Extend GridView ActionColumn with additional icon

Question

I\'m building a webapp with Yii2 framework that will provide users (logged in) the capability to download pre-uploaded files by administrators.

I\'ve created the act

Answer 1

template attribute is important

echo GridView::widget([
    'dataProvider' => $dataProvider,
    'filterModel' => $searchModel,
    'columns' => [
        ['class' => 'yii\grid\SerialColumn'],
         'id', 
         'title',
        ['class' => 'yii\grid\ActionColumn',
            'buttons' => [
                'additional_icon' => function ($url, $model, $key) {
                    return Html::a ( ' ', ['controller/action', 'id' => $model->id] );
                },
            ],
            'template' => '{update} {view} {delete} {additional_icon}'


        ],
    ],
]);