Rails的ActiveRecord的：是一个组合：包括和：条件查询的可能吗？ [英] Rails ActiveRecord: Is a combined :include and :conditions query possible?

问题描述

想象一下，我有维基文章，有许多修订。我想通过数据库，其中仅返回那些有它在过去24小时内被更新修订文章做ActiveRecord的查询。这样的事情可能吗？

Imagine I have wiki Articles, with many Revisions. I'd like to do a query with ActiveRecord through the database, which only returns those Articles which have Revisions which are updated in the past 24 hours. Is such a thing possible?

我想像它会是这样的：

Articles.find_all(:include => :revisions, 
                  :conditions => {:revision[updated_at] => 1.week.ago..Time.now.utc})

如果这是不可能的，是有一些类型的原始SQL中我可以传递到的find_by_sql是会做的伎俩？

If this isn't possible, is there some type of raw SQL I could pass to find_by_SQL that'd do the trick?

推荐答案

如果您只需要文章，并不需要所有的修改渴望加载，你可以使用：连接代替。它使用较少的内存，因为它不是preloading所有修订每篇文章。用途：包括但如果你会做这样的事情 article.revisions

If you only need the article and don't need eager loading of all the revisions, you could use :joins instead. It uses less memory because it's not preloading all the revisions for each article. Use :include though if you will be doing something like article.revisions.

Article.find(:all, 
  :joins => :revisions, 
  :conditions => ["revisions.updated_at > ?", 24.hours.ago]
)

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