为什么Doctrine QueryBuilder会破坏我的查询？ [英] Why does Doctrine QueryBuilder destroy my query?

问题描述

我正在尝试在表格中收到最新的 id 。因此，我创建了一个静态类，以便从任何所需的表中获取最新的 id 。

I am trying to receive the latest id in a table. Therefore I created a static class to be able to fetch this latest id from any desired table.

public static function getLatestId($entityManager, $table, $column) {
    $qb = $entityManager->createQueryBuilder();
    $qb->select('t.'.$column)->from($table, 't')
       ->orderBy('t.'.$column, 'DESC')->setMaxResults(1);
    $query = $qb->getQuery();
    $result = $query->getSingleResult();
    $latestId = $result[$column];
    return $latestId;
}

当我调用函数例如使用 getLatestId（$ em，'company'，'companyId'）并检查查询（使用 getQuery（）它创建了奇怪的声明：

When I call the function e.g. with getLatestId($em, 'company', 'companyId') and check the query (with getQuery(), it creates weird statement:

SELECT c0_.companyId AS companyId0 FROM company c0_
ORDER BY c0_.companyId DESC LIMIT 1

为什么要将 t。 c0 _。，后缀为<？c $ c> 0 到列？

Why does it replace the t. by c0_. and suffixes a 0 to the column?

推荐答案

首先你要检索一个部分，默认情况下会返回一个标量变量，所以为了清楚起见，使用getSingleScalarResult（）方法是很好的参见： http://docs.doctrine-project.org/en/latest/reference/partial-objects。 html

First you are retreiving a partial, which will return a scalar variable by default. So for clarity it's good to use the getSingleScalarResult() method. See also: http://docs.doctrine-project.org/en/latest/reference/partial-objects.html

然后你试图读取userId列，但是你传递了companyId列，所以替换这个：

Then you are trying to read the userId column, but you passed the companyId column. So replace this:

$latestId = $result['userId'];

与此：

$latestId = $result[$column];

不要担心别名给你的列的别名。这是正常的行为，它有助于Doctrine在内部映射一切正确的方式。

Don't worry about the aliases Doctrine gives to your columns. This is normal behaviour and it helps Doctrine to map everything the right way internally.

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