Rails4 模型在“创建”操作时忽略 parent_id

Question

我有属于类别的子类别。我的应用程序在 id = 1 的子类别下保存（构建）我的所有子类别，即使我的代码似乎没问题并且不应该这样做：

子类别控制器：

    def create
      @category = Category.find_by(params[:id])
      @subcategory = @category.subcategories.build(subcategory_params)
      if @subcategory.save
        flash[:success] = "added subcategory"
        redirect_to admin_categories_url
      else
        render :new
      end
    end

...

    private

      def subcategory_params
        params.require(:subcategory).permit(:name, :category_id)
      end  

子类别.rb

class Subcategory < ActiveRecord::Base
  belongs_to :category
  has_many :products

  validates :name, presence: true
  validates :category_id, presence: true
end

表格：

<h3>Add a subcategory</h3>

<%= form_for [@category, @subcategory] do |f| %>
  <%= f.text_field :name, placeholder: "Name" %>
  <%= f.submit "Add a subcategory" %>
<% end %>

路由器：

resources :categories do
    resources :subcategories
  end

网址：

向 id = 3 的类别添加新的子类别

http://localhost:3000/categories/3/subcategories/new

日志：

Started POST "/categories/1/subcategories" for 127.0.0.1 at 2014-04-16 16:04:47 +0400
Processing by SubcategoriesController#create as HTML
  Parameters: {"utf8"=>"✓", authenticity_token"=>"74U3VyAN6NqEjhkuHGNHnPda/yzpc+dIcn2xBJ6Zi2A=", "subcategory"=>{"name"=>"A name"}, "commit"=>"Add subcategory", "category_id"=>"1"}
  User Load (0.2ms)  SELECT  "users".* FROM "users"  WHERE "users"."id" = $1 LIMIT 1  [["id", 1]]
  Category Load (0.2ms)  SELECT  "categories".* FROM "categories"  WHERE "categories"."id" = $1 LIMIT 1  [["id", 1]]
   (0.1ms)  BEGIN
  SQL (0.2ms)  INSERT INTO "subcategories" ("category_id", "created_at", "name", "updated_at") VALUES ($1, $2, $3, $4) RETURNING "id"  [["category_id", 1], ["created_at", "2014-04-16 12:04:47.151729"], ["name", "A name"], ["updated_at", "2014-04-16 12:04:47.151729"]]
   (0.8ms)  COMMIT

ID 为 1

这可能是什么问题？

更新

做的时候

@category = Category.find_by(params[:category_id])

出现此错误：

ERROR:  argument of WHERE must be type boolean, not type integer
LINE 1: SELECT  "categories".* FROM "categories"  WHERE (1) LIMIT 1

如果这样做

@category = Category.find(params[:category_id])

问题存在

Answer 1

在您的 create 操作中，您选择的是子类别的 ID，而不是类别。将其更改为：

def create
  @category = Category.find(params[:category_id])
  ...

也需要在new 方法中对设置@category 进行相同的更改，以便category_id 在视图的参数中返回为3。当然，这种复制也可以使用控制器中的辅助方法进行干燥。

要查看 id 的差异，您可以使用rake routes，您应该会看到如下内容：

new_category_subcategory   GET   /categories/:category_id/subcategories/new   subcategories#new

这表明它需要参数 category_id 作为类别 ID。

Answer 2

看看你的参数是category_id而不是id

 Parameters: {"utf8"=>"✓", authenticity_token"=>"74U3VyAN6NqEjhkuHGNHnPda/yzpc+dIcn2xBJ6Zi2A=", "subcategory"=>{"name"=>"A name"}, "commit"=>"Add subcategory", "category_id"=>"1"}

#=> "category_id"=>"1"

   Category.find_by(category_id: params[:category_id]) 

所以你需要这样做

 def create
  @category = Category.find_by(category_id: params[:category_id])
  @subcategory = @category.subcategories.build(subcategory_params)
  if @subcategory.save
    flash[:success] = "added subcategory"
    redirect_to admin_categories_url
  else
    render :new
  end
end