Yii: drop down to choose page size for CGridView

drop-down-page-size-cgrid-view.php

// in config/main.php
	'params'     => array(
		'defaultPageSize' => 20,
	),

// in controller action
	public function actionIndex()
	{
		if ( isset( $_GET[ 'pageSize' ] ) )
		{
			Yii::app()->user->setState( 'pageSize', (int) $_GET[ 'pageSize' ] );
			unset( $_GET[ 'pageSize' ] );
		}

		$model = new MyModel( 'search' );
		$model->unsetAttributes();

		if ( isset( $_GET[ 'MyModel' ] ) )
			$model->attributes = $_GET[ 'MyModel' ];

		$this->render( 'index', array( 'model' => $model ) );
	}

// in model
	public function search()
	{
		$criteria = new CDbCriteria;
		$criteria->compare( 'product_code', $this->product_code );
		$criteria->compare( 'product_name', $this->product_name, true );
		$criteria->compare( 'product_price', $this->product_price, true );
		$criteria->compare( 'request_time', $this->request_time, true );
		$criteria->order = 'request_time DESC, product_code';

		return new CActiveDataProvider( $this, array(
			'criteria'   => $criteria,
			'pagination' => array(
				'pageSize' => Yii::app()->user->getState( 'pageSize', Yii::app()->params[ 'defaultPageSize' ] ),
			),
		) );
	}

// in index.php view
<p>
	<?php
	$pageSize = Yii::app()->user->getState( 'pageSize', Yii::app()->params[ 'defaultPageSize' ] );
	$pageSizeDropDown = CHtml::dropDownList(
		'pageSize',
		$pageSize,
		array( 10 => 10, 25 => 25, 50 => 50, 100 => 100 ),
		array(
			'class'    => 'change-pagesize',
			'onchange' => "$.fn.yiiGridView.update('grid-view-id',{data:{pageSize:$(this).val()}});",
		)
	);
	?>

<div class="page-size-wrap">
	<span>Display by:</span><?= $pageSizeDropDown; ?>
</div>

<?php Yii::app()->clientScript->registerCss( 'initPageSizeCSS', '.page-size-wrap{text-align: right;}' ); ?>

<?php
$this->widget( 'zii.widgets.grid.CGridView', array(
	'id'           => 'grid-view-id',
	'dataProvider' => $model->search(),
	'filter'       => $model,
	'summaryText'  => '{start} - {end} / {count}',
	'columns'      => array(
		array( 'name' => 'product_code' ),
		array( 'name' => 'product_name' ),
		array( 'name' => 'product_price' ),
		array( 'name' => 'request_time', 'filter' => false ),
	),
) );