ruby-on-rails - 具有 join_table 和 has_many 的模型的路由错误 :through in RailsAdmin

Question

所以我有 3 个模型:category , product , category_products .

这是我的 category.rb

  attr_accessible :name
    has_many :category_products do
         def with_products
           includes(:product)
         end
       end

  has_many :products, :through => :category_products

这是我的 product.rb

  attr_accessible :name, :description, :price, :vendor_id, :image, :category_ids

    belongs_to :vendor
    has_many :category_products do
           def with_categories
             includes(:category)
           end
    end

    has_many :categories, :through => :category_products

这是我的 category_product.rb

  attr_accessible :product_id, :category_id, :purchases_count

    belongs_to :product
  belongs_to :category

  validates_uniqueness_of :product_id, :scope => :category_id

这是我的 routes.rb

  mount RailsAdmin::Engine => '/admin', :as => 'rails_admin'
  resources :categories
  resources :vendors do
      resources :products
  end

  authenticated :user do
    root :to => 'home#index'
  end

  root :to => "home#index"
  devise_for :users
  resources :users

当我点击 Categories当我查看 RailsAdmin 时，出现此错误:

ActionController::RoutingError at /admin/category

Message No route matches {:action=>"show", :model_name=>"category_product", :id=>nil, :controller=>"rails_admin/main"}

当我单击 Category Products 时，我也收到此错误消息

ActiveRecord::StatementInvalid at /admin/category_product

Message SQLite3::SQLException: no such column: category_products.desc: SELECT "category_products".* FROM "category_products" ORDER BY category_products. desc LIMIT 20 OFFSET 0

RailsAdmin 中用于我的其他“正常”(即非 HMT)模型的所有其他链接都有效。

什么可能导致这种情况？

谢谢。

编辑 1

值得一提的是，以下是我在 Rails Admin 中单击“类别”时的日志:

CodeRay::Scanners could not load plugin nil; falling back to :text
CodeRay::Scanners could not load plugin nil; falling back to :text


Started GET "/admin/category?_pjax=%5Bdata-pjax-container%5D" for 127.0.0.1 at 2012-12-20 22:23:38 -0500
Processing by RailsAdmin::MainController#index as HTML
  Parameters: {"_pjax"=>"[data-pjax-container]", "model_name"=>"category"}
  Category Load (0.3ms)  SELECT "categories".* FROM "categories" LIMIT 6
  User Load (0.2ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1
  Category Load (0.2ms)  SELECT "categories".* FROM "categories" ORDER BY categories.id desc LIMIT 20 OFFSET 0
  CategoryProduct Load (0.2ms)  SELECT "category_products".* FROM "category_products" WHERE "category_products"."category_id" = 2
  Rendered /.rvm/gems/ruby-1.9.3-p194@apt-605/gems/rails_admin-0.3.0/app/views/rails_admin/main/index.html.haml within layouts/rails_admin/pjax (29.4ms)
Completed 500 Internal Server Error in 43ms
CodeRay::Scanners could not load plugin nil; falling back to :text
CodeRay::Scanners could not load plugin nil; falling back to :text


Started GET "/admin/category" for 127.0.0.1 at 2012-12-20 22:23:40 -0500
Processing by RailsAdmin::MainController#index as HTML
  Parameters: {"model_name"=>"category"}
  Category Load (0.3ms)  SELECT "categories".* FROM "categories" LIMIT 6
  User Load (0.2ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1
  Category Load (0.2ms)  SELECT "categories".* FROM "categories" ORDER BY categories.id desc LIMIT 20 OFFSET 0
  CategoryProduct Load (0.2ms)  SELECT "category_products".* FROM "category_products" WHERE "category_products"."category_id" = 2
  Rendered /.rvm/gems/ruby-1.9.3-p194@apt-605/gems/rails_admin-0.3.0/app/views/rails_admin/main/index.html.haml within layouts/rails_admin/application (30.5ms)
Completed 500 Internal Server Error in 251ms

编辑 2

这是一个 gist of the full trace的错误。我正在使用 gem better_errors，所以跟踪看起来不像标准的 Rails 跟踪错误。但是数据是一样的。

编辑 3

这是我的 3 个模型的架构:
CategoryProducts

# == Schema Information
#
# Table name: category_products
#
#  product_id      :integer
#  category_id     :integer
#  purchases_count :integer          default(0)
#  created_at      :datetime         not null
#  updated_at      :datetime         not null

Category

# == Schema Information
#
# Table name: categories
#
#  id         :integer          not null, primary key
#  name       :string(255)
#  created_at :datetime         not null
#  updated_at :datetime         not null

Product

# == Schema Information
#
# Table name: products
#
#  id          :integer          not null, primary key
#  name        :string(255)
#  description :string(255)
#  price       :float
#  vendor_id   :integer
#  created_at  :datetime         not null
#  updated_at  :datetime         not null
#  image       :string(255)

请注意 CategoryProduct没有主键字段。是这个问题吗？

Answer 1

检查所有 CategoryProduct 对象是否有外键:category_id 和 product_id。

CategoryProduct.all.each {|c| raise("Repair #{c.id}") unless c.category && c.product}

12 月 21 日更新:

我如何使用 Category、Product 和 CategoryProduct 安装全新的 Rails 3.2.9。模型的关系代码是相同的，RailsAdmin 使用默认设置。

它没有任何问题!

我决定检验我的假设。我想也许当您从 HABTM 转到 HM2HM 时，您已经错过(忘记)重新建立 CategoryProduct 的键列 ID，它现在不仅仅是一个连接模型，而是一个独立的实体。

因此，路由错误如下:

No route matches {:action=>"show", :model_name=>"category_product", :id=>nil, :controller=>"rails_admin/main"}

可能是缺少 id 的结果。

好吧，我手动禁用了 CategoryProduct 的 id 字段(def id；nil；end)。

是的，它是:

No route matches {:action=>"show", :model_name=>"category_product", :id=>nil, :controller=>"rails_admin/main"}