Question

If I have the following class defined,

class Category {

    /**
     *
     * @var integer $id
     * @Column(name="id", type="integer",nullable=false)
     * @Id
     * @GeneratedValue(strategy="IDENTITY")
     */
    protected $id;

     /**
     *
     * @ManyToMany(targetEntity="Tag")
     * @JoinColumn(onDelete="SET NULL")
     */
    protected $tags;
}

Shouldn’t I be able to get all the tags associated to this category by:

$categoryTags = $category->getTags();

The object in $categoryTags after the above assignment is of the type Doctrine\ORM\PersistentCollection while I expect it to be an array.

I added the association values in category_tag table manually with sql commands, but I can see that they are valid.

My Tags class looks like this:

class Tag extends Tag{

    /**
     *
     * @var integer $id
     * @Column(name="id", type="integer",nullable=false)
     * @Id
     * @GeneratedValue(strategy="IDENTITY")
     */
    protected $id;


    /**
     * @Column(type="string",length=60,nullable=false)
     * @var string
     */
    protected $tag;

}

Answer 1

Doctrine does not return simple arrays for associated entity collections. Rather, it returns implementations of Doctrine\Common\Collections\Collection.

You can use these as you would an array as they extend the Countable, IteratorAggregate and ArrayAccess interfaces.

If you really need an array (and I can’t think of a reason why), you can use the toArray() method.

Please read the documentation to understand why Doctrine does not use simple arrays

• http://doctrine-orm.readthedocs.org/en/latest/reference/association-mapping.html?highlight=many-to-many#collections
• http://doctrine-orm.readthedocs.org/en/2.0.x/reference/architecture.html#persistent-fields