Zend Framework 2 Custom elements using ServiceManager not work - zend-framework2

Question

I want create a custom element and use the short name for add the element into Form, using the new ServiceManager tecnique for ZF2 V.2.1+
I am try to copy the same sample of the zend documentation step to step but it not works.
When I use the service writting the short name, it raises a exception because service not found:
Zend\ServiceManager\Exception\ServiceNotFoundException
File:
Zend\ServiceManager\ServiceManager.php:456
Message:
Zend\ServiceManager\ServiceManager::get was unable to fetch or create an instance for Test
I think I have all classes identically, see follows
This is my custom element:
namespace SecureDraw\Form\Element;
use Zend\Form\Element\Text;
class ProvaElement extends Text {
protected $hola;
public function hola(){
return 'hola';
}
}
This is my Module.php I have my invokable service be able to use short name:
class Module implements FormElementProviderInterface {
//Rest of class
public function getFormElementConfig() {
return array(
'invokables' => array(
'Test' => 'SecureDraw\Form\Element\ProvaElement'
)
);
}
}
In my form I use for add the element, the commented line works ok, but with short name not works:
$this->add(array(
'name' => 'prova',
//'type' => 'SecureDraw\Form\Element\ProvaElement',
'type' => 'Test', //Fail
));
In my action:
$formManager = $this->serviceLocator->get('FormElementManager');
$form = $formManager->get('SecureDraw\Form\UserForm');
$prova = $form->get('prova');
echo $prova->hola();

Answer 1

The problem is that the elements created via FormElementManager have to be created into init method instead __Construct method how it can see in this page.
The zend documentation is badly explained

Answer 2

Workaround:
In your own module, create the following two files:
FormElementManagerConfig with the invokables short names of your custom form elements;
Subclass Form\Factory and override getFormElementManager and pass the config to the FormElementManager constructor;
You then use your own Factory to create your Form, like this (you can pass a very rudimentary, e.g. empty array, or a more or less full-fledged $spec to $factory->createForm()):
$factory = new Factory();
$spec = array();
$form = $factory->createForm($spec);
FormElementManagerConfig.php:
class FormElementManagerConfig implements ConfigInterface
{
protected $invokables = array(
'anything' => 'MyModule\Form\Element\Anything',
);
public function configureServiceManager(ServiceManager $serviceManager)
{
foreach ($this->invokables as $name => $service) {
$serviceManager->setInvokableClass($name, $service);
}
}
}
MyFactory.php:
class Factory extends \Zend\Form\Factory
{
public function getFormElementManager()
{
if ($this->formElementManager === null) {
$this->setFormElementManager(new FormElementManager(new FormElementManagerConfig()));
}
return $this->formElementManager;
}
}