Question

如何告知has_many :through和/或foreign_key使用哪个class关联？

我已尝试过上述的每一种排列，通常会收到：NoMethodError: undefined method 'relation_delegate_class' for "User":String

ActiveRecord::Schema.define(version: 20141031013511) do

 create_table "messages", force: true do |t|
    t.string   "content"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.integer  "creator_id"
  end

  create_table "messages_views", force: true do |t|
    t.integer "message_viewed"
    t.integer "message_viewer"
  end

  create_table "shows_viewers", force: true do |t|
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  create_table "users", force: true do |t|
    t.string   "username"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

end

class MessagesView < ActiveRecord::Base
  belongs_to :message_viewed
  belongs_to :message_viewer
end

class Message < ActiveRecord::Base
  belongs_to :creator, class_name: 'User'
  has_many :messages_views
  has_many :message_viewers, through: :messages_views, class: 'User', foreign_key: 'message_viewer'
end

class User < ActiveRecord::Base
  has_many :messages, foreign_key: 'creator_id'
  has_many :messages_views
  has_many :message_vieweds, through: :messages_views, class: 'Message', foreign_key: 'message_viewed'
end

This是该应用的当前状态。

Answer 1

我认为关联表和你的代码的问题应该是这样的：

class MessagesView < ActiveRecord::Base
  belongs_to :message_viewed, class_name: 'Message'
  belongs_to :message_viewer, class_name: 'User'
end

class Message < ActiveRecord::Base
  belongs_to :creator, class_name: 'User'
  has_many :messages_views, foreign_key: 'message_viewed', class_name: "messages_view"
  has_many :message_viewers, through: :messages_views, class_name: 'User', foreign_key: 'message_viewer'
end

class User < ActiveRecord::Base
  has_many :messages, foreign_key: 'creator_id'
  has_many :messages_views, foreign_key: 'message_viewer', class_name: "messages_view"
  has_many :message_vieweds, through: :messages_views, class_name: 'Message', foreign_key: 'message_viewed'
end

使用has_many：through时如何指定foreign_key和class？

1 个答案: