如何在 Symfony 中将实体导出为 CSV？

我使用以下代码输出 CSV，但运行时出现空白屏幕。基本上我的困惑在于 DoctrineORMQuerySourceIterator 因为我不明白如何正确使用它。我假设我必须列出属性名称？？？

我正在使用索纳塔导出器：

https://github.com/sonata-project/exporter https://github.com/sonata-project/exporter

<?php

$repository = $this->getDoctrine()->getRepository('MainReferralCaptureBundle:Referral');
$referrals = $repository->createQueryBuilder('r')->select('r.pLastName, r.pFirstName')->getQuery();

// $referrals2 = $referrals->getResult();
// var_dump($referrals2);

$data = array(
    0 => array('name' => 'Jack'),
    1 => array('name' => 'Jill')
);

// Pick a format to export to
$format = 'csv';

// Filename
$filename = 'referral.csv';

// Set Content-Type
$content_type = 'text/csv';

// Location to Export this to
$export_to = 'php://output';

// Data to export
$exporter_source = new \Exporter\Source\DoctrineORMQuerySourceIterator($referrals, array('pLastName, pFirstName'));

// Get an Instance of the Writer
$exporter_writer = '\Exporter\Writer\\' . ucfirst($format) . 'Writer';

$exporter_writer = new $exporter_writer($export_to);

// Set the right headers
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Content-Description: File Transfer');
header('Content-type: ' . $content_type);
header('Content-Disposition: attachment; filename=' . $filename . ';');
header('Expires: 0');
header('Pragma: public');

// Export to the format
\Exporter\Handler::create($exporter_source, $exporter_writer)->export();

第二个参数DoctrineORMQuerySourceIterator是一个属性名称数组，如下所示：

['Column name in the output' => 'fieldName', 'Something' => 'address.street']

正如你在源代码 https://github.com/sonata-project/exporter/blob/458980410a11689b591a67dd083188d002a43b4c/lib/Exporter/Source/DoctrineORMQuerySourceIterator.php#L57它实际上使用属性存取器 http://symfony.com/doc/2.3/components/property_access/introduction.html组件来访问数据（您可以在那里找到更多示例）。

如果您想从数据库导出原始数据，我建议使用PDOStatementSourceIterator https://github.com/sonata-project/exporter/blob/458980410a11689b591a67dd083188d002a43b4c/lib/Exporter/Source/PDOStatementSourceIterator.php or the DoctrineDBALConnectionSourceIterator https://github.com/sonata-project/exporter/blob/458980410a11689b591a67dd083188d002a43b4c/lib/Exporter/Source/DoctrineDBALConnectionSourceIterator.php相反，因为它们更快。前者需要一个PDOStatement另一个需要一个连接、一个查询和一个参数数组（您可以在链接的源代码中看到它）作为构造函数参数。