Adding filter to GridView widget

Question

I am trying to add filter to GridView widget included in _form.php. The grid is showing fine, even filter field is shown, but the filter is not working.

Here is my code:

<?php  
   $searchModel = New CitySearch(); ?>


    <?= GridView::widget([
        'dataProvider' => $dataProvider,
        'filterModel' => $searchModel,
        'columns' => [
            ['class' => 'yii\grid\SerialColumn'],

          //  'id',
            'city_name',

            ['class' => 'yii\grid\ActionColumn'],
        ],
    ]); ?>   

Solution

I have found the solution. The search model must actually be searched before attaching it to the GridView. Therefore, I just needed to add one line to get it to work:

$dataProvider = $searchModel->search(Yii::$app->request->queryParams);

The entire code would like like that:

<?php  
   $searchModel = New CitySearch(); 
   $dataProvider = $searchModel->search(Yii::$app->request->queryParams);
?>


<?= GridView::widget([
        'dataProvider' => $dataProvider,
        'filterModel' => $searchModel,
        'columns' => [
            ['class' => 'yii\grid\SerialColumn'],

          //  'id',
            'city_name',

            ['class' => 'yii\grid\ActionColumn'],
        ],
    ]); ?>