Doctrine2 OneToMany - ManyToOne returns empty collection with database ok

Have you tried defining your $delegation property like

/**
 * @ORM\ManyToOne(targetEntity="Delegation", inversedBy="promotions")
 * @ORM\JoinColumn(name="delegation_id", referencedColumnName="id")
 */
private $delegation;

See Doctrine2 Docs: Association Mapping->Many-To-One

---

Also there are a lot of typos in your code. For example

/**
 * @ORM\OneToMany(targetEntity="Promotion", mappedBy="delegacion", cascade={"all"}, orphanRemoval=true)
 */
protected $promotions;

mappedBy="delegacion" should be mappedBy="delegation".

Or

public function getDeleTacion()
{
    return $this->deleTacion;
}

Should be

public function getDelegation()
{
    return $this->delegation;
}

Edit

Okay, I created a minimalistic version for you that worked for me. You can built it up from there or watch for differences with your code:

Promotion.php

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 */
class Promotion
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /**
     * @ORM\ManyToOne(targetEntity="Delegation", inversedBy="promotions", cascade={"persist"})
     * @ORM\JoinColumn(name="delegation_id", referencedColumnName="id")
     */
    public $delegation;

    /**
     * @ORM\ManyToOne(targetEntity="Product", inversedBy="promotions", cascade={"persist"})
     * @ORM\JoinColumn(name="product_id", referencedColumnName="id")
     */
    public $product;
}

Delegation.php

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 */
class Delegation
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /**
     * @ORM\OneToMany(targetEntity="Promotion", mappedBy="delegation", cascade={"all"}, orphanRemoval=true)
     */
    public $promotions;

    public function __construct() {
        $this->promotions = new \Doctrine\Common\Collections\ArrayCollection();
    }
}

Product.php

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 */
class Product
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /**
     * @ORM\OneToMany(targetEntity="Promotion", mappedBy="product", cascade={"all"}, orphanRemoval=true)
     */
    public $promotions;

    public function __construct() {
        $this->promotions = new \Doctrine\Common\Collections\ArrayCollection();
    }
}

If you now do something like

$delegation = new Delegation();
$product = new Product();
$promotion = new Promotion();
$promotion->delegation = $delegation;
$promotion->product = $product;

$em->persist($promotion);
$em->flush();

$products = $em->createQuery('select p from BundleName\Entity\Product p')->execute();
$delegations = $em->createQuery('select d from BundleName\Entity\Delegation d')->execute();

var_dump(count($products[0]->promotions), count($delegations[0]->promotions));

You should end up with

int(1)
int(1)

So the refrence is in fact saved and can be read. Phew. Good luck with that! :-)