Symfony2 make field entity dynamically - symfony

Question

I have a number of fields of an entity that I see on a page, I would like for each of these fields you can edit them via ajax, one at a time.
To do this I came up with the idea of ​​building a unique controller for all fields, but I can not make it work and I do not know if it is the right solution for what I try to do.
my page show field:
<div>
<form class="ajax" action="{{ path('ajax_setSocial', { 'id': entity.id }) }}" method="post" {{ form_enctype(form) }}>
<div class="editor">
{{ form_errors(form) }}
<div class="editLabel pls lti">{{ form_label(form.ragSocial) }}</div>
<div class="editField">
<div class="ptm">
{{ form_widget(form.ragSocial) }} {{ form_errors(form.ragSocial) }}
</div>
{{ form_widget(form._token) }}
<div class="mtm">
<button class="btn btn-primary disabled save" type="submit" disabled>Save</button>
<button class="btn ann">Cancel</button>
</div>
</div>
</div>
</form>
</div>
<div>
<form class="ajax" action="{{ path('ajax_setSocial', { 'id': entity.id }) }}" method="post" {{ form_enctype(form) }}>
<div class="editor">
{{ form_errors(form) }}
<div class="editLabel pls lti">{{ form_label(form.pIva) }}</div>
<div class="editField">
<div class="ptm">
{{ form_widget(form.pIva) }} {{ form_errors(form.pIva) }}
</div>
{{ form_widget(form._token) }}
<div class="mtm">
<button class="btn btn-primary disabled save" type="submit" disabled>Save</button>
<button class="btn ann">Cancel</button>
</div>
</div>
</div>
</form>
</div>
in my controller:
public function setSocialAction(Request $request, $id)
{
$em = $this->getDoctrine()->getManager();
$entity = $em->getRepository('MyBusinessBundle:Anagrafica')->find($id);
if (!$entity) {
throw $this->createNotFoundException('Unable to find Anagrafic entity.');
}
$field = $request->get('field');
$class = $field.'Type()';
$form = $this->createForm(new $class, $entity);
$form->bind($request);
if ($form->isValid()) {
$em->persist($entity);
$em->flush();
$response = new Response();
$output = array('success' => true);
$response->headers->set('Content-Type', 'application/json');
$response->setContent(json_encode($output));
return $response;
}
$class = $field.'Type()';
$form = $this->createForm(new $class, $entity);
with these lines of code I try to make dynamic class that generates the form field, but does not work because it is being transformed as a string and the error I get is:
Fatal error: Class 'ragSocialType()' not found
but the class is! and is also called to the top file ..
I hope I explained, I accept any advice to follow a better way!

Answer 1

$class = $field.'Type'; //remove the ()
$form = this->createForm(new $class, $entity);