Relationship between two entities - entity-framework

Question

I have a trouble and I need your assistance. Now I create two entities :
Partner
PartnerMedia
Partner entity contains all information about my partners and the other entity, have relationship with Partner and Sonata Media Entity.
There is what contains my partner entity :
<?php
namespace AppBundle\Entity;
use AppBundle\Entity\CMS\Block;
use AppBundle\Entity\SuperClass\SortableTranslatableEntity;
use Doctrine\ORM\Mapping as ORM;
use Gedmo\Mapping\Annotation as Gedmo;
use Sonata\MediaBundle\Model\Media;
use Doctrine\Common\Collections\ArrayCollection;
use Sonata\TranslationBundle\Model\Gedmo\TranslatableInterface;
/**
* Partner.
*
* #ORM\Table("partner")
* #ORM\Entity
*/
class Partner extends SortableTranslatableEntity implements TranslatableInterface
{
/**
* #var int
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #var string
*
* #ORM\Column(name="libelle", type="string", length=60)
* #Gedmo\Translatable
*/
private $libelle;
/**
* #var string
*
* #ORM\Column(name="mea", type="boolean")
*/
private $mea;
/**
* #ORM\OneToMany(targetEntity="\AppBundle\Entity\Media\PartnerMedia", mappedBy="partner", cascade={"persist"}, orphanRemoval=true)
* #ORM\OrderBy({"position" = "ASC"})
*/
private $medias;
/**
* #ORM\Column(type="string", name="url", nullable=true)
* #Gedmo\Translatable
*/
private $url;
/**
* #ORM\ManyToOne(targetEntity="\AppBundle\Entity\CMS\Block", inversedBy="block")
*/
private $block;
public function __construct()
{
$this->medias = new ArrayCollection();
}
public function setTranslatableLocale($locale)
{
$this->locale = $locale;
}
public function getContextName()
{
return 'partner';
}
public function __toString()
{
return $this->getId() ? (string) $this->getLibelle() : '-';
}
public function firstPhoto()
{
if ($this->getMedias() && $this->getMedias()->count()) {
return $this->getMedias()->first()->getMedia();
}
}
public function getId()
{
return $this->id;
}
public function getLibelle()
{
return $this->libelle;
}
/**
* Add medias.
*
* #param PartnerMedia $media
*
* #return PartnerMedia
*/
public function addMedias(PartnerMedia $media)
{
$media->setPartner($this);
$this->medias[] = $media;
return $this;
}
/**
* Remove medias.
*
* #param PartnerMedia $media
*/
public function removeMedia(PartnerMedia $media)
{
$this->medias->removeElement($media);
}
public function getMedias()
{
return $this->medias;
}
public function getUrl()
{
return $this->url;
}
/**
* Get page.
*
* #return \AppBundle\Entity\CMS\Block
*/
public function getBlock()
{
return $this->block;
}
public function setId($id)
{
$this->id = $id;
}
public function setLibelle($libelle)
{
$this->libelle = $libelle;
}
public function setUrl($url)
{
$this->url = $url;
}
/**
* Set page.
*
* #param \AppBundle\Entity\CMS\Block $block
* #return Partner
*/
public function setBlock(Block $block = null)
{
$this->block = $block;
return $this;
}
/**
* Set mea
*
* #param boolean $mea
* #return Partner
*/
public function setMea($mea)
{
$this->mea = $mea;
return $this;
}
/**
* Get mea
*
* #return boolean
*/
public function getMea()
{
return $this->mea;
}
/**
* #param mixed $medias
*/
public function setMedias($medias)
{
$this->medias = $medias;
}
}
and what contains PartnerMedia entity :
<?php
/**
* PartnerMedia
*
* #ORM\Table()
* #ORM\Entity
*/
class PartnerMedia extends SortableEntity
{
/**
* #var int
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #ORM\ManyToOne(targetEntity="\Application\Sonata\MediaBundle\Entity\Media")
*/
private $medias;
/**
* #ORM\ManyToOne(targetEntity="\AppBundle\Entity\Partner", inversedBy="partner")
*
* #Gedmo\SortableGroup
*/
private $partner;
/**
* Get id
*
* #return integer
*/
public function getId()
{
return $this->id;
}
/**
* Set medias
*
* #param Media $medias
* #return PartnerMedia
*/
public function setMedias(Media $medias = null)
{
$this->medias = $medias;
return $this;
}
/**
* Get medias
*
* #return Media
*/
public function getMedias()
{
return $this->medias;
}
/**
* Set Partner
*
* #param Partner $partner
* #return PartnerMedia
*/
public function setPartner(Partner $partner = null)
{
$this->partner = $partner;
return $this;
}
/**
* Get Partner
*
* #return Partner
*/
public function getPartner()
{
return $this->partner;
}
public function getContextName()
{
return 'partner_media';
}
public function __construct()
{
$this->medias = new ArrayCollection();
}
}
Now when I tried to create a new partner, I receive that exception :
The current field medias is not linked to an admin. Please create one for the target entity : AppBundle\Entity\Media\PartnerMedia
I need your assistance please and thanks

Answer 1

The error message you describe sounds more like a Sonata Admin error.
One of the things about sonata admin is that when you are creating links between entities, you need to have admin classes built for both entity classes.
More than likely, you're trying to test your code before completely implementing the admins necessary to do so.