Symfony2我的提交按钮没有显示在$ form-> createView（）上

Question

New Symfony user here.. I'm experimenting with different ways of creating forms on my own by hand, so I may learn more about how symfony works. I've created a form based on an Entity. The form displays but the submit button does not show up.

/**
 * @Route("/register")
 * @Template()
 */
public function registerAction(Request $request)
{
    $user = new User();
    $form = $this->createForm(new RegisterType(), $user);
    $form->handleRequest($request);
    if ($form->isSubmitted() && $form->isValid()) {
        $user = $form-getData();
        $user->setPassword($this->encodePassword($user, $user->getPlainPassword()));
        $em = $this->getDoctrine()->getManager();
        $em->persist($user);
        $em->flush();
        $url = $this->generateUrl('/home');
        return $this->redirect($url);
    }

    return array(
        'entity' => $user,
        'form'   => $form->createView(),
    );   
}

And for now just a minimal template.

{% extends '::base.html.twig' %}
{% block body -%}
<h1>Register</h1>
{{ form(form) }}
{% endblock %}

And here is the type.

<?php
namespace AppBundle\Form;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;

class RegisterType extends AbstractType {

    /**
     * @param FormBuilderInterface $builder
     * @param array $options
     */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('username', 'text')
            ->add('email', 'email')
            ->add('plainPassword', 'repeated', array(
                'type'=>'password'));
    }


    /**
     * @param OptionsResolverInterface $resolver
     */
    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(array(
            'data_class' => 'AppBundle\Entity\User'
        ));
    }

    /**
     * @return string
     */
    public function getName()
    {
        return 'registration_form';
    }

 }

Answer 1

As I said in my comment, submit type was missing, which leads to a missing submit button. I don't know exactly which example you have been reading, but pretty much most of them have this added in Symfony's official documentation.

More on the subject can be found here.