GridView 搜索框 Select2

['attribute' => 'username',
    'filter' =>
        \kartik\select2\Select2::widget([
            'name' => 'MemberUserSearch[username]',
            'value' => Yii::$app->request->get('MemberUserSearch')['username'],
            'attribute' => 'state_2',
            'data' => $list,
            'options' => ['placeholder' => Yii::t('common', 'select')],
            'pluginOptions' => [
                'allowClear' => true,
                'width' =>'150px',

            ],
        ]),
],