Ruby on Rails-Rails Routing from the Outside In

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   Based on guides.rubyonrails.org

Rails Routing from the Outside In

    The Purpose of the Rails Router
        Simple example:
                                GET /patients/17
                    Route
                                get '/patients/:id', to: 'patients#show'

        Or
                    get '/patients/:id', to: 'patients#show', as: 'patient'
                    and your application contains this code in the controller:
                                @patient = Patient.find(17)
                    and this in the corresponding view:
                                <%= link_to 'Patient Record', patient_path(@patient) %>
                    Route will generate
                                /patients/17
        CRUD, Verbs, and Actions
            If declare
                resources :photos
                If creates 7 routes
                    HTTP        Verb             Path
                    GET        /photos             index  
                    GET        /photos/new      new
                    POST           /photos         create 
                    GET        /photos/:id         show  
                    GET        /photos/:id/edit edit     
                    PATCH/PUT  /photos/:id      update
                    DELETE     /photos/:id      destroy
            Singular resources
                To call
                    /profile
                route
                    get 'profile', to: 'users#show'

    A singular resourceful route generates these helpers:
        new_photo_path returns / photo /new
        edit_ photo _path returns / photo /edit
        photo _path returns / photo
        Controller Namespaces and routing
            It is possible to organize groups of controllers under a namespace
            EX:
            namespace : admin do
                            resources :posts, :comments
            end
            It will create routes for post and comments .  For Admin::PostController
                GET /admin/posts              admin_post_path
                GET /admin/posts/new         new_admin_post_path
                POST /admin/posts/:id       admin_post_path(:id)
                etc
            Uses Admin::PostController without the prefix /admin, just declares:
                scope module: ‘admin’ do
                    resources :posts, :comments   
                end
                OR
                resources :posts, module:’admin’

            To use /admin/post without  admin in path.
                Scope ‘/admin’ do
                                Resources :posts, :comments
                End
            Resources :posts, path: ‘/admin/posts’
                GET /admin/posts                           posts_path
                GET /admin/posts/new                                new_post_path
                Nested Resources
    when there are resources that are children of others.
        Models:
            class Magazine < ActiveRecord::Base
                  has_many
                    :ads
                end
             end
            class Ad < ActiveRecord::Base
                  belongs_to :magazine
            end
            Resources:
                resources :magazines do
                      resources :ads
                end
            /magazines/:magazine_id/ads
            /magazines/:magazine_id/ads/new
            /magazines/:magazine_id/ads
            The url: edit_magazine_ad_path
            It is possible to nest 2 levels
   
        resources :publishers do
          resources :magazines do
            resources :photos
          end
        end
        Calling:
            /publishers/1/magazines/2/photos/3
    Paths and URLs From Objects
        resources :magazines do
          resources :ads
        end
        You can pass instances of magazines and ads
            <%= link_to 'Ad details', magazine_ad_path(@magazine, @ad) %>
        Or
            <%= link_to 'Ad details', url_for([@magazine, @ad]) %>
            Or
            <%= link_to 'Ad details', [@magazine, @ad] %>
            Rails will se magazines and ads and create the path.
        To call Edit
        <%= link_to 'Edit Ad', [:edit, @magazine, @ad] %>
    Adding More RESTful Actions
        Add Member Routes
            resources :photos do
              member do
                get 'preview'
              end
            end
            Provides:   
            GET     /photos/1/preview
            and preview_photo_url and preview_photo_path helpers