How to properly remove an item in a ManyToOne uni-directional relation with Doctrine?

Question:How to properly remove an item in a ManyToOne relation

Context:Php 7.3 / Symfony 4 / Doctrine 2.7 / Api-platform 2.5

Description:

I have the following entities:

The Image class definition

use ApiPlatform\Core\Annotation\ApiResource;use ApiPlatform\Core\Annotation\ApiProperty;use Doctrine\ORM\Mapping as ORM;/** * Class Image * @package App\Entity * * @ApiResource(...) * @ORM\Entity */class Image extends Media{    /**     * @ApiProperty()     * @ORM\Column(type="guid")     * @ORM\Id     * @var null|string     */    protected $id;     /* ... properties */     /* ... getters/setters */}

The Foo class definition:

use ApiPlatform\Core\Annotation\ApiResource;use ApiPlatform\Core\Annotation\ApiProperty;use Doctrine\ORM\Mapping as ORM;/** * Class Foo * @package App\Entity * * @ApiResource(...) * @ORM\Entity */class Foo{    /**     * @ApiProperty()     * @ORM\Column(type="guid")     * @ORM\Id     * @var null|string     */    protected $id;     /**     * @var array|null     * @ApiProperty()     * @ORM\Mapping\ManyToOne(targetEntity="App\Entity\Image",cascade={"remove"},fetch="EAGER")     */    private $image;    public function getImage()    {        return $this->image;    }    public function setImage($image): void    {        $this->image = $image;    }    /* ... other properties */     /* ... getters/setters */}

The Bar class definition:

class Bar{    /* ... property id */    /**     * @var array|null     * @ApiProperty()     * @ORM\Mapping\ManyToOne(targetEntity="App\Entity\Image",cascade={"remove"},fetch="EAGER")     */    private $image;    public function getImage()    {        return $this->image;    }    public function setImage($image): void    {        $this->image = $image;    }    /* ... other properties */     /* ... getters/setters */}

In my current architecture:

• two entities reference the same Image entity via an un-idirectional ManyToOne relation,
• a single image may be referenced by several resources
  • Two Foo instances may have a relation to the same Image instance
  • One Foo instance and one Bar instance may have a relation to the same Image instance

Question/Issue:

In my controller, when I delete a resource (Foo or Bar), I want to automatically delete the image (in my database) if none reference are left to this image. how to handle such behavior ?

I try to modify the doctrine annotation in my Foo (and Bar) class to trigger the delete cascade :@ORM\Mapping\ManyToOne(targetEntity="App\Entity\Image",cascade={"remove"},fetch="EAGER") ; but in this case, an exception is raised if a reference still exists on the image.

And as the orphanRemoval flag does not exist on a ManyToOne relation, I am stuck to identify the right configuration/solution.

Any help is welcome ...