ruby-on-rails - 帮助 HABTM :through

Question

到目前为止，我当前的 HABTM 实现与 :has_and_belongs_to_many 一起工作。 Notification 和 Privacy 都继承自 Preference。偏好是 STI。我想尝试使用 :has_many, :through 关联。

模型文件

class User < ActiveRecord::Base
  has_and_belongs_to_many :preferences
end

class Preference < ActiveRecord::Base
  has_and_belongs_to_many :users
end

class Notification < Preference
end

class Privacy < Preference
end

迁移文件

class UsersHaveAndBelongToManyPreferences < ActiveRecord::Migration
  def self.up
    create_table :preferences_users, :id => false do |t|
      t.references :preference, :user

      t.timestamps
    end
  end

  def self.down
    drop_table :preferences_users
  end
end

class CreatePreferences < ActiveRecord::Migration
  def self.up
    create_table :preferences do |t|
      t.string :title
      t.text :description
      t.string :type

      t.timestamps
    end
  end

  def self.down
    drop_table :preferences
  end
end

class DeviseCreateUsers < ActiveRecord::Migration
  def self.up
    create_table(:users) do |t|
      t.string :name
      t.timestamps
    end
  end

  def self.down
    drop_table :users
  end
end

我尝试了以下

class User < ActiveRecord::Base
  has_many :preferences, :through => :preferences_users
end

class Preference < ActiveRecord::Base
  has_many :users, :through => :preferences_users
end

我的表格看起来像

  <% Preference.where(:type => 'Notification').all.each do |notification| %>
    <li>
      <%= check_box_tag 'user[preference_ids][]', notification.id, @user.preference_ids.blank? ? false : @user.preferences.include?(notification) %>
      <%= label_tag notification.description %>
    </li>
  <% end %>

我明白了

Could not find the association :preferences_users in model User

我做错了什么？问题出在我的表格还是我的联想？

Answer 1

好的，它开始工作了。我需要一个模型 PreferencesUser，但在用户和偏好模型上缺少 has_many :preferences_users:

class PreferencesUser < ActiveRecord::Base
    belongs_to :user
    belongs_to :preference
end

class User < ActiveRecord::Base
  has_many :preferences_users
  has_many :preferences, :through => :preferences_users
end

class Preference < ActiveRecord::Base
  has_many :preferences_users
  has_many :users, :through => :preferences_users
end

不必更改我的表单中的任何内容。希望这对某人有帮助