轨道不同表3合并多个查询 [英] rails 3 merge multiple queries from different tables

问题描述

我在我的控制器下面的查询。有没有办法，我可以将它们合并成一个什么办法？

  @record_videos = RecordVideo.where（支持建议=？，真）.limit（8）
@的音乐= Music.limit（13）
@ new_topics = Topic.limit（5）.order（created_at降序）
 

解决方案

没有，你不能将返回不同的类对象的多个查询。那么，你的可以的，从理论上讲，如果你写自己的查询的SQL，并使用了一些 UNION S，但Rails的很可能不知道该怎么做的结果数据。我不能，随便，想用例，其中这将是一个好主意。

现在，您可以轻松地查询的结果结合起来，你的Ruby code事后 - 如果，例如，你想他们都整理在一起，你可以这样做：

  @all_items = [@ record_videos.all，@ musics.all，@ new_topics.all] .flatten.sort_by {|事情| thing.created_at}
 

i have the following queries in my controller. Is there any way that i can merge them into one?

@record_videos = RecordVideo.where("recommand = ?",true).limit(8)
@musics=Music.limit(13)
@new_topics=Topic.limit(5).order("created_at desc")

解决方案

No, you cannot combine multiple queries that return different classes of object. Well, you could, theoretically, if you wrote your own query SQL and used a few UNIONs, but Rails would likely have no idea what to do with the resulting data. I can't, offhand, think of a use-case where this would be a good idea.

Now, you can easily combine the results of the queries after the fact in your Ruby code - if, for instance, you wanted to sort them all together, you could do this:

@all_items = [@record_videos.all, @musics.all, @new_topics.all].flatten.sort_by{ |thing|   thing.created_at}

这篇关于轨道不同表3合并多个查询的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！