Error trying to extend SonataMediaBundle “Impossible to invoke a method (”id“) on a null variable”

Question

I'm trying to extend the media class of SonataMediaBundle. I want to generate my own media to add more relations and properties.

But now I am stuck with this error:

Impossible to invoke a method ("id") on a null variable in SonataDoctrineORMAdminBundle:Form:form_admin_fields.html.twig at line 59.

My service declaration is:

services:
    gallery.admin.image:
        class: GalleryBundle\Admin\ImageAdmin
        arguments: [~, GalleryBundle\Entity\Image, SonataMediaBundle:MediaAdmin, @sonata.media.pool, @sonata.classification.manager.category]
        tags:
            - { name: sonata.admin, manager_type: orm, group: sonata_media, label_catalogue: SonataMediaBundle, label: Gallery}
        calls:
            - [ setModelManager, [@sonata.media.admin.media.manager]]
            - [ setTranslationDomain, [SonataMediaBundle]]
            - [ setTemplates, [[inner_list_row: SonataMediaBundle:MediaAdmin:inner_row_media.html.twig, outer_list_rows_mosaic: SonataMediaBundle:MediaAdmin:list_outer_rows_mosaic.html.twig, base_list_field: SonataAdminBundle:CRUD:base_list_flat_field.html.twig, list: SonataMediaBundle:MediaAdmin:list.html.twig, edit: SonataMediaBundle:MediaAdmin:edit.html.twig]]]

My admin class is:

use Sonata\AdminBundle\Datagrid\DatagridMapper;
use Sonata\AdminBundle\Form\FormMapper;
use Sonata\ClassificationBundle\Model\CategoryManagerInterface;
use Sonata\MediaBundle\Admin\BaseMediaAdmin;
use Sonata\MediaBundle\Admin\ORM\MediaAdmin;
use Sonata\MediaBundle\Provider\Pool;

class ImageAdmin extends BaseMediaAdmin
{
    public function __construct($code, $class, $baseControllerName, Pool $pool, CategoryManagerInterface $categoryManager)
    {
        parent::__construct($code, $class, $baseControllerName, $pool, $categoryManager);
    }

    protected function configureFormFields(FormMapper $formMapper)
    {
        $formMapper
            ->with('Basic')
            ->add('tags', 'sonata_type_model', [
                'multiple' => true,
            ])
            ->end()
        ;
        parent::configureFormFields($formMapper);
    }
}

And my Entity is:

use BlogBundle\Entity\PostTag;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\ORM\Mapping as ORM;
use Sonata\MediaBundle\Model\Media;

/**
 * Image
 *
 * @ORM\Table(name="image")
 * @ORM\Entity(repositoryClass="GalleryBundle\Repository\ImageRepository")
 */
class Image extends Media
{
    /**
     * @var int
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @ORM\ManyToMany(targetEntity="BlogBundle\Entity\PostTag", inversedBy="gallery_images")
     */
    protected $tags;

    public function __construct()
    {
        $this->tags = new ArrayCollection();
    }

    /**
     * Get id
     *
     * @return int
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * Add tag.
     *
     * @param PostTag $tag
     *
     * @return Image
     */
    public function addTag(PostTag $tag)
    {
        $this->tags[] = $tag;

        return $this;
    }

    /**
     * Remove tag.
     *
     * @param PostTag $tag
     */
    public function removeTag(PostTag $tag)
    {
        $this->tags->removeElement($tag);
    }

    /**
     * Get tags.
     *
     * @return Collection
     */
    public function getTags()
    {
        return $this->tags;
    }
}

I know that the problem would be fixed using the next version. But with our current server we cannot upgrade. The project is already on production, and I can't afford to remake it.

I have seen that the problem was because I would have more than one sonata_type_model , in the definition of the admin. But no matter how much I delete the relation with PostTags the error persists.

I don't know if the service definition is wrong or I have forgotten an event call or something.

I would appreciate any help. Thanks

Answer 1

My suggestions are:

When you are creating your builder, use 'empty_on_new' => false.

empty_on_new (default is true): the related data transformer will return null instead of an empty Media instance if no binary content is provided

https://sonata-project.org/bundles/media/3-x/doc/reference/form.html

And you have a ManyToMany relation with PostTags.

Why doesn't you use 'sonata_type_collection' in your ImageAdmin instead of 'sonata_type_model' ?

https://sonata-project.org/bundles/admin/master/doc/reference/form_types.html#sonata-corebundle-form-type-collectiontype

I hope it will help you.

Good luck !