覆盖Symfony2表单主题时，变量“ form”不存在

Question

I am having an issue all of the sudden where I am getting the following error on my Symfony2 site: Variable "form" does not exist in SiteBackendBundle::layout.html.twig at line 2 .

My SiteBackendBundle::layout.html.twig file looks like:

{% extends '::base.html.twig' %}
{% form_theme form 'SiteBackendBundle:Form:fields.html.twig' %}
{% block body %}
....
{% endblock %}

and my SiteBackendBundle:Form:fields.html.twig looks like this:

{% block money_widget %}
{% spaceless %}
  {{ block('form_widget_simple') | raw }}
{% endspaceless %}
{% endblock %}

My config.yml for Symfony/forms looks like this:

framework:
    #esi:             ~
    translator:      { fallback: en }
    secret:          %secret%
    router:
        resource: "%kernel.root_dir%/config/routing.yml"
        strict_requirements: %kernel.debug%
    form:            ~
    csrf_protection: ~
    validation:      { enable_annotations: true }
    templating:
        engines: ['twig']
        #assets_version: SomeVersionScheme
    default_locale:  "%locale%"
    trusted_proxies: ~
    session:         ~
    fragments:       ~

It's also weird because this was working before I ran php app/console cache:clear

Why am I unable to extend the form without getting this error? This exact method is defined at http://symfony.com/doc/2.2/cookbook/form/form_customization.html#method-2-inside-a-separate-template

Answer 1

If one or more of the twig files that extend your layout do not contain a form then presumably you won't be passing a form variable to them. You can get round this by updating your layout file as follows:

{% if form is defined %}
{% form_theme form 'SiteBackendBundle:Form:fields.html.twig' %}
{% endif %}

Answer 2

I was having the same issue actually. Not sure if this will help but it helped me. In your Controller you have to put in the array like I am doing inside of your return statement.

public function PrefixController extends Controller\
{
    if(...){
    }
    return $this->render('BundleName:ControllerPrefix:TwigTemplate.html.twig', array('form' => $form->createView()));

}