Question

我想在tag / show.html.erb中获取下面的多对多关系表（Tag-Service-Category）中的数据。

class Tag < ActiveRecord::Base
    has_many :service_tags
    has_many :services, through: :service_tags
end

class ServiceTag < ActiveRecord::Base
    belongs_to :service
    belongs_to :tag
end
class Service < ActiveRecord::Base
    has_many :service_tags
    has_many :tags, through: :service_tags
    has_many :service_categories
    has_many :categories, through: :service_categories
end
class ServiceCategory < ActiveRecord::Base
    belongs_to :service
    belongs_to :category
end
class Category < ActiveRecord::Base
    has_many :service_categories
    has_many :services, through: :service_categories
end

我写了这样的代码，但它没有用。 @tag = Tag.find（params [：id]）

<% @tag.services.each do |service| %>
 <% service.categories.each do |category| %>
        <span class="category" class="<%= category.id %>"><%= category.name %></span>
        <% end %>
<% end %>

控制器/ tags_controller.rb

class TagsController < ApplicationController
    def show
        @tag = Tag.find(params[:id])
        @tags = Tag.all
    end
end

Answer 1

虽然您的数据库关系正确，但您仍然需要调用连接模型。因为您要做多对多的关系，所以您需要创建一个中间数组。尝试将此添加到您的视图中：

<% services_array = [] %>
<% @tag.service_tags each do |service_tag| %>
  <% services_array << service_tag.service %>
<% end %>
<% services_array.each do |service| %>
  <span class="category">
    <%= service.service_category.category.id %>
    <%= service.service_category.category.name %>
  </span>
<% end %>

我想从多个表格

1 个答案: