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我将如何处理包含以下内容的belong_to。而不是显示 product_colour_id id，而是显示关联的颜色（更新：解决了下面的这部分）。product_colour_id 位于 Product 表中，并与相应的 Product_colour id 匹配。

这是我无法解决的两个或多个 has_many 关联的情况。可以做到吗？

应用程序/控制器/home_controller.rb

  class HomeController < ApplicationController
  def index
    products = Product.last(5)
    product_ids = products.map(&:id)   
    @product_colour_ids = products.map(&:product_colour_id)
    @allproduct_colours = ProductColour.all 
    @product_colour_map = ProductColour.find(@product_colour_ids)   
    @product_images = Product.includes(:product_images)
                    .where(product_images: {product_id: product_ids, :default_image => true})
  end
end

/app/views/home/index.html.erb

<% @product_images.each do |pd| %>
          <%= content_tag :div, :class => "col-md-3 col-sm-6 hero-feature" do %>
          <% pd.product_images.each do |i| %>
              <div class="thumbnail">
                <%= image_tag (i.product_image(:medium)) %>
          <% end %> </div>
          <div class="caption">
            <h3><%= pd.product_name %></h3>
            <p><%= pd.product_description %></p>
            <p> <%= pd.product_colour_id %></p>
          </div>
          <% end %>
      <% end %>
    </div>

我很难找到多个 has_many 包含的示例。我认为它有一个非常直接的模式，但无法从apidock或api.rubyonrails.org 解决。我遇到的问题是将 Supply_company 添加为 has_many :through 关系到我已经与 product_image 包含的关系。

预先感谢您的建议

更新我已经弄清楚如何显示belongs_to ...感觉有点愚蠢，因为它很容易只是需要一些时间思考

 <% pd.product_images.each do |pd| %>
   <p> <%= pd.product_colour.product_colour %></p>
 <% end %>

/app/models/product.rb

class Product < ActiveRecord::Base
  belongs_to :product_type
  belongs_to :product_category
  belongs_to :product_colour
  belongs_to :product_size

  has_many :product_supply_companies, :foreign_key => 'product_id'
  accepts_nested_attributes_for :product_supply_companies, :allow_destroy => true
  has_many :supply_companies, :through => :product_supply_companies
  accepts_nested_attributes_for :supply_companies

  has_many :product_images, dependent: :destroy, :foreign_key => 'product_id'
  accepts_nested_attributes_for :product_images, :allow_destroy => true
end

应用程序/模型/product_supply_company.rb

class ProductSupplyCompany < ActiveRecord::Base
  belongs_to :product
  belongs_to :supply_company

 # accepts_nested_attributes_for :supply_company
 # accepts_nested_attributes_for :product

end

应用程序/模型/supply_company.rb

class SupplyCompany < ActiveRecord::Base

  has_many :products, :through => :product_supply_companies
  has_many :product_supply_companies, :foreign_key => 'supply_company_id'

  accepts_nested_attributes_for :products
  accepts_nested_attributes_for :product_supply_companies, :allow_destroy => true

end

应用程序/模型/product_colour.rb

class ProductColour < ActiveRecord::Base
  has_many :products
end

数据库模式

 create_table "product_categories", force: true do |t|
    t.string   "product_category"
    t.string   "product_category_description"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  create_table "product_colours", force: true do |t|
    t.string   "product_colour"
    t.string   "product_colour_description"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  create_table "product_images", force: true do |t|
    t.integer  "product_id",                 null: false
    t.datetime "created_at",                 null: false
    t.datetime "updated_at",                 null: false
    t.string   "product_image_file_name"
    t.string   "product_image_content_type"
    t.integer  "product_image_file_size"
    t.datetime "product_image_updated_at"
    t.boolean  "default_image"
  end

  create_table "product_sizes", force: true do |t|
    t.string   "product_size"
    t.string   "product_size_description"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  create_table "product_supply_companies", force: true do |t|
    t.integer  "product_id"
    t.integer  "supply_company_id"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  create_table "product_types", force: true do |t|
    t.string   "product_type"
    t.string   "product_type_description"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  create_table "products", force: true do |t|
    t.string   "product_name"
    t.text     "product_description"
    t.integer  "product_type_id"
    t.integer  "product_category_id"
    t.string   "product_colour_id"
    t.integer  "product_size_id"
    t.datetime "created_at"
    t.datetime "updated_at"
  end
4

2 回答 2

1 
@products = Product.includes(:product_images, :colour, :supply_companies)
                   .where(product_images: {product_id: product_ids, :default_image => true})
                   .select('products.*, product_colours.product_colour')

这是具有所有关联的查询。

index.html.erb

<% @products.each do |pd| %>
    <%= content_tag :div, :class => "col-md-3 col-sm-6 hero-feature" do %>
    <% pd.product_images.each do |i| %>
        <div class="thumbnail">
          <%= image_tag (i.product_image(:medium)) %>
        </div>
    <% end %> 
    <div class="caption">
      <h3><%= pd.product_name %></h3>
      <p><%= pd.product_description %></p>
      <p><%= pd.product_colour %></p>
    </div>
    <% end %>
<% end %>

产品.rb

belongs_to :colour, class: 'ProductColor', foreign_key: 'product_colour_id'
于 2015-06-03T10:49:08.353 回答
0

对于后面的人。User123 给了我一些想法，最终提供了解决方案。我一直在思考这个问题。

应用程序/控制器/home_controller.rb

class HomeController < ApplicationController
  def index
    products = Product.last(5)   ## find last five products 
    product_ids = products.map(&:id) ## map their ids so I can retrieve
    images with matching id's

    ## create array of products with corresponding default_images.
    ## Not necessary to include has_many, has_many :through or 
    ## belongs_to as they can be added directly on index.html.erb page

    @products = Product.includes(:product_images)
                    .where(product_images: {product_id: product_ids, :default_image => true}).last(5)

  end
end

/app/views/home/index.html.erb

  <% @products.each do |pd| #1st level directly access product_attributes %>
      <%= content_tag :div, :class => "col-md-3 col-sm-6 hero-feature" do %>

           <% pd.product_images.each do |i| # 2nd access has_many with
             foreign key in different table %>
              <div class="thumbnail">
                <%= image_tag (i.product_image(:medium)) %>
              </div>
          <% end %>

            <div class="caption">
            <h3><%= pd.product_name %></h3>
            <p><%= pd.product_description %></p>
            <p><%= pd.product_colour.product_colour #first level access 
                   belong_to relationship attributes %></p>

            <p><% pd.supply_companies.each do |sc| # 2nd level again to
                     access has_many :through relationship only done again for 
                     layout purposes. %></p>
                  <%= sc.company_name %>
            <% end %>
          </div>
      <% end %>
  <% end %>
于 2015-06-03T11:45:51.440 回答