使用嵌套属性的Rails中的多对多关系下拉菜单 [英] Drop-Down-Menu for Many-to-Many relation in rails using nested attributes

问题描述

我通过多对多关联拥有三个表:超市，产品和供应. 每个超市可以容纳许多产品，并且每种产品可以在许多超市中出售.关联是通过供应模型建立的.

I have three tables via many-to-many-association: Supermarket, Product and Supply. Each Supermarket can hold many products and each product can be sold in many supermarkets. The association is build via the Supply-model.

超市:

class Supermarket < ActiveRecord::Base
  attr_accessible :name, :address, :products_attributes

  has_many :supplies
  has_many :products, :through => :supplies

  accepts_nested_attributes_for :products
end

产品:

class Product < ActiveRecord::Base
  attr_accessible :name, :supermarkets_attributes

  has_many :supplies
  has_many :supermarkets, :through => :supplies
  accepts_nested_attributes_for :supermarkets
end

通过供应关联:

class Supply < ActiveRecord::Base
  attr_accessible :supermarket_id, :product_id

  belongs_to :supermarket
  belongs_to :product
end

我已经创建了脚手架，并填充了Supermarket-table. 在我的产品表单中，我想使用一个(或多个)下拉菜单来选择相应的超级市场名称.目标是在创建新产品的同时，还要通过供应表创建关联. 如果我要从那里选择相应的超市，代码的形式和/或控制器外观应该是什么样的?

I have created the scaffolds and populated the Supermarket-table. In my Product form, i want to use one (or more) drop-down-menu(s) to select the correspondent Supermarket-name(s). Goal is to create a new product while also creating the association via the Supply-table. What should the code look like in form and/or controller for the products if I want to select the corresponding supermarkets from there?

推荐答案

在您的产品表单中，您需要添加此行...

In you products form you need to add this line...

<%= collection_select(:product, :supermarket_ids, SuperMarket.all, :id, :name, {}, { :multiple => true } )%>

您也不必为此使用accepts_nested_attributes，您已经建立的多对多关联应处理其余的事情.

You also shouldn't need to use an accepts_nested_attributes for this, the many to many association you already have set up should take care of the rest.

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