So You Think You Can Rails

When I began coding with Rails only 3 weeks ago, I could state with confidence that I only understood about 20 percent of the reading material. The firehose of information was opened to max, and I had about two weeks to understand it all before our code challenge.

It was a lot of information, so I buckled down, read, and re-read the key READMEs, rewatched old lectures to the point that I found myself asking questions to my instructor from 4 days ago. In the end, I overcame, and passed! With this new albeit short feeling of triumph, I decided to write this post with some fundamental Rails commands to streamline your programming process.

Basic MVC Architecture

Model View Controller or MVC is a software design pattern for developing web applications.

• Model - Responsible for maintaining data.
• View - Presents all or some data to the User
• Controller - Responds to user input and performs interactions between models and views

Create a new application

Install the Rails gem if you haven't done so before

$ gem install rails

Generate a new Rails app

$ rails new my-app 

Initialize the database

$ rake db:create

Start the Rails server

$ rails s

Routes

Create a route that maps a URL to the controller action

# config/routes.rb
get 'welcome' => 'pages#home'

Shorthand for connecting a route to a controller/action

# config/routes.rb
get 'photos/show'

# The above is the same as: 
get 'photos/show', :to 'photos#show'
get 'photos/show' => 'photos#show'

Similarly, you can create all the RESTful routes for a resource by simply...

# config/routes.rb
resources :photos 

HTTP Verb	Path	Controller#Action	Used for
GET	/photos	photos#index	display a list of all photos
GET	/photos_new	photos#new	return an HTML form for creating a new photo
POST	/photos	photos#create	create a new photo
GET	/photos/:id	photos#show	display a specific photo
GET	/photos/:id/edit	photos#edit	return an HTML form for editing a photo
PATCH/PUT	/photos/:id	photos#update	update a specific photo
DELETE	/photos/:id	photos#destroy	delete a specific photo

Create resources for specific actions...

# config/routes.rb
resources :photos, only: [:index]

Create a route to a static view, without an action in the controller

# config/routes.rb
# If there's a file called 'about.html.erb' in 'app/views/photos', this file will be 
#   automatically rendered when you call localhost:3000/photos/about
get 'photos/about', to: 'photos#about'

Reference: http://guides.rubyonrails.org/routing.html

Controllers

Generate a new controller

Attention: Capitalize controller names and pluralize

$ rails g controller Photos

You can generate a new controller with default actions, routes and views

$ rails g controller Photos index show

Reference: http://guides.rubyonrails.org/action_controller_overview.html

Models

Generate a model and create a migration for each table

Attention: Capitalize model names and singular

$ rails g model Photo

Generate a model and create a migration with table columns

$ rails g model Photo location:string description:text

The migration automatically created for the above command:

class CreatePhotos < ActiveRecord::Migration
  def change
    create_table :photos do |t|
      t.string :location
      t.text :description

      t.timestamps null: false
    end
  end
end

Reference: http://guides.rubyonrails.org/active_model_basics.html

Migrations

Migration Data Types

• :boolean
• :date
• :datetime
• :decimal
• :float
• :integer
• :primary_key
• :references
• :string
• :text
• :time
• :timestamp

Scaffolding

Scaffolding is great for prototypes but don't rely too heavily on it. Here's a good explanation on why: http://stackoverflow.com/a/25140503

$ rails g scaffold Photo location:string description:text
$ rake db:migrate

Rake

View all the routes in an application

$ rake routes

Seed the database with sample data from db/seeds.rb

$ rake db:seed

Run any pending migrations

$ rake db:migrate

Rollback the last migration performed

ATTENTION: Keep in mind that this command is destructive and you could lose your data. Make sure you run any pending migrations and re-seed after making the appropriate changes.

$ rake db:rollback

...will rollback your migrations one step.

$ rake db:rollback STEP=n

...will rollback your migrations n number of steps.

Path Helpers

Creating a path helper for a route

# Creating a path helper for a route
get '/photos/:id', to: 'photos#show', as: 'photo'

# app/controllers/photos_controller.rb
def show
@photo = Photo.find(params[:id])
end

# View for the action
<%= link_to 'Photo View Page', photo_path(@photo) %>

Once again, path helpers are automatically created when specifying a resource in config/routes.rb

# config/routes.rb
resources :photos

For example, let's look at all the RESTful routes for photos

HTTP Verb	Path	Controller#Action	Named Helper
GET	/photos	photos#index	photos_path
GET	/photos/new	photos#new	new_photo_path
POST	/photos	photos#create	photos_path
GET	/photos/:id	photos#show	photo_path(:id)
GET	/photos/:id/edit	photos#edit	edit_photo_path(:id)
PATCH/PUT	/photos/:id	photos#update	photo_path(:id)
DELETE	/photos/:id	photos#destroy	photo_path(:id)

Form Helpers

Connect a form to a model for creating or updating a resource.

Use this method if you're using strong params to protect against mass assignment.
Some helpful documentation on strong params and mass assignment: https://ropesec.com/articles/mass-assignment/

# app/controllers/photos_controller.rb
def new
  @photo = Photo.new
end

# app/controllers/photos_controller.rb
def create
  @photo = Photo.new(params.require(:photo).permit(:description, :location)
Photo.save
redirect_to photo_path(@photo)
end

# ERB view
<%= form_for @photo do |f| %>
  <%= f.text_field :location %>
  <%= f.text_area :description, size: "60x12" %>
  <%= f.submit "Submit" %>
<% end %>

And there you have it! Use this guide to help you understand the different rails commands to help you create your MVC along with RESTful routes for your Models.

References: [http://guides.rubyonrails.org/form_helpers.html]
[http://www.pragtob.info/rails-beginner-cheatsheet/]