检索中给定用户评论的所有帖子，Ruby on Rails的 [英] Retrieve all posts where the given user has commented, Ruby on Rails

问题描述

我的用户，文章和评论。用户可以发布只有一个评论，以每个岗位。

I have users, posts and comments. User can post only one comment to each post.

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

class Post < ActiveRecord::Base
  has_many :comments
  belongs_to :user
end

class Comment < ActiveRecord::Base
  belongs_to :user
  belongs_to :post
end

在userpage（的http：//主机/用户/ 1 为例）我想说明中给定用户评论所有文章。然后，每个职位将所有其他意见。

On userpage (http://host/users/1 for example) I want to show all posts where the given user has commented. Each post then will have all other comments.

我可以做这样的事情在我的用户控制器：

I can do something like this in my User controller:

def show
  @user = User.find(params[:user_id])
  @posts = []
  user.comments.each {|comment| @posts << comment.post}
end

这样，我会找到用户，那么他所有的意见，那么相应的后每个注释，然后（在我看来），每篇文章我将呈现post.comments。我在Rails的全新的，这样我就可以做到这一点=），但我认为这是莫名其妙地坏的，有一个更好的方式来做到这一点，也许我应该使用范围或named_scopes（还不知道这是什么，但看起来可怕的）。

This way I will find User, then all his comments, then corresponding post to each comment, and then (in my view) for each post I will render post.comments. I'm totally new in Rails, so I can do this =) But I think it's somehow bad and there is a better way to do this, maybe I should use scopes or named_scopes (don't know yet what this is, but looks scary).

所以，你点我出到正确的方向吗？

So can you point me out to the right direction here?

在此先感谢您的帮助。

伊利亚

推荐答案

您可以定义哪些检索所有在单个查询意见职位的关联。保持它在模型降低你的控制器的复杂性，使您能够重复使用的关联，并且更容易进行单元测试。

You could define an association which retrieves all the posts with comments in a single query. Keeping it in the model reduces the complexity of your controllers, enables you to reuse the association and makes it easier to unit test.

class User < ActiveRecord::Base
  has_many :posts_with_comments, :through => :comments, :source => :post
  # ...
end

：通过是的has_many 一个选项来指定一个连接表，通过它来进行查询。我们需要指定：源和Rails就无法推断来源：post_with_comments 。

:through is an option for has_many to specify a join table through which to perform the query. We need to specify the :source as Rails wouldn't be able to infer the source from :post_with_comments.

最后，更新您的控制器使用的关联。

Lastly, update your controller to use the association.

def show
  @user  = User.find(params[:user_id])
  @posts = @user.posts_with_comments
end

要了解更多关于：通过和：源看看的<一个href="http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html#method-i-has_many"相对=nofollow>文档。

To understand more about :through and :source take a look at the documentation.

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