php - How to organize multiselect dropdownlist using kartik-select2 extension -

i need organize multiselect dropdownlist. tried this:

<?= $form->field($model, 'receiver_id')->widget(select2::classname(),     [ 'data' => arrayhelper::map(user::find()->all(),'id','username'),         'options' =>             ['placeholder' => 'select receivers...', 'multiple' => true],         'pluginoptions' =>             [ 'tags' => true,                 'maximuminputlength' => 10             ],     ]); ?> 

in view seems correctly, in textfield receivers appear 1 one, when press "send" button says receiver id must integer. how can solve issue? need duplicate 1 db record different receivers select using select2 dropdown list. example, choose in dropdownlist user1 , user2, "send" action should work twice accordingly. in db table named 'letter' should 2 same records different id , receiver_id.

my actioncreate function in controller class:

public function actioncreate() {     $model = new letter();      if ($model->load(yii::$app->request->post())) {          foreach($model->receiver_id $r_id){             $save = new letter();             $save->type_id = $model->type_id;             $save->subject = $model->subject;             $save->body = $model->body;             $save->sender_id = $model->sender_id;             $save->start_date = $model->start_date;             $save->end_date = $model->end_date;             $save->receiver_id = $r_id;             $save->save();         }         $model->attachment = uploadedfile::getinstance($model, 'attachment');         $filename = pathinfo($model->attachment , pathinfo_filename);         $ext = pathinfo($model->attachment , pathinfo_extension);          $newfname = $filename.'.'.$ext;          $path=yii::getalias('@webroot').'/uploads/';         if(!empty($newfname)){             $model->attachment->saveas($path.$newfname);             $model->attachment = $newfname;             if($model->save()){                 return $this->redirect(['view', 'id' => $model->id]);             }         }     }     return $this->render('create', [         'model' => $model,     ]);  } 

my ide says on "$model->receiver_id" "expected types array or object, actual: int"

thanks in advance.

do receiver_id array on model; ,

foreach($model->receiver_id $r_id){     $save = new yourmodel();     $save->yourproperty = $model->yourproperty;     ....     $save->receiver_id = $r_id;     $save->save(); }