public static function add($lat, $lng, $radius, $id)
 {
     $model = Point_of_interest::firstByAttributes(array('circle_id' => $id));
     if (!$model) {
         $model = new Point_of_interest();
     }
     $model->name = '';
     $model->poi_type_id = 1;
     $model->poi_category_id = 1;
     $model->cover_photo = 'test';
     $model->node_id = 1;
     $model->venue_id = 1;
     $model->latitude = $lat;
     $model->longitude = $lng;
     $model->radius = $radius;
     $model->circle_id = $id;
     if ($model->save()) {
         return TRUE;
     }
     return FALSE;
 }