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NestedRoutes Example

Directions

• Create a Rails project named NestedRoutes with two scaffold-based controllers with model names Pet and Owner. Include owner_id as one of the fields for Owner. For example, you could use these fields:
  

  Owner name:string phone:string
  Pet name:string animal_type:string owner_id:integer
  

• Set up a one-to-many relationship between Owner and Pet by adding
  

  has_many :pets
  

  in the Owner model and
  

  belongs_to :owner
  

  in the Pet model.
• Because every owner owns a collection of pets, the pets resource can be thought of as being nested inside the owners resource. To configure pets as a resource nested inside of owners, change the resource declarations in config/routes.rb from
  

  resources :owners
  resources :pets
  

  to
  

  resources :owners do
      resources :pets
  end
  

• After making this change, the owners are still accessed as before because they are not nested in any other resource.
   
• However, we should be able to access the pets according to their owners as shown in the Nested RESTful Routes Table. To show pet number 3 of owner 5, use this URL:
  

  http://localhost:3000/owners/5/pets/3
  

• After making the change in the routes file, we need to modify the Pets controller so that it functions correctly. The rest of this document describes the changes that must be made for pets to function as a nested resource within owners.
  
  1. Get the owner id from the route
     
     1. Enter this code at the bottom of the controller after the private get_pet method:
        

        def get_owner
          @owner = Owner.find(params[:owner_id])
        end
        

     2. Invoke the get_owner method at the beginning of the controller before the before_filter :set_pet statement:

        before_filter :get_owner
        

  2. Update the view routes.
      
     In the Pet views (index, show, new, edit), replace the scaffold-generated named routes in the first table by the named nested routes in the second table.
  3. Update the find statements in the Pets controller.   Because the pets are nested within owners, we don't want all pets; we want only the pets that belong to the owner with id=owner_id.
     
     1. In the index method, replace
        

        @pets = Pet.all
        

        by
        

        @pets = @owner.pets
        

     2. In the private set_pet method at the bottom of the controller, replace
        

        @pet = Pet.find(params[:id])
        

        by
        

        @pet = @owner.pets.find(params[:id])
        

        
        
     3. In the new method, replace
        

        @pet = Pet.new
        

        by
        

        @pet = @owner.pets.build 
        

     4. In the create method, replace
        

        @pet = Pet.new(params[:pet])
        

        by
        

        @pet = @owner.pets.build(pet_params) 
        

         
• Update the form_for statement
   
  In _form.html.erb, replace the @pet object in the form_for statement by the array [@owner, @pet].
• Update the redirect URLs in the controller.   In the Pet controller, replace the scaffold-generated named routes in the first table by the named nested routes in the second table.
• Localhost URL to view the owners index view:
  

  http://localhost:3000/owners