Rails cheatsheet to implement common features 🛤️

rails-cheatsheet.md

Rails Cheatsheet

• Authentication & Devise
• JavaScript
  • Stimulus
  • External libraries
  • AJAX
• Geocoding

Authentication & Devise

See the Devise repository for more information.

1. Add gem "devise" to the Gemfile and run:

   bundle install
   rails generate devise:install

   Then follow the instructions displayed in the terminal.

2. Generate a devise model with rails generate devise User.

3. Protect every route by default:

   # app/controllers/application_controller.rb
   
   class ApplicationController < ActionController::Base
     before_action :authenticate_user!
   end

4. Skip the login for some pages:

   # app/controllers/pages_controller.rb
   
   class PagesController < ApplicationController
     skip_before_action :authenticate_user!, only: :home
   
     def home
     end
   end

5. When adding new attributes to a devise model, specify them in the ApplicationController:

   # app/controllers/application_controller.rb
   
   class ApplicationController < ActionController::Base
     # [...]
     before_action :configure_permitted_parameters, if: :devise_controller?
   
     def configure_permitted_parameters
       # For additional fields in app/views/devise/registrations/new.html.erb
       devise_parameter_sanitizer.permit(:sign_up, keys: [:first_name, :last_name])
   
       # For additional in app/views/devise/registrations/edit.html.erb
       devise_parameter_sanitizer.permit(:account_update, keys: [:first_name, :last_name])
     end
   end

6. Optionally customize devise routes.

JavaScript

See the JavaScript in Rails guide for more information.

Stimulus

Generate Stimulus controllers with:

rails generate stimulus CONTROLLER_NAME

External libraries

importmap pin $NAME_OF_THE_LIBRARY

For example, to use flatpickr.js:

1. Install the library and import the stylesheet in your main layout:

   importmap pin flatpickr

   <!-- app/views/layouts/application.html.erb -->
   
   <!-- ... -->
   <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/flatpickr/dist/flatpickr.min.css">

2. Create a specific datepicker controller:

   rails generate stimulus datepicker

   // app/javascript/controllers/datepicker_controller.js
   
   import { Controller } from '@hotwired/stimulus'
   import flatpickr from 'flatpickr';
   
   export default class extends Controller {
     connect() {
       flatpickr(this.element)
     }
   }

3. Add the controller to the view:

   <%= f.input :opening_date,
       as: :string,
       input_html: { 
         data: { 
           controller: "datepicker" 
         } 
       }
   %>

AJAX

1. Set up the controller to return a JSON response using respond_to:

   # app/controllers/monuments_controller.rb
   
   # [...]
   def create
     @monument = Monument.new(monument_params)
   
     respond_to do |format|
       if @monument.save
         format.html { redirect_to monument_path(@monument) }
         format.json # looks for a create.json view
       else
         format.html { render "monuments/new", status: :unprocessable_entity }
         format.json # looks for a create.json view
       end
     end
   end

2. Make sure that the jbuilder gem is installed and create a create.json.jbuilder view:

   # app/views/monuments/create.json.jbuilder
   
   if @monument.persisted?
     json.form render(partial: "monuments/form", formats: :html, locals: { monument: Monument.new })
     json.inserted_item render(partial: "monuments/monument", formats: :html, locals: { monument: @monument })
   else
     json.form render(partial: "monuments/form", formats: :html, locals: { monument: @monument })
   end

3. Generate a new Stimulus controller to handle the request:

   rails generate stimulus insert_in_list

   // app/javascript/controllers/insert_in_list_controller.js
   
   import { Controller } from '@hotwired/stimulus'
   
   export default class extends Controller {
     static targets = ['items', 'form']
   
     send(event) {
       event.preventDefault();
   
       fetch(this.formTarget.action, {
         method: 'POST',
         headers: { Accept: 'application/json' },
         body: new FormData(this.formTarget)
       })
         .then(response => response.json())
         .then((data) => {
           if (data.inserted_item) {
             this.itemsTarget.insertAdjacentHTML('beforeend', data.inserted_item)
           }
           this.formTarget.outerHTML = data.form
         })
     }
   }

4. Connect the controller to the DOM:

   <!-- app/views/monument/index.html.erb -->
   
   <div class="container">
     <div class="row">
       <div class="col" data-controller="insert-in-list">
         <div id="monuments" data-insert-in-list-target="items">
           <!-- ... -->
         </div>
       </div>
     </div>
   </div>

   <!-- app/views/monument/_form.html.erb -->
   
   <%= simple_form_for monument,
       data: {
         insert_in_list_target: "form",
         action: "submit->insert-in-list#send"
       } do |f| %>
     <!-- ... -->
   <% end %>

Geocoding

1. Install and configure the geocoder gem:

   # Gemfile
   
   # ...
   gem "geocoder"

   bundle install
   rails generate geocoder:config

   # config/initializers/geocoder.rb
   Geocoder.configure(
     # [...]
     units: :km, # Defaults to miles (:mi)
   )

2. Add the coordinates columns and update the model:

   rails g migration AddCoordinatesToFlats latitude:float longitude:float
   rails db:migrate

   # app/models/flat.rb
   
   class Flat < ApplicationRecord
     geocoded_by :address
     after_validation :geocode, if: :will_save_change_to_address?
   end

3. Create a geocoded instance and search for nearby instances:

   # rails console
   Flat.create(address: "16 Villa Gaudelet, Paris", name: "Le Wagon HQ")
   # => #<Flat:0x007fad2e720898
   # id: 1,
   # name: "Le Wagon HQ",
   # address: "16 Villa Gaudelet, Paris",
   # latitude: 48.8649574,
   # longitude: 2.3800617>
   
   Flat.near("Tour Eiffel", 10)   # flats within 10 km of Tour Eiffel
   Flat.near([40.71, 100.23], 20) # flats within 20 km of a point