select2 kartik yii2 posting null value issue

Question

I am using Kartik Select2 widget in yii2 , I've used the widget in my view and i have defined the array to show in the select to dropdown list , but when i select some of the items and post the form , it always posts null value to my controller . here is my ActiveForm in my view :

<?php
$form = ActiveForm::begin([
  'options' => ['enctype' => 'multipart/form-data'],
]);
?>

<?= $form->field($model,'title')->textinput(); ?>
<?= $form->field($model,'blog')->textarea(); ?>
<?= $form->field($model,'imageFile')->fileinput(); ?>

<?=
$form->field($model, 'tag')->widget(Select2::classname(), [
  'data' => $tags,
  'options' => ['placeholder' => '...تگ ها را انتخاب کنید'],
  'pluginOptions' => [
    'allowClear' => true,
    'multiple' => true,
  ],
]);
?>

<?= Html::SubmitButton('ارسال',['class' => 'btn btn-success green']); ?>

<?php ActiveForm::end(); ?>

And here is my controller which when i check the value posted from select2 widget with var_dump it is always null :

public function actionInsertBlog()
  {    
    $model = new Blog();
    $tagModel = new Tag();

    if ($model->load(Yii::$app->request->post())) {
      var_dump($model->tag);
      die();
      if ($model->insertBlog()) {
        Yii::$app->response->redirect('?r=blog/index',301)->send();
      } else {
        Yii::$app->response->redirect('?r=blog/insert-blog',301)->send();
      }
    } else {
      $tags = ArrayHelper::map($tagModel->find()->asArray()->all(),'id','tag');
      return $this->render('insert',['model' => $model , 'tagModel' => $tagModel , 'tags' => $tags]);
    }
  }

Answer 1

If you are getting null value in your controller, then main reason is model rules. According to rule load function set the attribute of model that exist in model rules , May be tag attribute does not exist in your model rule. That's why it is coming null, place "tag attribute as safe in rules"

[['tag'], 'safe'],