Doctrine: Multidimensional Arrays in Doctrine 2

Question

I am working with Symfony2 and Doctrine2 and I have an object that needs to implement multiple arrays of arrays. The only solution I came up with is to create a bridge object between my main object and the object it is referencing.

So this would be my object:

/**
 * @ORM\Table()
 */
class MyObject
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @ORM\OneToMany(targetEntity="CollectionOfObjectX", mappedBy="parent", cascade={"all"})
     **/
    private $collectionsOfObjectX;

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

    ... (Getters and Setters)

}

This would be the Bridge between the object and some other object

/**
 * @ORM\Table()
 */
class CollectionOfObjectX
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @ORM\ManyToOne(targetEntity="ObjectX",     inversedBy="collectionsOfObjectX", cascade={"all"})
     * @ORM\JoinColumn(name="parent_id", referencedColumnName="id")
     **/
    private $parent;

    /**
     * @ORM\ManyToMany(targetEntity="MyObject",     cascade={"all"})
     * @ORM\JoinTable(
     *      joinColumns={@ORM\JoinColumn(name="local_id", referencedColumnName="id")},
     *      inverseJoinColumns={@ORM\JoinColumn(name="foreign_id", referencedColumnName="id")}
     *      )
     **/
    private $items;

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

.... (Getters and Setters)

}

And this would be the referenced object

/**
 * @ORM\Table()
 */
class ObjectX
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;  

... (Some Properties, Getters and Setters)
}  

So while this works, it requires a Bridge Object for each possible relation between MyObject and any other object it references, implying a lot of duplicate code.

Is there a better way?

Answer 1

Doctrine 2 does not genuinely provide n-2-n abstract relationship. Object A must be a known class, and it should reference Object B (also a known class).

I would suggest trying something like this, to workaround

/**
 * @ORM\Table()
 */
class MyObject
{
   /**
    * @var integer
    *
    * @ORM\Column(name="id", type="integer")
    * @ORM\Id
    * @ORM\GeneratedValue(strategy="AUTO")
    */
   private $id;

   /**
    * @ORM\OneToMany(targetEntity="CollectionOfObjectXYZ", mappedBy="parent", cascade={"all"})
    **/
   private $collectionsOfObjectXYZ;

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

   ... (Getters and Setters)

}

Notice the missing Annotations

/**
 * @ORM\Table()
 */
class CollectionOfObjectXYZ
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @ORM\ManyToOne(targetEntity="MyObject",     inversedBy="collectionsOfObjectXYZ", cascade={"all"})
     * @ORM\JoinColumn(name="parent_id", referencedColumnName="id")
     **/
    private $parent;

    private $items;

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

    public function addItem($item){
        /** EDIT : since we store the relation in the final object (X Y Z), we don't need particular annotation here **/
        $item->setCollectionOfObjectXYZ($this);
        return $this;
    }

.... (Getters and Setters)

}

/**
 * @ORM\Table()
 */
class ObjectX
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;  

    /**
     * @var CollectionOfObjectXYZ
     *
     * @ORM\ManyToOne(target="CollectionOfObjectXYZ", cascade={"persist"})
     */
    private $colletion;

... (Some Properties, Getters and Setters)
}  

/**
 * @ORM\Table()
 */
class ObjectY
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @var CollectionOfObjectXYZ
     *
     * @ORM\ManyToOne(target="CollectionOfObjectXYZ", cascade={"persist"})
     */
    private $colletion;

... (Some Properties, Getters and Setters)
}  

Let me know if it helps.