Rails 4 has_many through - 消息发送者和接收者

Question

我正在尝试实现以下，关系和对象调用

一个用户可以发送许多消息（user.sent_messages） 一条消息可以有一个发件人（message.sender）

一个用户可以接收许多消息（user.received_messages） 一条消息可以有多个接收者（message.receivers）

我的架构如下所示：

create_table "activities", force: true do |t|
 t.integer  "sender_id"
 t.integer  "message_id"
 t.datetime "created_at"
 t.datetime "updated_at"
 t.integer  "receiver_id"
end

create_table "messages", force: true do |t|
 t.text     "body"
 t.datetime "created_at"
 t.datetime "updated_at"
 t.boolean  "read",       default: false
end

我的模型如下所示：

class User < ActiveRecord::Base
 has_many :activities, class_name: 'Activity', foreign_key: 'sender_id', dependent: :destroy
 has_many :sent_messages, through: :activities

 has_many :reverse_activities, class_name: 'Activity', foreign_key: 'receiver_id'
 has_many :received_messages, through: :reverse_activities
end

class Activity < ActiveRecord::Base
belongs_to :sent_messages, class_name: 'User'
belongs_to :received_messages, class_name: 'User'
belongs_to :message
end

class Message < ActiveRecord::Base
 has_many :activities, foreign_key: 'sender_id'
 has_one :sender, through: :activities, foreign_key: 'sender_id', class_name: 'User'

 has_many :reverse_activities, foreign_key: 'receiver_id', class_name: 'User'
 has_many :receivers, through: :reverse_activities, source: :receiver

end

sent_messages 和 received_messages 方法有效，但是它们直接指向 User 表并返回该用户的详细信息，而不是消息。

我还没有尝试让消息模型工作，因为用户模型不正确。

谢谢！

---

感谢这两个建议，我已经完成了以下工作

class User < ActiveRecord::Base

 has_many :activities, class_name: 'Activity', foreign_key: 'sender_id'
 has_many :sent_messages, through: :activities, foreign_key: 'message_id', class_name:     'Message', source: :sender

 has_many :reverse_activities, class_name: 'Activity', foreign_key: 'receiver_id'
 has_many :received_messages, through: :reverse_activities, foreign_key: 'message_id', class_name: 'Message', source: :receiver
end

class Message < ActiveRecord::Base
has_one :sent_activities, class_name: 'Activity', foreign_key: 'message_id'
has_one :sender, through: :sent_activities, foreign_key: 'sender_id', class_name: 'User'

has_many :receiver_activities, class_name: 'Activity', foreign_key: 'message_id'
has_many :receivers, through: :receiver_activities, foreign_key: 'receiver_id', class_name: 'User'

validates :body, presence: true
end

class Activity < ActiveRecord::Base
belongs_to :sender, class_name: 'User'
belongs_to :receiver, class_name: 'User'
belongs_to :receiver, class_name: 'Message'
belongs_to :sender, class_name: 'Message'
end

因此，我想要的方法有效。

现在只是为了让创建操作生效！

Answer 1

太复杂了

你为什么不试试这个：

#app/models/message.rb
Class Message < ActiveRecord::Base
    belongs_to :sender, class_name: "User", primary_key: "sender_id"
    belongs_to :recipient, class_name: "User", primary_key: "recipient_id"
end

#app/models/user.rb
Class User < ActiveRecord::Base
    has_many :sent_messages, class_name: "Message", foreign_key: "sender_id"
    has_many :received_messages, class_name: "Message", foreign_key: "recipient_id"
end

users
id | name | email | created_at | updated_at

messages
id | sender_id | recipient_id | title | body | created_at | updated_at

这将允许您像这样加载数据：

@message.sender
@message.recipient 

@user.sent_messages
@user.received_messages

要保存数据，您可以使用：

#app/controllers/messages_controller.rb
def new
    @message = Message.new
end

def create
    @message = Message.new(message_params)
end

private

def message_params
    params.require(:message).permit(:recipient_id, :title, :body).merge(sender_id: current_user.id)
end

#app/views/messages/new.html.erb (user has to be logged in)
<%= form_for @message do |f| %>
    <%= f.collection_select(:recipient_id, User.all, :id, :name) %>
    <%= f.text_field :title %>
    <%= f.text_area :body %>
    <%= f.submit %>
<% end %>

Answer 2

Model Message中有一些错误：

class Message < ActiveRecord::Base

foreign_key 不应该是：“message_id”吗？

 has_many :activities, foreign_key: 'sender_id'

foreign_key 中的同样问题：'sender_id'，以及其他可能的问题

 has_one :sender, through: :activities, foreign_key: 'sender_id', class_name: 'User'

 has_many :reverse_activities, foreign_key: 'receiver_id', class_name: 'User'
 has_many :receivers, through: :reverse_activities, source: :receiver

end

您好像使用消息的 id 来加入其他表的发送者 ID 和接收 ID。

class Activity < ActiveRecord::Base

类名为'User'，所以send_messages、received_messages返回用户信息

belongs_to :sent_messages, class_name: 'User'
belongs_to :received_messages, class_name: 'User'
belongs_to :message
end

希望对您有所帮助。