USE KARTIK GRIDVIEW CHECKBOX COLUMN AND RETRIEVE DATA FROM SELECTED ROWS

Here is a reference for this extension: http://demos.krajee.com/grid

View file:

<?=Html::beginForm(['controller/bulk'],'post');?>
<?=Html::dropDownList('action','',[''=>'Mark selected as: ','c'=>'Confirmed','nc'=>'No Confirmed'],['class'=>'dropdown',])?>
<?=Html::submitButton('Send', ['class' => 'btn btn-info',]);?>
<?=GridView::widget([
'dataProvider' => $dataProvider,
'columns' => [
['class' => 'yii\grid\CheckboxColumn'],
'id',
],
]); ?>
<?= Html::endForm();?> 

Controller:

public function actionBulk(){
    $action=Yii::$app->request->post('action');
    $selection=(array)Yii::$app->request->post('selection');//typecasting
    foreach($selection as $id){
        $e=Evento::findOne((int)$id);//make a typecasting
        //do your stuff
        $e->save();
    }
    }

Source: https://stackoverflow.com/questions/28992972/yii2-how-to-properly-create-checkbox-column-in-gridview-for-bulk-actions