php - Get only list of ID's from ManyToMany with Doctrine -

i have manytomany associated field, , i'm in situation i'm trying id's without hydrating of sub-entities in field.

i understand there query aquire entity references moment access field, , that's fine/expected. need loop through id's, don't quite know how them without doing

$ids = []; foreach($mainentity->getsubentities() $subentity) {    $ids[] = $subentity->getid(); } 

this seems hydrate sub entity automatically, im assuming because of foreach loop. results in lot of unnecessary queries , impacts page load time.

i have subentity field marked extralazy well.

/**  * @var arraycollection  * @orm\manytomany(targetentity="user", fetch="extra_lazy")  * @orm\jointable(name="user_friends")  */ protected $friends; 

doctrine's arraycollection class provides method called: getkeys().

using can create new method extract ids collection follows:

public function getfriendids() {     return $this->friends->getkeys(); } 

doctrine map entity primary key collection key unless otherwise specified. solve you're problem.