Symfony and Bootstrap dateTimePicker : expected a string

Question

I am trying to create a DateTimePickerType to easily add a Bootstrap dateTimePicker to a field, simply by using the type "date_time_picker" in the Form Builder.
Unfortunately I am running into some problems. Specifically, Symfony is giving me this error :

Symfony\\Component\\Validator\\ConstraintViolation
Object(Symfony\\Component\\Form\\Form).children[startDate] = Object(DateTime) - 2016-10-16T10:45:00+0200
Caused by:
Symfony\\Component\\Form\\Exception\\TransformationFailedException
Unable to reverse value for property path "startDate": Expected a string. Caused by:
Symfony\\Component\\Form\\Exception\\TransformationFailedException
Expected a string.

So apparently my form is sending a DateTime object to my Controller, who has trouble converting it to String. In the database, the field is of type datetime.

Here is my DateTimePickerType :

class DateTimePickerType extends AbstractType
{
    /**
     * @return string
     */
    public function getParent()
    {
        return 'datetime';
    }

    /**
     * @param OptionsResolverInterface $resolver
     */
    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {

        $resolver->setDefaults(
            array(
                'empty_data' => new \DateTime(),
                'widget' => "single_text",
                'attr' => array(
                    'class' => 'addInput col-xs-12 dateSize noPadding noOutline dateTimePicker',
                ),
                'format' => 'YYYY-MM-DD HH:mm',
                'date_format'=>"dd/MM/yyyy hh:mm",
                'html5'    => false,
            )
        );
    }

    /**
     * @param FormView $view
     * @param FormInterface $form
     * @param array $options
     */
    public function buildView(FormView $view, FormInterface $form, array $options)
    {
        $view->vars = array_replace($view->vars, array(
            'empty_data' => $options['empty_data'],
            'widget' => $options['widget'],
            'format' => $options['date_format'],
        ));
    }

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

I have tried many different options for the resolver. If I remove the "new \\DateTime()" in "empty_data", my form now sends a null value, and I get a nice SQL error trying to insert null into the database.

Snippet of form_template.html.twig :

{% block date_time_picker_widget %}
    <div class='input-group date' id='date-time-picker-{{ id }}'>
        <input type="text" class="form-control" />
        <span class="input-group-addon"><i class="fa fa-clock-o"></i></span>
    </div>
    {% include 'VMSFormTypeBundle:Template:date_time_picker_script.html.twig' %} {# link to the direct js script to make it datetimepicker #}
{% endblock %}

In date_time_picker_script.html.twig :

{% autoescape false %}
    <script type="text/javascript">
        $(function () {
            $('#date-time-picker-{{ id }}').datetimepicker();
        });
    </script>
{% endautoescape %}

Snippet of my Form Builder :

$builder
->add('startDate','date_time_picker')

Thanks in advance

EDIT : Just noticed the datetime that is sent by the form ignores what I select, and instead sends the current datetime (current day, hour and minute).

Answer 1

Apparently this is because there's a need to convert the time format between PHP and JS. I fixed the problem by using only a DateType (time wasn't that necessary).

This might be useful for those who still need a DateTime, tho I haven't tested it : https://github.com/stephanecollot/DatetimepickerBundle