为什么在symfony 3.4中呈现php模板是打印http标头？

Question

I'm trying to move from a messy PHP template structure, with many duplicated code, to slots to help us having a similar twig philosophy with the extends.

The problem that we have is that some templates are rendering the HTTP Headers:

The code for Form/form.html.php is:

<?php
/**
 * @var \Symfony\Bundle\FrameworkBundle\Templating\TimedPhpEngine    $view
 * @var \Symfony\Bundle\FrameworkBundle\Templating\Helper\FormHelper $formHelper
 * @var \Symfony\Component\Templating\Helper\SlotsHelper             $slotsHelper
 * @var \Symfony\Component\Form\FormView                             $form
 */
$formHelper = $view['form'];
$slotsHelper = $view['slots'];

?>
<div class="form-wrapper">
    <?php $slotsHelper->output('form-start', $formHelper->start($form)) ?>
    <?php $slotsHelper->output('form-widget', $formHelper->widget($form)) ?>
    <?php $slotsHelper->output('form-end', $formHelper->end($form)) ?>
</div>

And the code for the other template, Form/Order/form.html.php, is

<?php
/**
 * @var \Symfony\Bundle\FrameworkBundle\Templating\TimedPhpEngine    $view
 * @var \Symfony\Bundle\FrameworkBundle\Templating\Helper\FormHelper $formHelper
 * @var \Symfony\Component\Templating\Helper\SlotsHelper             $slotsHelper
 * @var \Symfony\Component\Form\FormView                             $form
 */
$formHelper = $view['form'];
$slotsHelper = $view['slots'];
$view->extend(':Form:form.html.php');

$slotsHelper->start('form-widget');
echo $formHelper->widget($form);
$slotsHelper->stop();

In the Controller, I'm rendering the form as always I've rendered a form:

$this->render("Form/Order/form.html.php", ['form' => $orderForm->createView()])

If I change this sentence by "returned string", Symfony prints only this "returned string", not the headers.

The form is rendered correctly, but for some reason that I cannot understand, Symfony is printing the HTTP Headers.

Thanks!

Answer 1

Well, after asking I still researching about it and I finally found out why and thanks to this article.

I've executed render, but render returns the rendered template as Response, therefore the HTTP Headers. renderView just return the template rendered.

So I've just had to change the line:

$this->render("Form/Order/form.html.php", ['form' => $orderForm->createView()])

to

$this->renderView("Form/Order/form.html.php", ['form' => $orderForm->createView()])

Now, it works as expected.