Symfony 2 & Twig, how to access block from extension - symfony

Question

I'm creating my Twig Extension to extend the actual "FormExtension".
Reason for that is that I need to create new functions without overwriting the current ones and making this available across my entire project.
So building and extension seemed to be the right way to go.
Building the extension is not a problem, my problem is how to render block from there?
What I understood till here, is that I need to create a Twig_Environment where I have to load my actual twig template (containing my blocks).
From there I should be able to render those block using "$mytemplate->displayBlock()".
Sample code:
public function renderWidgetinline(FormView $view, array $variables = array())
{
$loader = new \Twig_Loader_Filesystem(__DIR__.'/../Resources/views/Form');
$twig = new \Twig_Environment($loader);
$this->template = $twig->loadTemplate("form_layout.html.twig");
ob_start();
$this->template->displayBlock(???WHAT-PARAMS???);
$html = ob_get_clean();
return $html;
}
I found those information by looking at the Symfony base FormExtension.php file.
My questions are:
How does displayBlock() works, where can I found the defintion of that function?
Is what I described above the right way to go?
How should I proceed to have access to that new TWIG template together with the base form_div_layout.html template? Can I somehow get the current environment without having to recreated one and load my additional template there?
Thanks!

Answer 1

Have you tried to use renderBlock instead?
The first parameter you need is the name of the block, and the second should be an associative array of values passed to the block.
So what you would have in the case of a service that is rendering a block is the following:
The Service Class:
<?php
namespace Acme\BlockBundle\Blocks;
use Doctrine\Common\Persistence\ObjectManager;
Class Block {
private $om;
private $environment;
private $template;
public function __construct( ObjectManager $om, Twig $environment )
{
$this->om = $om;
$this->environment = $environment;
}
public function render( $template, $data )
{
$this->template = $this->environment->loadTemplate( $template );
// maybe query the DB via doctrine, that is why I have included $om
// in the service arguments
// example:
$entities = $om->getRepository( 'AcmePizzaBundle:Pizza' )->getMeatyOnes()
return $this->template->renderBlock( 'acme_block', array(
'data' => $entities,
));
}
}
The Twig Extension Class
<?php
namespace Acme\BlockBundle\Twig\Extension;
use Twig_Extension;
use Twig_Function_Method;
class BlockExtension extends Twig_Extension
{
protected $container;
public function __construct( $container )
{
$this->container = $container;
}
public function getName()
{
return 'block_extension';
}
public function getFunctions()
{
return array(
'render_block' => new Twig_Function_Method( $this, 'renderBlock', array(
'is_safe' => array( 'html' ),
)),
);
}
public function renderBlock( $template, $data )
{
return $this->container->get( 'acme.block' )->render( $template, $data );
}
}
The services.yml
parameters:
acme.blocks.block.class: Acme\BlocksBundle\Blocks\Block
acme.twig.block_extension.class: Acme\BlocksBundle\Twig\Extension\BlockExtension
services:
acme.blocks.block:
class: '%acme.blocks.block.class%'
arguments:
- '#doctrine.orm.entity_manager'
- '#twig'
acme.twig.block_extension:
class: %acme.twig.block_extension.class%
arguments:
- '#service_container'
tags:
- { name: twig.extension }
don't forget your template:
{% block acme_block %}
{% spaceless %}
{# do something with your data here #}
{% endspaceless %}
{% endblock acme_block %}
Then when you want to display it, you just need to call the twig function you have just created:
{{ render_block( '::block_template.html.twig', someDataOneThePage ) }}
By no mean this is a complete solution, but I have used something similar and it proved to be working.
HTH
Tam
[edit: April 2016 - for reference: this solution was working on a Symfony 2.4 project]