Symfony2 自定义表单渲染器辅助函数

Question

I want to define a new twig function "form_field" which renders form_label , form_widget and form_errors . I don't want to override form_row because I already did that for a different purpose: form_row also wraps <div/> container required for my layout. Specifically, I add bootstrap classes.

Why do I need this? Normally I use form_row but I have lots of form rows for which I want to place two ore more fields in the same line (eg "first name" and "last name"). In those cases I define my wrapping <div/> manually, but I don't want to write the three function calls ( form_label , form_widget and form_errors ) everytime.

I tried to specify a custom function, but I get an exception when calling the twig functions there. For this solution I need to know, how to call Twig functions from a custom function.

My second attempt was to adapt Symfony's solution for its own form helpers. I found this line in vendor/symfony/symfony/src/Symfony/Bridge/Twig/Extension/FormExtension.php:

new \Twig_SimpleFunction('form_widget', null, array('node_class' => 'Symfony\Bridge\Twig\Node\SearchAndRenderBlockNode', 'is_safe' => array('html'))),

Looks like a function which actually just renders a block. When I adapted that line in my AppBundle, an exception was thrown in which Symfony claimed that a block named "form_field" is undefined. However, I defined this block in my custom form template:

{% use 'bootstrap_3_horizontal_layout.html.twig' %}

{%- block form_field -%}
    {{- form_label(form) -}}
    {{- form_widget(form) -}}
    {{- form_errors(form) -}}
{%- endblock form_field -%}

Answer 1

Declare a twig template Form/form_field.html.twig:

{%- block form_field -%}
    {{- form_label(form, label) -}}
    {{- form_widget(form) -}}
    {{- form_errors(form) -}}
{%- endblock form_field -%}

Then I used the renderBlock method in my Twig custom function. This is my twig extension file as described here :

namespace AppBundle\Twig;

class AppExtension extends \Twig_Extension
{
    protected $environment;
    private $template;

    public function __construct(\Twig_Environment $env)
    {
        $this->environment = $env;
    }


    public function getFunctions()
    {
        return array(
            'form_field' => new \Twig_SimpleFunction('form_field', array($this, 'formField'), array(
                'is_safe' => array('html')
            ))
        );
    }

    public function formField($form, $label = null)
    {
        $this->template = $this->environment->loadTemplate( '::Form/form_field.html.twig' );

        return $this->template->renderBlock('form_field', array(
            'form' => $form,
            'label' => $label
        ));
    }

    /**
     * Returns the name of the extension.
     *
     * @return string The extension name
     */
    public function getName()
    {
        return 'app_extension';
    }
}

I configured the DI container to pass the Twig_Environment for the AppExtension service:

services:
    app.twig_extension:
        class: AppBundle\Twig\AppExtension
        arguments:
            - '@twig'
        tags:
            - { name: twig.extension }