Zend 2: Как использовать метод, определенный в другой модели в моей текущей модели?

Я пытаюсь решить эту проблему по-разному, но, кажется, ничего не работает.
У меня 2 модели:

namespace Admin\Model;

use Zend\Db\TableGateway\TableGateway;

class UsersMetaTable
{
protected $tableGateway;

public function __construct(TableGateway $tableGateway)
{
$this->tableGateway = $tableGateway;
}

public function saveData(UsersMeta $value)
{
...
}

public function getAttachment($user_id){
$user_id  = (int) $user_id;
$rowset = $this->tableGateway->select(array('parent_id' => $user_id,'meta_key' =>'inside_users_attachement'));
$row = $rowset->current();
if (!$row) {
return false;
exit;
}
return $row->meta_value;
}
}

И моя текущая модель:

namespace Admin\Model;

use Zend\Db\TableGateway\TableGateway;

class AttachmentTable
{
protected $tableGateway;

public function __construct(TableGateway $tableGateway)
{
$this->tableGateway = $tableGateway;
}

public function saveData(Attachment $value)
{
...
}

public function getAttachment($user_id)
{
$user_id  = (int) $user_id;

//HERE I NEED TO LOAD UsersMetaTable MODEL AND USE  getAttachment METHOD

$attachment_id = $usersMetaTable->getAttachment($user_id);

if($attachment_id){
$rowset = $this->tableGateway->select(array('ID' => $attachment_id));
$row = $rowset->current();
if (!$row) {
return false;
exit;
}
return $row;
}else{
return false;
}
}
}

В AttachmentTable модель мне нужно использовать метод getAttachment от UsersMetaTable модель. Как я могу сделать это в Zend Franework 2?

Мои две модели определены в Modele.php:

public function getServiceConfig(){
return array(
'abstract_factories' => array(),
'aliases' => array(),
'factories' => array(
'Admin\Model\AttachmentTable' =>  function($sm) {
$tableGateway = $sm->get('AttachmentTableGateway');
$table = new AttachmentTable($tableGateway);
return $table;
},
'AttachmentTableGateway' => function ($sm) {
$dbAdapter = $sm->get('Zend\Db\Adapter\Adapter');
$resultSetPrototype = new ResultSet();
$resultSetPrototype->setArrayObjectPrototype(new attachment()); // Notice what is set here
return new TableGateway('attachments', $dbAdapter, null, $resultSetPrototype);
},
'Admin\Model\UsersMetaTable' =>  function($sm) {
$tableGateway = $sm->get('UsersMetaTableGateway');
$table = new UsersMetaTable($tableGateway);
return $table;
},
'UsersMetaTableGateway' => function ($sm) {
$dbAdapter = $sm->get('Zend\Db\Adapter\Adapter');
$resultSetPrototype = new ResultSet();
$resultSetPrototype->setArrayObjectPrototype(new UsersMeta()); // Notice what is set here
return new TableGateway('inside_users_metas', $dbAdapter, null, $resultSetPrototype);
},
),
'invokables' => array(
// defining it as invokable here, any factory will do too
'my_image_service' => 'Imagine\Gd\Imagine',
),
'services' => array(),
'shared' => array(),
);
}