Symfony 4-无法转换属性路径“ [myDateTime]”的值：预期为\\ DateTimeInterface

Question

I want to render a datetime picker using Symfony forms.

Since the datetime picker requires just an input text (because it returns a simple string) I've decided to use the form DataTransformers to transform data from datetime to string and viceversa. But when I try to render my page I get the following error message:

Unable to transform value for property path "[myDateTime]": Expected a \\DateTimeInterface.

My Controller class is the following:

namespace App\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToStringTransformer;
use Symfony\Component\Form\Extension\Core\Type\DateTimeType;
use Symfony\Component\Form\Extension\Core\Type\TextType;
use Symfony\Component\HttpFoundation\Request;

/**
 * Class HomeController
 * @package App\Controller
 */
class HomeController extends Controller
{    
    /**
     * @Route("/test", name="form_test")
     */
    public function testForm(Request $request)
    {
        $data = ['myDateTime' => new \DateTime()];
        $builder = $this->createFormBuilder($data)
            ->add('myDateTime', DateTimeType::class, ['label' => 'My datetime']);

        $builder
            ->get('myDateTime')
            ->addModelTransformer(new DateTimeToStringTransformer(null, null, 'd/m/Y H:i'));

        $form = $builder->getForm();
        $form->handleRequest($request);

        if ($form->isSubmitted() && $form->isValid()) {
            dump($form->getData());
        }

        return $this->render('test.html.twig', [
            'form' => $form->createView(),
        ]);
    }
}

My view template is so simple:

{% extends 'base.html.twig' %}

{% block body %}
    {{ form_start(form) }}
        {{ form_widget(form) }}
        <button class="btn btn-success">{{ button_label|default('Send') }}</button>
    {{ form_end(form) }}
{% endblock %}

To render my datetime picker I've used form themes stored in form/fields.html.twig:

{% use "bootstrap_4_layout.html.twig" %}

{% block datetime_row %}
    <div class="form-group">
        {{ form_label(form) }}
        {{ form_errors(form) }}
        {{ form_widget(form) }}
        {{ form_help(form) }}
    </div>
{% endblock %}

{% block datetime_widget %}
    <div class="input-group date" id="{{ id }}" data-target-input="nearest">
        <input type="text" class="form-control datetimepicker-input" data-toggle="datetimepicker" data-target="#{{ id }}" {% if value %}value="{{ value|e('html_attr') }}"{% endif %}/>
        <div class="input-group-append" data-target="#{{ id }}" data-toggle="datetimepicker">
            <div class="input-group-text"><i class="fa fa-calendar"></i></div>
        </div>
    </div>
{% endblock datetime_widget %}

And added this theme into twig.yaml config file:

twig:
    paths: ['%kernel.project_dir%/templates']
    debug: '%kernel.debug%'
    strict_variables: '%kernel.debug%'
    form_themes:
        - 'bootstrap_4_layout.html.twig'
        - 'form/fields.html.twig'

Does anyone help me to understand why that does not work or what am I doing wrong?

Answer 1

In order to have your form working properly you have to use TextType instead of DateTimeType for your myDateTime field:

$builder = $this->createFormBuilder($data)
        ->add('myDateTime', TextType::class, ['label' => 'My datetime']);

Explanation:

Symfony by default adds a ViewTransformer of type DataTransformerChain for DateTimeType fields. This transformer is called inside normToView function in Form class and expects an argument of \\DateTime class. However by adding the ModelTransformer of type DateTimeToStringTransformer you have already changed the normalized value of myDateTime field to a string and that's why you get the error.

Furthermore, your code won't work even if you use

->addViewTransformer(new DateTimeToStringTransformer(null, null, 'd/m/YH:i'));

instead of

->addModelTransformer(new DateTimeToStringTransformer(null, null, 'd/m/YH:i'));

because in this case the DataTransformerChain transformer is called before the transformer you added and you will get the same error, this time from the DateTimeToStringTransformer .

Answer 2

You don't need the DateTimeToStringTransformer . Remove this Transformer. By default the Symfony DateTimeType expects a \\DateTime object.

So what's happening is your transformer is transforming it to a string and then the DateTimeType is expecting a DateTime but it is getting a string so it's causing this error.

You can read more here: https://symfony.com/doc/current/reference/forms/types/datetime.html#input