自参照关联问题

Question

我有下面的模型：

create_table :categories do |t|
  t.integer :category_id
  t.integer :language_id
  t.timestamps
end

create_table :category_localizated_categories, :force => true do |t|
  t.column :category_id, :integer
  t.column :localizated_category_id, :integer
end

class Category < ActiveRecord::Base
  has_many :category_localizated_categories
  has_many :localizated_categories, :through => :category_localizated_categories
end

class CategoryLocalizatedCategory < ActiveRecord::Base
   belongs_to :category
   belongs_to :localizated_category
end

我可以这样做：

category1 = Category.create :language_id => 1
category2 = category1.localizated_categories.create :language_id => 2

在数据库中创建了两个类别，但没有创建关联：

category.localizated_categories
[]

可能的问题是什么？谢谢。

Answer 1

为什么你不去找一个更简单的自我参照的联想呢？

class Category < ActiveRecord::Base
  belongs_to :base_category, :class_name => "Category"
  has_many :localized_categories, :class_name => "Category", :inverse_of => :base_category

  scope :base, where(:base_category_id => nil)
  scope :localized, where("base_category_id NOT NULL")
  …
end

Answer 2

class Category < ActiveRecord::Base
  has_many :category_localizated_categories
  has_many :localizated_categories, :through => :category_localizated_categories
  accepts_nested_attributes_for :category_localizated_categories
end

我认为这里需要嵌套模型：

http://ryandaigle.com/articles/2009/2/1/what-s-new-in-edge-rails-nested-attributes