Rails MVC by Sergiy Koshovyi

Model-View-Controller
Trygve Reenskaug. 1978

● Separation of business logic
● Reusing of code
● Separation of responsibility
● Flexible application
BENEFITS

● Doesn’t have a strict implementation
● No one place for busines logic
● No one place for validations
● No one place for views
PROPERTIES

Rails MVC
in the context
of user

MVC is an Architectural Pattern
8
My Banana
Stuart, give me
the banana
Ostap, are
you here?
I’m coming
put on a suit
Farewell !!!

Rails MVC
in the context
of components

10
Router
Controller ModelResponse
Views DataBase

Rails MVC
in the context
of Rails libraries

resource :profile, only: %i[show edit update], controller: :profile
14
RESOURCE

1 Rails.application.routes.draw do
2 root 'home#index'
3
4 resources :events, only: %i[index show] do
5 resources :visit_requests, only: %i[show create destroy]
6 end
15
RESOURCES

CUSTOM ROUTES WITHIN RESOURCES
1 resources :orders do
2 collection do
3 post :search
4 end
5 member do
6 post :accept
7 post :reject
8 post :ship
9 get :despatch_note
10 end
11 end
16

get '/:page_url', to: 'pages#show'
authenticate :user, ->(u) { u.admin? } do
namespace :admin do
get '/', to: 'home#index'
resources :accounts
17
CUSTOM ROUTES, NAMESPACE

1 # api
2 namespace :api, path: '/', constraints: { subdomain: 'api' }, defaults: { format: :json } do
3 namespace :v1 do
4 post 'sign_up' => 'registrations#create'
5 post 'sign_in' => 'sessions#create'
6 delete 'sign_out' => 'sessions#destroy'
7 end
8 end
18
NAMESPACES
api_v1_sign_up POST /v1/sign_up(.:format) api/v1/registrations#create
{:subdomain=>"api", :format=>:json}
api_v1_sign_in POST /v1/sign_in(.:format) api/v1/sessions#create
api_v1_sign_out DELETE /v1/sign_out(.:format) api/v1/sessions#destroy

1 # api
2 scope :api, constraints: { subdomain: 'api' }, module: :api, defaults: { format: :json }, as: :api do
3 scope '/v1', module: :v1, as: :v1 do
7 end
8 end
19
SCOPES
api_v1_sign_up POST /v1/sign_up(.:format) api/v1/registrations#create
api_v1_sign_in POST /v1/sign_in(.:format) api/v1/sessions#create
api_v1_sign_out DELETE /v1/sign_out(.:format) api/v1/sessions#destroy

20
Wait!
Aren’t namespaces and scopes essentially the same?

1 # api
2 scope :api do
3 scope :v1 do
7 end
8 end
21
SCOPES WITHOUT ANY OPTIONS
sign_up POST /sign_up(.:format) registrations#create
sign_in POST /sign_in(.:format) sessions#create
sign_out DELETE /sign_out(.:format) sessions#destroy

22
NAMESPACE vs SCOPE
Namespace Scope
By default, adds the name of the
namespace to the name of the path,
prefixes actual request path, and expects
the controller to belong to appropriately
named module.
No defaults. All options are explicit.
A shortcut method when you need to
quickly nest a set of routes and controllers
under some name.
A powerful, customizable method to apply
defaults to a group of routes.

1 namespace :admin do
2 root "admin#index"
3 end
4
5 root "home#index"
23
MULTIPLE ROOT ROUTES

1 constraints(id: /[A-Z][A-Z][0-9]+/) do
2 resources :photos
3 resources :accounts
4 end
24
CONSTRAINTS

1 def create
2 @product = Product.new(safe_params)
3 if @product.save
4 redirect_to :products, flash: { notice: t('shopr.products.create_notice') }
5 else
6 render action: 'new'
7 end
8 end
9
10 def update
11 if @product.update(safe_params)
12 redirect_to [:edit, @product], flash: { notice: t('products.update_notice') }
13 else
14 render action: 'edit'
15 end
16 end
26
DEFAULT ACTIONS

1 class ApplicationController < ActionController::Base
2 protect_from_forgery with: :exception
3 before_action :auth, only: :admin
4 helper_method :admin?, :about_page, :contacts_page
6 delegate :admin?, to: :current_user, allow_nil: true
7 skip_authorization_check
8 skip_before_action :authenticate_user!
27
HELPERS, BEFORE ACTIONS, ...

1 def create
2 @protocol = Protocol.create(protocol_params)
3 end
4
5 private
6
7 def protocol_params
8 params.require(:protocol).permit(
9 :competition_id,
10 :first_name,
11 :last_name,
12 :total_result,
13 :place
14 )
15 end
28
PERMITTED PARAMS

1 def create
2 @product = Product.new(safe_params)
3 if @product.save
4 redirect_to :products, flash: { notice: t('shopr.products.create_notice') }
5 else
6 render action: 'new'
7 end
8 end
29
REDIRECT VS RENDER

render :edit
render action: :edit
render "edit"
render "edit.html.erb"
render action: "edit"
render action: "edit.html.erb"
render "books/edit"
render "books/edit.html.erb"
30
RENDER
render template: "books/edit"
render template: "books/edit.html.erb"
render "/path/to/rails/app/views/books/edit"
render "/path/to/rails/app/views/books/edit.html.erb"
render file: "/path/to/rails/app/views/books/edit"
render file: "/path/to/rails/app/views/books/edit.html.erb"

1 def create
2 Shopr::Order.transaction do
3 @order = Shopr::Order.new(safe_params)
4 @order.status = 'confirming'
5 if safe_params[:customer_id]
6 @customer = Shopr::Customer.find safe_params[:customer_id]
7 @order.first_name = @customer.first_name
8 @order.last_name = @customer.last_name
9 @order.company = @customer.company
10 @order.email_address = @customer.email
11 @order.phone_number = @customer.phone
12 if @customer.addresses.billing.present?
13 billing = @customer.addresses.billing.first
14 @order.billing_address1 = billing.address1
18 @order.billing_postcode = billing.postcode
19 @order.billing_country_id = billing.country_id
31
FAT CONTROLLERS

1 class VisitRequestsController < ApplicationController
2 before_action :authenticate_user!, only: %i[create destroy]
3
4 def show
5 VisitRequest::FinalConfirmation.call(visit_request, params)
6 flash_success(visit_request.status) and default_redirect
7 end
8
9 def create
10 VisitRequest::Create.call(current_user, event)
11 flash_success and default_redirect
12 end
13
14 def destroy
15 visit_request.destroy
16 flash_success and default_redirect
17 end
32
THIN CONTROLLERS

1 class Goal < ApplicationRecord
2 has_many :donations, dependent: :destroy
3
4 validates :title, presence: true
5 validates :amount, presence: true, numericality: true
6
7 def achieved?
8 donations_total >= amount
9 end
10
11 def donations_total
12 donations.sum(:amount)
13 end
14 end
34
MODELS

class Goal < ApplicationRecord
has_many :donations, dependent: :destroy
end
class Donation < ApplicationRecord
belongs_to :goal
end
35
ONE TO MANY/ONE RELATIONS
Goal
id:integer
title:string
Donation
id:integer
goal_id:integer
title:string
...
...

36
MANY TO MANY RELATIONS
Goal
id:integer
title:string
Donation
id:integer
title:string
... ...
has_and_belongs_to_many :donations
end
has_and_belongs_to_many :goal
end
donations_goals
goal_id:integer
donation_id:integer

37
ASSOCIATION RELATIONS
Goal
id:integer
title:string
Donation
id:integer
goal_id:integer
...
...
has_many :donations
has_many :users, through: :donations
end
belongs_to :goal
belongs_to :user
end
class User < ApplicationRecord
has_many :donations
end
User
id:integer
email:string
...
user_id:integer

38
POLYMORPHIC RELATIONS
User
id:integer
email:string
Company
id:integer
name:string
... ...
Address
id:integer
address:string
addressable_id:integer
addressable_type:string
class Address < ApplicationRecord
belongs_to :addressable, polymorphic: true
end
class User < ApplicationRecord
has_many :address, as: :assressable
end
class Company < ApplicationRecord
has_many :address, as: :assressable
end

2 validates :title, presence: true
3 end
4
5 goal = Goal.create(title: “Buying a motocycle”).valid? # => true
6 goal = Goal.create(title: nil).valid? # => false
7 goal.errors.messages # => {title:["can't be blank"]}
39
VALIDATES

2 validates_associated :donations #(only in one of related model)
3 validates_with GoalValidator #class GoalValidator < ActiveModel::Validator
4 validate :expiration_date_cannot_be_in_the_past
5
6 def expiration_date_cannot_be_in_the_past
7 if expiration_date.present? && expiration_date < Date.today
8 errors.add(:expiration_date, "can't be in the past")
9 end
10 end
11 end
40
VALIDATES

1 <h2> <%= t 'goals.singular'> </h1>
2
3 < div class="col-md-12" >
4 <%= goal.title >
5 < /div>
7 <%= goal.description >
8 < /div>
10 <%= "Amount to reach: #{goal.amount}" >
11 < /div>
13 <%= "Current sum: #{goal.donations_total}" >
14 < /div>
42
TEMPLATES

1 <h2> <%= t 'goals.singular'> </h1>
2
4 <%= goal.title >
5 < /div>
7 <%= goal.description >
8 < /div>
10 <%= "Amount to reach: #{goal.amount}" >
11 < /div>
13 <%= "Current sum: #{goal.donations_total}" >
14 < /div>
43
.html.erb (ERB - Embedded Ruby)

1 h2 = t 'goals.singular'
2
3 .col-md-12
4 = goal.title
5 .col-md-12
6 = goal.description
7 .col-md-12
8 = "Amount to reach: #{goal.amount}"
9 .col-md-12
10 = "Current sum: #{goal.donations_total}"
11 .col-md-12
12 - unless goal.achieved?
13 = render 'shared/donations/form', path: donate_goal_path(goal)
44
.html.slim

1 $('#notifications_list').html(
2 "<%= escape_javascript(render('notifications/list', notifications: @notifications)) %>"
3 );
4
5 $('.container-fluid .flash-msg').html(
6 "<%= escape_javascript(render 'layouts/alerts') %>"
7 );
8
9 $("#send-notification-modal").modal("hide");
45
.js.erb

1 json.extract! ticket, :id,
:uid,
:manager_id,
:customer_name,
:customer_email,
:title,
:body,
:status_id
2 json.url ticket_url(ticket, format: :json)
46
.json.jbuilder

new.html.slim
1 = render 'shared/donations/form',
path: donate_goal_path(goal)
edit.html.slim
1 = render 'shared/donations/form',
path: donate_goal_path(goal)
47
PARTIALS
_form.html.slim
= simple_form_for :credit_card, url: path do |f|
.form-inputs
.row
.col-md-6
= f.input :number, as: :string
= f.input :cvc, as: :string
= f.input :exp_month, as: :string
= f.input :exp_year, as: :string

1 <h1>Listing Books</h1>
2 <table>
3 <tr>
4 <th>Title</th>
5 <th>Summary</th>
6 <th></th>
7 <th></th>
8 <th></th>
9 </tr>
10 <% @books.each do |book| %>
11 <tr>
12 <td><%= book.title %></td>
13 <td><%= book.content %></td>
14 <td><%= link_to "Show", book %></td>
15 <td><%= link_to "Edit", edit_book_path(book) %></td>
16 <td><%= link_to "Remove", book, method: :delete, data: { confirm: "Are you sure?" } %></td>
17 </tr>
18 <% end %>
19 </table>
48
PARTIALS. MAGIC

/views/books/index.html.erb
1 <h1>Listing Books</h1>
2 <table>
3 <tr>
4 <th>Title</th>
5 <th>Summary</th>
6 <th></th>
7 <th></th>
8 <th></th>
9 </tr>
10 <%= render @books %>
11 </table> 49
PARTIALS. MAGIC
/views/books/_book.html.erb
1 <tr>
2 <td><%= book.title %></td>
3 <td><%= book.content %></td>
4 <td><%= link_to "Show", book %></td>
5 <td><%= link_to "Edit", edit_book_path(book) %></td>
16 <td><%= link_to "Remove", book, method: :delete, data:
{ confirm: "Are you sure?" } %></td>
17 </tr>

class HomeController < ApplicationController
def index
render 'events/show'
end
end
51
LAYOUTS
class TalksController < ApplicationController
helper_method :talks, :talk, :tags
private
def talks
scope = Talk.published.includes(:event).order('events.finished_at desc')
@talks ||= params[:tag] ? scope.tagged_with(params[:tag]) : scope
@talks.page(params[:page]).per(12)
end
end
class PagesController < ApplicationController
helper_method :page
def show
page ? render(:show) : not_found
end
private
def page
@page ||= Page.find_by(url: params[:page_url])
end
end
class AuthController < ActionController::Base
layout "devise"
end

doctype html
html
head
title
= content_for?(:title) ? yield(:title) : t('default_title')
= stylesheet_link_tag 'app/application'
meta name="theme-color" content="#ffffff"
== render 'layouts/ga/head'
body class="#{yield(:main_body_class)}"
= yield(:before_header)
== render 'layouts/app/flash'
== render 'layouts/app/header'
main
= yield
52
application.slim vs admin.slim
doctype html
html
head
title
= content_for?(:title) ? yield(:title) : t('default_admin_title')
= stylesheet_link_tag 'admin/application'
meta name="viewport" content="width=device-width,
initial-scale=1, shrink-to-fit=no"
body
.ui.sidebar.inverted.vertical.menu
== render 'layouts/admin/navigation'
.pusher
.ui.container#container
== render 'layouts/admin/header'
= yield
== render 'layouts/admin/footer'

views/events/index.slim
...
tbody
- events.each do |event|
tr
th = event.id
td = resource_link(event)
td = format_timestamp(event.started_at)
td = format_timestamp(event.finished_at)
53
HELPERS
helpers/...
module TalksHelper
def talk_link(talk, text = "", options = {})
link_to text, polymorphic_path(talk), options
end
end
module ApplicationHelper
def format_timestamp(timestamp, time: true, delimiter: '-')
return unless timestamp
formatted_date = timestamp.strftime('%Y %b %d')
formatted_time = timestamp.strftime('%H:%M')
return formatted_date if !time
"#{formatted_date} #{delimiter} #{formatted_time}"
end

● Fat model and Skinny controller
● Business logic should always be in the
model
● The view should have minimal code
● Use helpers!
● Use models
● DRY (Don't Repeat Yourself)
54
BEST
PRACTICES

https://github.com/rails/rails
http://api.rubyonrails.org/
http://guides.rubyonrails.org/
https://github.com/bbatsov/rails-style-guide
55
RESOURCES

Rails MVC by Sergiy Koshovyi

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