php 如何获取一维标量数组作为学说dql查询结果？
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How to get a one-dimensional scalar array as a doctrine dql query result?
提问by Dawid Ohia
I want to get an array of values from the id column of the Auction table. If this was a raw SQL I would write:
我想从 Auction 表的 id 列中获取一组值。如果这是一个原始 SQL，我会写：
SELECT id FROM auction
But when I do this in Doctrine and execute:
但是当我在 Doctrine 中执行此操作并执行时：
$em->createQuery("SELECT a.id FROM Auction a")->getScalarResult();
I get an array like this:
我得到一个这样的数组：
array(
array('id' => 1),
array('id' => 2),
)
Instead, i'd like to get an array like this:
相反，我想得到一个这样的数组：
array(
1,
2
)
How can I do that using Doctrine?
我如何使用 Doctrine 做到这一点？
回答by Lionel Gaillard
PHP < 5.5
PHP < 5.5
You can use array_map, and since you only have on item per array, you can elegantly use
'current'as callback, instead of writing a closure.
您可以使用array_map, 并且由于每个数组只有一个 item ，因此您可以优雅地
'current'用作回调，而不是编写闭包。
$result = $em->createQuery("SELECT a.id FROM Auction a")->getScalarResult();
$ids = array_map('current', $result);
See Petr Sobotka's answer belowfor additional info regarding memory usage.
有关内存使用情况的其他信息，请参阅下面的 Petr Sobotka 的回答。
PHP >= 5.5
PHP >= 5.5
As jcbwlkr's answered below, the recommended way it to use array_column.
正如jcbwlkr 在下面回答的那样，推荐使用array_column.
回答by jcbwlkr
As of PHP 5.5 you can use array_columnto solve this
从 PHP 5.5 开始，您可以使用array_column来解决这个问题
$result = $em->createQuery("SELECT a.id FROM Auction a")->getScalarResult();
$ids = array_column($result, "id");
回答by Ioan Badila
A better solution is to use PDO:FETCH_COLUMN. To do so you need a custom hydrator:
更好的解决方案是使用PDO:FETCH_COLUMN. 为此，您需要一个定制的水化器：
//MyProject/Hydrators/ColumnHydrator.php
namespace DoctrineExtensions\Hydrators\Mysql;
use Doctrine\ORM\Internal\Hydration\AbstractHydrator, PDO;
class ColumnHydrator extends AbstractHydrator
{
protected function hydrateAllData()
{
return $this->_stmt->fetchAll(PDO::FETCH_COLUMN);
}
}
Add it to Doctrine:
将其添加到 Doctrine：
$em->getConfiguration()->addCustomHydrationMode('COLUMN_HYDRATOR', 'MyProject\Hydrators\ColumnHydrator');
And you can use it like this:
你可以像这样使用它：
$em->createQuery("SELECT a.id FROM Auction a")->getResult("COLUMN_HYDRATOR");
更多信息：http: //docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/dql-doctrine-query-language.html#custom-hydration-modes
回答by Petr Sobotka
Ascarius' answer is elegant, but beware of memory usage! array_map()creates a copy of passed array and effectively doubles memory usage. If you work with hundreds of thousands of array items this can become an issue. Since PHP 5.4 call-time pass by reference has been removed so you cannot do
Ascarius 的回答很优雅，但要注意内存使用！array_map()创建传递数组的副本并有效地将内存使用量加倍。如果您使用数十万个数组项，这可能会成为一个问题。由于 PHP 5.4 call-time pass by reference 已被删除，所以你不能这样做
// note the ampersand
$ids = array_map('current', &$result);
In that case you can go with obvious
在这种情况下，您可以使用明显的
$ids = array();
foreach($result as $item) {
$ids[] = $item['id'];
}
回答by Minras
I think it's impossible in Doctrine. Just transform result array into the data structure you want using PHP:
我认为在 Doctrine 中这是不可能的。只需使用 PHP 将结果数组转换为您想要的数据结构：
$transform = function($item) {
return $item['id'];
};
$result = array_map($transform, $em->createQuery("SELECT a.id FROM Auction a")->getScalarResult());
