Two form fields into one entity value

Question

How its possible to join two separated fields (must be separated) in one form (date and time for example) to one entity propery datetime for persisting after form post ?

What is better way ? Data Transofmers ? Form events ? Form Model ? Manual setting all entity properties before persist ?

Entity:

<?php namespace Acme\DemoBundle\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 * @ORM\Table(name="event")
 */
class EventEntity
{

    /**
     * @ORM\Column(name="id", type="integer", nullable=false)
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="IDENTITY")
     */
    private $id;

    // ...

    /**
     * @ORM\Column(name="date_time", type="datetime", nullable=false)
     */
    protected $datetime;

    public function getId()
    {
        return $this->id;
    }

    // ...

    public function getDateTime()
    {
        return $this->datetime;
    }

    public function setDateTime(\DateTime $datetime)
    {
        $this->datetime = $datetime;
    }

}

FormType:

<?php namespace Acme\DemoBundle\Form\Type;

use JMS\DiExtraBundle\Annotation as DI;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;

class EventType extends AbstractType
{

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            // ...
            ->add('date', 'date', [
                    'required' => true,
                    'widget'   => 'single_text',
                    'format'   => 'dd.MM.yyyy'
                ]
            )
            ->add('time', 'time', [
                    'required' => false,
                    'widget'   => 'single_text'
                ]
            );
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(array(
            'data_class' => 'Acme\DemoBundle\Entity\EventEntity' //Acme\DemoBundle\Form\Model\EventModel ?
        ));
    }

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

}

Answer 1

If you set the date and time widget seperately in the datetime type, then they get seperately rendered, but validated as one field.

public function buildForm(FormBuilderInterface $builder, array $options)
{
    $builder->add('datetime', 'datetime', array(
            'date_widget' => 'single_text',
            'time_widget' => 'single_text',
            'date_format' => 'dd.MM.yyyy',
        ));
}