导轨包括与选择 [英] rails include with options

问题描述

是否有可能限制一个AR：包括说只拉一个记录...

Is it possible to limit an AR :include to say only pull in one record...

Item.find(:all,
    :include => [ :external_ratings, :photos => LIMIT 1 ])

予有项目的列表和每个项目具有介于5和15的照片。我想加载照片的身份证到内存中，但我并不需要所有的人，我只是想preVIEW第一个。

I have a list of items and each item has between 5 and 15 photos. I want to load a photo id into memory, but i don't need all of them, I just want to preview the first one.

有没有办法做到这一点？

Is there a way to do this?

推荐答案

我不打算去调查详细的查询，但我想的find_by_sql 是为了针对这种特殊情况下。

I'm not going to investigate the detailed query, but I'm thinking find_by_sql is in order for this particular case.

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