Doctrine inserting problem - Many To One relation - Example

Categories.php

<?php 
namespace models;

use InvalidArgumentException;

/**
 * @Entity
 * @Table(name="categories")
 */
class Categories {
	/**
	 * @Id
	 * @Column(name="id", type="integer", nullable=false)
	 * @GeneratedValue(strategy="AUTO")
	 */
	protected $id;
	
	/**
	 * @var Languages|null language id this category belongs to
	 * @ManyToOne(targetEntity="Languages", inversedBy="categories")
	 * @JoinColumn(name="languages_id", referencedColumnName="id")
	 */
	protected $languages;
	
	/**
	 * @Column(type="integer", nullable=false)
	 */
	protected $parent_id;
	
	/**
	 * @Column(type="string", length="255", nullable=false)
	 */
	protected $title;

	
	/* Setters & Getters */
	public function getId(){ return $this->id; }
	
	public function setLanguage($lang){ 
		if($lang === null) {
            if($this->languages !== null) {
                $this->languages->getCategories()->removeElement($this);
            }
            $this->languages = null;
        } else {
            if(!$lang instanceof Languages) {
                throw new InvalidArgumentException('$lang must be null or instance of models\Languages');
            }
            if($this->languages !== null) {
                $this->languages->getCategories()->removeElement($this);
            }
            $this->languages = $lang;
            $lang->getCategories()->add($this);
        }
	}
	public function getLanguage(){ return $this->languages; }
	
	public function setParentId($parent){ $this->parent_id = $parent; }
	public function getParentId(){ return $this->parent_id; }	
	
	public function setTitle($title){ $this->title = $title; }
	public function getTitle(){ return $this->title; }
}

Insert.php

$data = $this->input->post();
		if( is_array($data) && count($data) )
		{
			unset($data['submit']);
			
			$add = new models\Categories();
			$add->setLanguage($this->em->getReference('models\Languages',$data['language_id']));
			$add->setParentId($data['parent']);
			$add->setTitle($data['title']);
			$this->em->persist($add);
			$this->em->flush();

			if( $add->getId() )
			{
				$this->session->set_flashdata('message','Kategorija je dodana!');
				redirect('admin/kategorije');
			}
			else
			{
				$this->session->set_flashdata('message','Kategorija ni dodana!');
				redirect('admin/kategorije');
			}
		}

Languages.php

<?php 
namespace models;

use Doctrine\Common\Collections\Collection,
    Doctrine\Common\Collections\ArrayCollection;

/**
 * @Entity
 * @Table(name="languages")
 */
class Languages {
	/**
	 * @Id
	 * @Column(name="id", type="integer", nullable=false)
	 * @GeneratedValue(strategy="AUTO")
	 */
	protected $id;
	
	/**
	 * @Column(type="string", length="255", nullable=false)
	 */
	protected $title;
	
	/**
	 * @Column(type="string", length="255", nullable=false)
	 */
	protected $slug;
	
	/**
	 * @Column(type="string", length="255", nullable=false)
	 */
	protected $icon;
	
	/**
	 * @var Collection
	 * @OneToMany(targetEntity="models\Categories", mappedBy="languages")
	 */
	protected $categories;

	
	public function __construct()
	{
		$this->categories = new ArrayCollection();
	}
	
	
	/* Setters & Getters */
	public function getId(){ return $this->id; }
	
	public function setIcon($icon){ $this->icon = $icon; }
	public function getIcon(){ return $this->icon; }
	
	public function setSlug($slug){ $this->slug = $slug; }
	public function getSlug(){ return $this->slug; }	
	
	public function setTitle($title){ $this->title = $title; }
	public function getTitle(){ return $this->title; }
	
	public function getCategories(){ return $this->categories; }
}

Thanks, it worked for me.
Dziękuję ;)