Rails 多个所属的分配 [英] Rails multiple belongs_to assignment

问题描述

给定

用户:

class User < ActiveRecord::Base
   has_many :discussions
   has_many :posts
end

讨论:

class Discussion < ActiveRecord::Base
    belongs_to :user
    has_many :posts
end

帖子:

class Post < ActiveRecord::Base
    belongs_to :user
    belongs_to :discussion 
end

我目前正在通过

@post = current_user.posts.build(params[:post])

我的问题是，如何设置/保存/编辑@post 模型，以便同时设置帖子和讨论之间的关系?

My question is, how do I set/save/edit the @post model such that the relationship between the post and the discussion is also set?

推荐答案

保存和编辑讨论以及帖子

现有讨论

要将您正在构建的帖子与现有讨论相关联，只需将 id 合并到帖子参数中

To associate the post you're building with an existing discussion, just merge the id into the post params

@post = current_user.posts.build(
          params[:post].merge(
            :discussion_id => existing_discussion.id
        ) 

您必须在 @post 的表单中为讨论 id 设置一个隐藏输入，以便保存关联.

You will have to have a hidden input for discussion id in the form for @post so the association gets saved.

新讨论

如果您想与每个帖子一起构建新讨论并通过表单管理其属性，请使用 accepts_nested_attributes

If you want to build a new discussion along with every post and manage its attributes via the form, use accepts_nested_attributes

class Post < ActiveRecord::Base
  belongs_to :user
  belongs_to :discussion
  accepts_nested_attributes_for :discussion
end

您必须在构建帖子后使用 build_discussion 在控制器中构建讨论

You then have to build the discussion in the controller with build_discussion after you built the post

@post.build_discussion

并且在您的表单中，您可以包含用于讨论的嵌套字段

And in your form, you can include nested fields for discussions

form_for @post do |f|
  f.fields_for :discussion do |df|
    ...etc

这将与帖子一起创建讨论.有关嵌套属性的更多信息，观看这个精彩的 railscast

此外，您可以使用 has_many 关联，以获得更一致的关系设置:

Furthermore, you can use the :through option of the has_many association for a more consistent relational setup:

class User < ActiveRecord::Base
  has_many :posts
  has_many :discussions, :through => :posts, :source => :discussion
end

class Discussion < ActiveRecord::Base
  has_many :posts
end

class Post < ActiveRecord::Base
  belongs_to :user
  belongs_to :discussion 
end

这样，用户与讨论的关系只在Post模型中维护，而不是在两个地方.

Like this, the relation of the user to the discussion is maintained only in the Post model, and not in two places.

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