在嵌套属性的情况下验证连接表

Question

我有一个 rails4 应用程序，但我刚刚意识到我忘记通过查找没有 product_id 的 db 对象向我的 IndustryProducts 表添加验证。

用户可以在接受nested_attributes 的产品表单中创建product，以便通过collection_select 选择一个或多个industries。到目前为止一切正常，但是当我尝试将IndustryProducts 表中的presence 验证添加到外键字段（product_id 和industry_id）时，我在选择一个或多个行业后提交表单时收到错误消息：Industry products product can not be blank 和 Industry products is invalid。如果我什么都不选，那么我当然会收到至少选择一个的消息。

我错过了什么？如何验证product_id 和industry_id 都存在于IndustryProducts 表中？

class Product < ActiveRecord::Base
  has_many :industry_products, dependent: :destroy
  has_many :industries, through: :industry_products

  accepts_nested_attributes_for :industry_products, reject_if: :all_blank, allow_destroy: true

  validates_associated :industry_products
end

class Industry < ActiveRecord::Base
  has_many :industry_products
  has_many :products, through: :industry_products

  #accepts_nested_attributes_for :industry_products #THIS LINE MAKES NO DIFFERENCE; tried with and without it

  validates :name, presence: { messsage: "can not be blank" }
end


class IndustryProduct < ActiveRecord::Base
  belongs_to :product
  belongs_to :industry
  #accepts_nested_attributes_for :industry #THIS LINE NEITHER MAKES DIFF; tried with and without it


  #IF I PUT THESE LINES IN THEN I GET THE ERRORS I MENTIONED ABOVE    
  validates :product, presence: { message: "can not be blank" }
  validates :industry, presence: { message: "can not be blank" }
end

产品形式：

<%= form_for @product,....
  <%= f.collection_select :industry_ids, Industry.all.order(name: :asc), :id, :name, {}, { multiple: true, class: "form-control" } %>
.....

产品的strong_params：

params.require(:product).permit( :name,  industry_ids: [], .....)       

通过 POST 请求发送的参数：

"product"=>{"name"=>"asdfasfasdfqqqq", "industry_ids"=>["4", "8"], "description"=>"", .........}

控制器

def new
  @product = Product.new
  @product.industry_products.build
end

def create
  @product = current_user.products.new(product_params)
  if @product.save
  ......
end

Answer 1

我必须像这样在产品模型中添加inverse_of: :product，现在一切正常：

class Product < ActiveRecord::Base
  has_many :industry_products, dependent: :destroy, inverse_of: :product
  .......