Doctrine2多对多不返回数组

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