommentsController < ApplicationController
  before_action :set_post

  # POST /posts/:post_id/comments
  # POST /posts/:post_id/comments.json
  def create
    @post.comments.create!(comments_params)
    redirect_to @post
  end

  private
    def set_post
      @post = Post.find(params[:post_id])
    end

    def comments_params
      params.require(:comment).permit(:body)
    end
end

Now you can try to add a comment to an existing post on http://***.c9users.io/posts/1, please have a look at the rails server logs to see what is happening.

Comments mailer

Generate a new comments mailer with a submitted mail view:

rails generate mailer comments submitted

Edit the freshly created CommentsMailer:

# app/mailers/comments_mailer.rb
class CommentsMailer < ApplicationMailer

  # Subject can be set in your I18n file at config/locales/en.yml
  # with the following lookup:
  #
  #   en.comments_mailer.submitted.subject
  #
  def submitted(comment)
    @comment = comment

    mail to: "blog-owner@example.org", subject: 'New comment!'
  end
end

Edit the comments mailer view templates:

<%# app/views/comments_mailer/submitted.html.erb %>
<h1>You got a new comment on <%= @comment.post.title %></h1>

<%= render @comment %>

<%# app/views/comments_mailer/submitted.text.erb %>
You got a new comment on <%= @comment.post.title %>: <%= @comment.body %>

Edit the CommentsMailerPreview and preview a submitted email by visiting https://***.c9users.io/rails/mailers/comments_mailer/submitted

# test/mailers/previews/comments_mailer_preview.rb
class CommentsMailerPreview < ActionMailer::Preview
  def submitted
    CommentsMailer.submitted(Comment.first)
  end
end

Now that your email is ready we can send it after the comment creation in the CommentsController:

  def create
    comment = @post.comments.create!(comments_params)
    CommentsMailer.submitted(comment).deliver_later

    redirect_to @post
  end

Try to create a new comment from the browser and look at the server logs, you should see the email content ✉️.

Comments channel

Generate a new comments channel:

rails generate channel comments

Add a self.broadcast class method to the new CommentsChannel class:

# app/channels/comments_channel.rb
class CommentsChannel < ApplicationCable::Channel
  def self.broadcast(comment)
    broadcast_to comment.post, comment:
      CommentsController.render(partial: 'comments/comment', locals: { comment: comment })
  end

  def subscribed
    # Only stream the last post for the demo!
    stream_for Post.last
  end

  def unsubscribed
    # Any cleanup needed when channel is unsubscribed
  end
end

Edit the comments channel javascript file to append any new comment to the post show page:

// app/assets/javascripts/channels/comments.js
App.comments = App.cable.subscriptions.create("CommentsChannel", {
  connected: function() {
    // Called when the subscription is ready for use on the server
    console.log('connected');
  },

  disconnected: function() {
    // Called when the subscription has been terminated by the server
    console.log('disconnected');
  },

  received: function(data) {
    // Called when there's incoming data on the websocket for this channel
    console.log('received: ');
    console.log(data);
    document.getElementById('comments').innerHTML += data.comment;
  }
});

Broadcast the new comment from CommentsController#create:

def create
  comment = @post.comments.create!(comments_params)
  CommentsMailer.submitted(comment).deliver_later
  CommentsChannel.broadcast(comment)

  redirect_to @post
end

All set! Now open the last post from https://***.c9users.io/posts on two different browsers/tabs and try to create a comment on one of them ✨. (protip: Have a look at the browser inspector and the rails server log!)