Question

我有这些联想：

character.rb

has_many :messagechats, dependent: :destroy
has_many :messageconversations, through: :messagechats, source: :conversation

messagechat.rb

belongs_to :character
belongs_to :conversation, class_name: 'Messageconversation', foreign_key: 'conversation_id'

messageconversation.rb

has_many :chats, class_name: 'Messagechat', dependent: :destroy
has_many :characters, through: :chats, source: :character

数据库中的Messagechat模型确实有conversation_id列，而不是messageconversation_id列。

我正在尝试将character添加到@messageconversation，其中包含：

@messageconversation.characters << character

但是这会引发这个错误：

ActiveModel::UnknownAttributeError (unknown attribute 'messageconversation_id' for Messagechat.)

因为<<假定联接模型中的foreign_key将来自messageconversation（即messageconversation_id）。我需要foreign_key为conversation_id。使用foreign_key设置<<的正确语法是什么？还是有另一种方法可以做到这一点吗？

Answer 1

首先，我认为你应该修改你的文件和类名来表示空格，即message_conversation.rb和class MessageConversation/:message_conversation。

您应该能够指定定义关联的外键。请参阅foreign_key options的导轨指南。

更新：我用您的模型制作了一个新的应用程序，希望它有助于说明。

class MessageChat < ApplicationRecord
  belongs_to :character
  belongs_to :conversation, class_name: 'MessageConversation'
end

class MessageConversation < ApplicationRecord
  has_many :chats,
           class_name: 'MessageChat',
           dependent: :destroy,
           foreign_key: :conversation_id
  has_many :characters, through: :chats
end

class Character < ApplicationRecord
  has_many :message_chats, dependent: :destroy
  has_many :message_conversations, through: :message_chats, source: :conversation
end

这有你正在寻找的所有协会（据我所知）工作。

irb(main):002:0> conversation = MessageConversation.create
=> #<MessageConversation id: 5>
irb(main):003:0> character = Character.create
=> #<Character id: 5>
irb(main):004:0> conversation.characters << character
=> #<ActiveRecord::Associations::CollectionProxy [#<Character id: 5>]>
irb(main):005:0> character.message_chats
=> #<ActiveRecord::Associations::CollectionProxy [#<MessageChat id: 2, character_id: 5, conversation_id: 5>]>

Rails - has_many through：添加到集合时设置连接模型外键？

1 个答案: