Why the Symfony form is "not submitted" after data is correctly sent through AJAX?

I want to sent a Symfony form through AJAX (AngularJS).

However, even if data is clearly sent, the form is said by Symfony to be "not submitted" (no error actually, but some debug show that isSubmitted returns false)

Here is a test on FOSUserBundle registration form.

EDIT: although pictures appear small, they are sufficiently resolved so that they are perfectly readable if dispayed at their full size.

Here are the logs when I use a standard submission from an HTTP form:

Here are the logs when I use AJAX submission:

• I have disabled CSRF token


• The method I use from AJAX is "post" so it should be ok since it is the default Symfony expects (and FOSUserBundle does not override that default AFAIK).


• Other forms (outside of FOSUserBundle scope) are correctly sent with AJAX

Would you have any idea on the matter? Any pointer? Or any other log I could check?

EDIT:

I use the default FOSUserBundle registration controller.

I almost use the default FOSUserBundle registration form, but I have added a (currently) empty child form wich I'll need it further in the development.

namespace NONG\SecurityBundle\Form;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;

class UserRegistrationType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options) {}

    public function getParent() {
        return 'fos_user_registration';
    }

    public function getName() {
        return 'nong_user_registration';
    }
}

Headers and data sent with the HTML form (NB. added a dot before star in Accept so that the coloration stays correct):

POST /server/web/testfosuser/register/ HTTP/1.1
Host: mywebsite.com
Connection: keep-alive
Content-Length: 229
Cache-Control: max-age=0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/.*;q=0.8
Origin: http://mywebsite.com
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36         (KHTML, like Gecko) Chrome/40.0.2214.111             Safari/537.36
Content-Type: application/x-www-form-urlencoded
Referer: http://ift.tt/17St4kA
Accept-Encoding: gzip, deflate
Accept-Language: fr-FR,fr;q=0.8,en-US;q=0.6,en;q=0.4
Cookie: PHPSESSID=xxxxxxxxxxxxxxxxxxxxxxxxx


fos_user_registration_form%5Bemail%5D=bidon%40bidon.com&
fos_user_registration_form%5Busername%5D=bidon&
fos_user_registration_form%5BplainPassword%5D%5Bfirst%5D=bidon&
fos_user_registration_form%5BplainPassword%5D%5Bsecond%5D=bidon

Headers sent with the AJAX request: (NB. added a dot before star in Accept so that the coloration stays correct):

POST /server/web/testfosuser/register HTTP/1.1
Host: mywebsite.com
Connection: keep-alive
Content-Length: 229
Accept: application/json, text/plain, */.*
Origin: http://mywebsite.com
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.111 Safari/537.36
Content-Type: application/json;charset=UTF-8 application/x-www-form-urlencoded; charset=UTF-8
Referer: http://ift.tt/1acxwwr
Accept-Encoding: gzip, deflate
Accept-Language: fr-FR,fr;q=0.8,en-US;q=0.6,en;q=0.4
Cookie: PHPSESSID=xxxxxxxxxxxxxxxxxxxxxxxxx

fos_user_registration_form%5Bemail%5D=bidonqdsfqsdf%40qsdf&
fos_user_registration_form%5Busername%5D=charles222&
fos_user_registration_form%5BplainPassword%5D%5Bfirst%5D=bidon&
fos_user_registration_form%5BplainPassword%5D%5Bsecond%5D=bidon