Unable to find the association target class - symfony

Question

I'm using Symfony 3.4 and knp doctrine behaviors for translation.
My entity Article looks like:
<?php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;
use Knp\DoctrineBehaviors\Model as ORMBehaviors;
/**
* Article
*
* #ORM\Table(name="article")
* #ORM\Entity(repositoryClass="AppBundle\Repository\ArticleRepository")
*/
class Article
{
use ORMBehaviors\Translatable\Translatable;
/**
* #ORM\Id
* #ORM\Column(type="integer")
* #ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
//...
}
Then I have entity ArticleTranslation
<?php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;
use Knp\DoctrineBehaviors\Model as ORMBehaviors;
/**
* #ORM\Entity
*/
class ArticleTranslation
{
use ORMBehaviors\Translatable\Translation;
/**
* #ORM\Column(type="string", length=128)
*/
protected $headline;
//...
}
Now my app throws me an error:
Unable to find the association target class of "headline" in AppBundle\Entity\Article.
It expects a relation between Article and ArticleTranslation. There is a sentence in the documentation:
The default naming convention (or its customization via trait methods) avoids you to manually handle entity associations. It is handled automatically by the TranslationSubscriber.
Why does this happen? What am I missing?
edit
bin/console doctrine:schema:update
[OK] Nothing to update - your database is already in sync with the current entity metadata.
bin/console debug:config knp_doctrine_behaviors
knp_doctrine_behaviors:
translatable: true
blameable: false
geocodable: false
loggable: false
sluggable: false
soft_deletable: false
sortable: false
timestampable: false
tree: false
I'm using this in sonata admin, with a2lix translatable.
ArticleAdmin.php:
<?php
namespace AppBundle\Admin;
use Sonata\AdminBundle\Admin\AbstractAdmin;
use Sonata\AdminBundle\Datagrid\ListMapper;
use Sonata\AdminBundle\Datagrid\DatagridMapper;
use A2lix\TranslationFormBundle\Form\Type\TranslationsType;
final class ArticleAdmin extends AbstractAdmin
{
protected function configureFormFields(FormMapper $formMapper)
{
$formMapper
->add('headline', TranslationsType::class);
}
//...
}

Answer 1

Try to use
$formMapper->add('translations', TranslationsType::class);
I had the same problem. Probably the field name needs to be exactly translations.