gistfile1.php

    /**
      * Products.
      * 
      * @OneToMany(targetEntity="Sylius\AssortmentBundle\Entity\Product", mappedBy="category")
      */
     protected $products;

    /* ... */

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

    /* ... */

    /**
      * Category.
      * 
      * @orm:ManyToOne(targetEntity="Sylius\AssortmentBundle\Entity\Category")
      * @orm:JoinColumn(name="category_id", referencedColumnName="id")
     */
    protected $category = null;