我可以使用“开"吗?DQL 中的关键字还是我需要使用 Native Query? [英] Can I use "ON" keyword in DQL or do I need to use Native Query?

问题描述

我在 Post 和 PostVote 之间有一个 oneToMany 关系.我希望能够检索帖子以及特定用户如何对其进行投票.在 DQL 中，我想检索 Post 和相关的 PostVote 实体，但只有一个 user_id 是例如 5.

I have a oneToMany relationship between Post and PostVote. I would like to be able to retrieve a Post and how a specific user voted on it. In DQL I would like to retrieve Post and related PostVote entity, but only one where user_id is for example 5.

我似乎无法像这样使用 ON sql 关键字:

I don't seem to be able to use ON sql keyword like this:

->createQuery('SELECT p, pv FROM Post p LEFT JOIN p.postvotes ON pv.user = :userid WHERE p.id = :postid')

如果我使用 WHERE 来过滤结果，就会产生问题并且不会显示结果，除非至少存在一个 postvote 对象:

And if I use WHERE to filter out results, it create a problem and does not display a result unless at least one postvote object exists:

->createQuery('SELECT p, pv FROM Post p LEFT JOIN p.postvotes WHERE p.id = :postid' AND pv.user = :userid)

本机查询是我实现这一目标的唯一方法吗?

Is Native Query the only way I can achieve this?

推荐答案

你必须在 DQL 中使用 WITH 关键字来完成这个:

You have to use the WITH keyword in DQL to accomplish this:

SELECT p, pv FROM Post p LEFT JOIN p.postvotes WITH pv.user = :userid WHERE p.id = :postid

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