I have this error
Trying to get property of non-object
php code

($model->creator_id) ? $model->creator->firstname . ' ' . $model->creator->lastname : 'Нет',

model relations:

public function relations()
{
// NOTE: you may need to adjust the relation name and the related
// class name for the relations automatically generated below.
return array(
'creator' => array(self::BELONGS_TO, 'User', 'creator_id'),
'creator' => array(self::HAS_MANY, 'User', 'creator_id'),
);
}