Rails3通过问题嵌套has_many

发布于 2024-09-17 17:47:54 字数 431 浏览 5 评论 0原文

我们计划将我们的应用程序升级到 Rails3。我们经常使用的一个插件是nested_has_many_through。这个插件似乎已经过时，不再维护，并且似乎无法在新的 Rails3 应用程序中工作。

一个简单的例子：

Author.rb
has_many :posts
has_many :categories, :through => :posts, :uniq => true
has_many :related_posts, :through => :categories

Post.rb
belongs_to :author
belongs_to :category

Category.rb
has_many :posts

任何人都可以推荐处理这个问题的最佳实践方法，或者一个有效的 Rails3 插件吗？

谢谢！！

原文

We are planning to upgrade our application to Rails3. One plugin we've used quite a bit is nested_has_many_through. This plugin seems outdated, and no longer maintained, and simply does not appear to be working in a new Rails3 application.

A simple example:

Author.rb
has_many :posts
has_many :categories, :through => :posts, :uniq => true
has_many :related_posts, :through => :categories

Post.rb
belongs_to :author
belongs_to :category

Category.rb
has_many :posts

Can anyone recommend the best practice way to handle this, or a working Rails3 plugin?

Thanks!!

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滥情空心 2024-09-24 17:47:54

这是内置于 Rails 3.1 中的： http://asciicasts.com/episodes/265 -rails-3-1-概述

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给不了的爱 2024-09-24 17:47:54

我对 has_many :lated_posts 部分感到更困惑。您是否想将分类帖子本质上合并在一起？例如，“x”类别中的所有帖子都被视为“相关”？如果是这样，那么由于没有相关帖子类，这将不起作用，因此要至少解决此问题，您必须在关联上指定 :class_name ：

has_many :related_posts, :class_name => 'Post', :through => :categories

但其次，这可能不是正确的方法。由于任何作者都已经通过author_id外键发布了has_many帖子，因此尝试回溯类别表是没有意义的，而是使用分组逻辑。

清理这个问题的替代方法：

Author.rb

has_many :posts do
  def related
    all.group_by(&:category_id)
  end
end
author.posts.related
=> OrderedHash

当然，如果这不是您想要实现的目标，那么所有这些都是没有意义的。：P

I'm more confused by the has_many :related_posts part. Are you trying to essentially join together categorized posts? Like, all posts in 'x' category are considered 'related'? If so, this won't work based on there not being a RelatedPost class, so to fix this at a bare minimum, you'd have to specify :class_name on the association:

has_many :related_posts, :class_name => 'Post', :through => :categories

But secondly, it's probably not the correct approach to begin with. Since any author already has_many posts via the author_id foreign key, there is no sense in trying to weave back through the categories table, instead use grouping logic.

Alternate approaches that clean this up:

Author.rb

has_many :posts do
  def related
    all.group_by(&:category_id)
  end
end
author.posts.related
=> OrderedHash

Of course, all of this is moot if it wasn't what you were trying to accomplish. :P

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黄昏下泛黄的笔记 2024-09-24 17:47:54

Rails 3（未经测试，首先按最相关类别的帖子排序）：

category.rb：

class Category < ActiveRecord::Base
  class << self
    def posts
      Post.joins(:categories).
           where(:categories => select('id').all.map(&:id)).
           group('posts.id').
           order('count(*) DESC')
    end
  end
end

用法：

related_posts = author.categories.posts

Rails 3 (untested, orders by posts with most related categories first):

category.rb:

class Category < ActiveRecord::Base
  class << self
    def posts
      Post.joins(:categories).
           where(:categories => select('id').all.map(&:id)).
           group('posts.id').
           order('count(*) DESC')
    end
  end
end

Usage: