Rails 5ネストされたリソースHas-Many Throughアソシエーションを使用したURL

Question

Has-Many Through Associationメソッドを使用して小さなテストアプリケーションを作成しましたが、ネストされたルート内でlink_toを使用するように見えます。

エラーメッセージ

No route matches {:action=>"show", :controller=>"categories", :location_id=>#<Category id: 1, name: "parties", created_at: "2017-11-01 17:40:25", updated_at: "2017-11-01 17:40:25">}, missing required keys: [:id] 

location.rb

class Location < ApplicationRecord 
    belongs_to :product 
    belongs_to :category 
end 

category.rb

class Category < ApplicationRecord 
    has_many :locations 
    has_many :products, through: :locations 
end 

product.rb

class Product < ApplicationRecord 
    has_many :locations 
    has_many :categories, through: :locations 
end 

routes.rbを

Rails.application.routes.draw do 
    resources :locations do 
    resources :categories do 
     resources :products 
    end 
    end 
    root :to => 'locations#index' 
end 

カテゴリ/ index.htmlを

... 
<% @categories.each do |category| %> 
    <tr> 
    <td><%= category.name %></td> 
    <td><%= link_to 'Show', location_category_path(category) %></td> 
    <td><%= link_to 'Edit', edit_location_category_path(category) %></td> 
    <td><%= link_to 'Destroy', location_categories_path(category), method: :delete, data: { confirm: 'Are you sure?' } %></td> 
    </tr> 
<% end %> 
... 

127.0.0.1:3000/rails/info/routes

location_category_products_path GET /locations/:location_id/categories/:category_id/products(.:format) 
products#index 

POST /locations/:location_id/categories/:category_id/products(.:format) 
products#create 

new_location_category_product_path GET /locations/:location_id/categories/:category_id/products/new(.:format) 
products#new 

edit_location_category_product_path GET /locations/:location_id/categories/:category_id/products/:id/edit(.:format) 
products#edit 

location_category_product_path GET /locations/:location_id/categories/:category_id/products/:id(.:format) 
products#show 

PATCH /locations/:location_id/categories/:category_id/products/:id(.:format) 
products#update 

PUT /locations/:location_id/categories/:category_id/products/:id(.:format) 
products#update 

DELETE /locations/:location_id/categories/:category_id/products/:id(.:format) 
products#destroy 

location_categories_path GET /locations/:location_id/categories(.:format)  
categories#index 

POST /locations/:location_id/categories(.:format)  
categories#create 

new_location_category_path GET /locations/:location_id/categories/new(.:format)  
categories#new 

edit_location_category_path GET /locations/:location_id/categories/:id/edit(.:format) 
categories#edit 

location_category_path GET /locations/:location_id/categories/:id(.:format)  
categories#show 

PATCH /locations/:location_id/categories/:id(.:format)  
categories#update 

PUT /locations/:location_id/categories/:id(.:format)  
categories#update 

DELETE /locations/:location_id/categories/:id(.:format)  
categories#destroy 

locations_path GET /locations(.:format)  
locations#index 

POST /locations(.:format)  
locations#create 

new_location_path GET /locations/new(.:format)  
locations#new 

edit_location_path GET /locations/:id/edit(.:format) 
locations#edit 

location_path GET /locations/:id(.:format)  
locations#show 

PATCH /locations/:id(.:format)  
locations#update 

PUT /locations/:id(.:format)  
locations#update 

DELETE /locations/:id(.:format)  
locations#destroy 

root_path GET/ 
locations#index 

Answer 1

：ちょうどアルスラーン」の答えに追加する

<!-- /locations/:location_id/categories/:id --> 
<%= link_to 'Show', [{location_id}, {category_id}] %> 

Answer 2

location_category_path GET /locations/:location_id/categories/:id(.:format)  

あなたがここに見ることができるように、ルート：location_category_path必要な2つのこと：:location_id & :id（あなたが参照したいカテゴリのid）。

あなたのケースでは、あなたは1つしか指定しておらず、他のユーザーは指定していません。 :location_idも指定する必要があります。

[location_id, category_id]という短いURLがあります。 location_idで始まる両方のIDを持つ配列を書くだけです。

ルートの

Answer 3

：あなたはいくつかのこと、ロケーションIDオブジェクトとカテゴリIDのオブジェクトが必要

location_category_path GET /locations/:location_id/categories/:id(.:format)  

。

まだコントローラがない場合は、コントローラに@locationを設定する必要があります。

アプリ/コントローラ/ categories_controller.rb

class CategoriesController < ApplicationController 
    def index 
    @location = # your code here 
    end 
end 

アプリ/ビュー/カテゴリ/ index.htmlを。ルートのURLパラメータのERB

<% @categories.each do |category| %> 
    <tr> 
    <td><%= category.name %></td> 
    <td><%= link_to 'Show', location_category_path(@location.id, category.id) %></td> 
    <td><%= link_to 'Edit', edit_location_category_path(@location.id, category.id) %></td> 
    <td><%= link_to 'Destroy', location_categories_path(@location.id, category.id), method: :delete, data: { confirm: 'Are you sure?' } %></td> 
    </tr> 
<% end %> 

、いずれかを使用でき：あなたのルートの順序（:location_id、その後:idである）あなたがbundle exec rake routesを行うとき、またはあなたがすることもできるが、以下の

location_category_path(@location.id, category.id) 

location_category_path(location_id: @location.id, id: category.id)