如何定义一个named_scope来汇总一个具有嵌套模型的has_many?
首先是数据模型:
class Forum < ActiveRecord::Base
has_many :topics, :dependent => :destroy, :order => 'created_at desc'
end
class User < ActiveRecord::Base
has_many :topics, :dependent => :destroy
has_many :comments, :dependent => :destroy
has_many :replies, :dependent => :destroy
end
class Topic < ActiveRecord::Base
belongs_to :forum
belongs_to :user
has_many :comments, :dependent => :destroy
end
class Comment < ActiveRecord::Base
belongs_to :user
belongs_to :topic
has_many :replies, :dependent => :destroy
end
class Reply < ActiveRecord::Base
belongs_to :user
belongs_to :comment
end
因此用户可以将主题发布到论坛。他们还可以将评论发布到 论坛中的主题。他们可以发布对评论的回复。
我希望能够获得他们参加过的论坛列表 发布主题或评论或回复。
First the data model:
class Forum < ActiveRecord::Base
has_many :topics, :dependent => :destroy, :order => 'created_at desc'
end
class User < ActiveRecord::Base
has_many :topics, :dependent => :destroy
has_many :comments, :dependent => :destroy
has_many :replies, :dependent => :destroy
end
class Topic < ActiveRecord::Base
belongs_to :forum
belongs_to :user
has_many :comments, :dependent => :destroy
end
class Comment < ActiveRecord::Base
belongs_to :user
belongs_to :topic
has_many :replies, :dependent => :destroy
end
class Reply < ActiveRecord::Base
belongs_to :user
belongs_to :comment
end
So Users can post Topics to Forums. They can also post Comments to the
Topics in a Forum. And they can post Replies to the Comments.
I want to be able to get a list of Forums they've participated in by
posting either Topics or Comments or Replies.
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您正在寻找的是论坛模型中的命名范围 。
通过在论坛模型中为 Comment 和 Reply 模型添加 has_many :through 关系,可以大大简化连接。但我永远不记得嵌套连接是如何工作的,所以我发布了一个可以与您所拥有的解决方案一起使用的解决方案。
现在...
将返回用户发布主题、回复或评论的论坛数组。
对于特定用户已发布的论坛列表:
假设我是对的,此语句:
将返回已按主题、评论或回复在论坛中发布的用户列表。
PS:在这个模型中允许破坏用户可能不是一个好主意。按照您安排的方式,如果用户被破坏,他们发布的任何主题、回复或评论也将被删除。相反,您的用户应该被停用。
What you're looking for is a named scope in the Forum model.
The join can be greatly simplified by adding has_many :through relationships for your Comment and Reply models in the Forum model. But I can never remember how nested joins work out, so I've posted a solution that will work with what you've got.
Now...
Will return an array of forums where a user has posted a topic, reply or comment.
For a list of forums a particular user has posted in:
Assuming I got that right, this statement:
will return a list of users that have posted in forum either by topic, comment or reply.
P.S. it's probably not a good idea to allow destruction of users in this model. The way you've laid things out, if a user is destroyed, any topics, replies or comments they posted will also be removed. Instead your users should be deactivated.