原则2：水合键值数组 [英] Doctrine 2: Hydrate key-value array

问题描述

为什么该查询不起作用？

Why this query doesn't work?

    $query = $this->_em->createQuery('
        SELECT 
            COUNT(p) AS products_count
        FROM 
            Application\Entity\Category c
            INDEX BY c.id
            LEFT JOIN c.products p
        GROUP BY
            c.id
    ');

    $rows = $query->getSingleScalarResult();

我希望得到的结果为： category_id => products_count数组，但是会抛出一个学说\ORM\NonUniqueResultException，没有任何消息。

I expected to get the result as: "category_id => products_count" array, but it throws an Doctrine\ORM\NonUniqueResultException without any message.

推荐答案

如果您 COUNT 查询中 GROUPED 的行，它将返回多个结果以及每个组的计数。对于您来说，您将获得每个类别的计数。

If you COUNT the rows in a query that is GROUPED, it will return multiple results with the count for each group. In your case, you will get the counts for each Category.

如果尝试 getSingleScalarResult（）对具有多个条目的结果，将产生 Doctrine\ORM\NonUniqueResultException 。相反，您应该使用 getScalarResult（）并遍历条目。

If you try to getSingleScalarResult() on a result which has more than one entries, it will produce a Doctrine\ORM\NonUniqueResultException. Instead, you should use getScalarResult() and iterate through the entries.

编辑：

要将结果转换为 array（ category_id => products_count_value）的形式，可以使用以下代码：

To transform the results to the form array("category_id" => "products_count_value"), you can use the following code:

$output = array();
foreach ($rows as $category, $values) {
    $output[$category] = $values['products_count'];
}

$ output 应该现在包含您想要的值。

$output should now contain the values the way you want them.

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