Symfony 2: pass custom variable to twig form template - php

Question

In just started at symfony and Im trying to do something very simple (seems simple to me) using the form templating system, but I cant find a way to do it.
My goal is to render a "back" button besides the submit button. I know how to set the form template and how to override the submit_widget, but the problem is: the back button URL must be defined at the template which is calling the form, so I need to pass this as a variable to the submit_widget somehow, and I cant find a way to do it.
Ideally, it would work like this:
Template:
{% form_theme form 'TutsAdminBundle:Form:bootstrap-horizontal.html.twig' %}
{% block content %}
<h1>User creation</h1>
{{ form(form, { 'attr': {'role': 'form', 'class': 'form-horizontal'}, 'back': path('list_user') }) }}
{% endblock %}
And then, at the form template
{% block submit_widget %}
<div class="col-sm-6 col-sm-offset-1">
<div class="pull-right">
<a class="btn btn-warning" href="{{ back }}"> Back</a>
<button type="submit" class="btn btn-success">Save</button>
</div>
</div>
{% endblock submit_widget %}
But I just cant find a way to access my "back" variable inside the submit_widget block.
How can I achieve that?
UPDATE:
I managed to do what I wanted by:
1- creating a custom field following Chausser advice bellow:
class SaveButtonType extends SubmitType
{
public function __construct($router)
{
$this->_router = $router;
}//constructor
protected $_router;
/* (non-PHPdoc)
* #see \Symfony\Component\Form\AbstractType::buildForm()
*/
public function buildForm(FormBuilderInterface $builder, array $options)
{
}//buildForm
public function setDefaultOptions(OptionsResolverInterface $resolver)
{
$href = function(Options $options, $value){
return array('href'=>$this->_router->generate($options['route'], $options['params']), 'class'=>'btm btn-warning');
};
$resolver->setDefaults(array('mapped'=>false))->setRequired(array('route', 'params'));
$resolver->setNormalizers(array('attr'=>$href));
}//setDefaultOptions
public function getName()
{
return 'save_button';
}//getName
}//SaveButtonType
Ive made it extends the SubmitType otherwise it would be rendered inside a form_row.
services.yml
tuts_admin.form.field.type.save_button:
class: Tuts\AdminBundle\Form\Field\SaveButtonType
arguments: ["#router"]
tags:
- {name: "form.type", alias: "save_button"}
2- then I defined its template (on that same file Im using to override the form theme
{% block save_button_widget %}
<div class="col-sm-6 col-sm-offset-1">
<div class="pull-right marginL25">
<button type="submit" class="btn btn-success">Save</button>
</div>
<div class="pull-right">
Back
</div>
</div>
{% endblock %}
This type render the submit and the back button at once.
3- finally, since I could not find a way to prevent the rendering of another submit button, I overrided the submit_widget:
{% block submit_widget %}
{% endblock submit_widget %}
A lot more complicated than I was expecting, but it does works.
Thank you Chausser for all your help.

Answer 1

Personally I would write a Custom Field Type and make if for back buttons. Something that will accept a route name and route params.
//Acme/DemoBundle/Form/Type/BackButtonType
<?php
namespace Acme\DemoBundle\Form\Type;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;
use Symfony\Component\OptionsResolver\Options;
class BackButtonType extends AbstractType
{
protected $router;
public function __construct($router)
{
$this->router = $router;
}
public function setDefaultOptions(OptionsResolverInterface $resolver)
{
$attr = function(Options $options, $value){
return array(
'href'=>$this->_router->generate($options['route'], $options['params']),
'class'=>'btn btn-warning'
);
};
$resolver
->setDefaults(array(
'attr' => $attr,
'mapped' => false
'params' => array(),
))
->setRequired(array(
'route',
))
->setNormalizers(array(
'attr'=>$attr
));
}
public function getName()
{
return 'back_button';
}
}
Then you need to register this as a new form type:
parameters:
acme_demo.form.type.back_button.class: Acme\DemoBundle\Form\Type\BackButtonType
services:
acme_demo.form.type.back_button:
class: %acme_demo.form.type.back_button.class%
arguments: ["#router"]
tags:
- { name: "form.type", alias: "back_button" }
Now you can use this in your normal forms. Last step is to create the twig block to render this form.
//Acme/DemoBundle/Resources/Twig/fields.html.twig
{% block back_button_widget %}
<a {{block('widget_attributes')}}>{{block('form_label')}}</a>
{% endblock %}
Then you need to add this file to the form resources for twig:
//app/config/config.yml
twig:
debug: %kernel.debug%
strict_variables: %kernel.debug%
form:
resources:
- 'AcmeDemoBunlde:Twig:fields.html.twig'
After you have done that you need to clear your caches:
php app/console cache:clear --env=dev
php app/console cache:clear --env=prod
Now how to use this:
//In your Form
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
// Add other fields
->add('back', 'back_button',array('route'=>'my_custom_route_name','params'=>array('user_id'=>$this->getUser()->getUserId())))
->add('submit','submit',array('attr'=>array('class'=>'btn btn-primary')));
}
This should work. Hasnt been fully tested but if you have any issues with it let me know.

Answer 2

I believe that you don't need to pass variable, but only make it available (known) to Twig, since form rendering (as opposed to to extending and including other templates) is just block rendering. That is, those variables are in the same scope.
So:
Parent template
{% set back = "MyFooValue" %}
Form template:
<div class="{{ back }}">Some content</div>
Also, I like defining default as fallback in case I forget to (or do not at all) define variable:
<div class="{{ back|default("") }}">Some content</div>
Hope this helps...