use kartik\export\ExportMenu;
use kartik\grid\GridView;
use kartik\helpers\Html;
$customDropdown = [
    'options' => ['tag' => false], 
    'linkOptions' => ['class' => 'dropdown-item']
];
$fullExportMenu = ExportMenu::widget([
    'dataProvider' => $dataProvider,
    'columns' => $gridColumns,
    'target' => ExportMenu::TARGET_BLANK,
    'asDropdown' => false, // this is important for this case so we just need to get a HTML list    
    'dropdownOptions' => [
        'label' => '<i class="fas fa-external-link-alt"></i> Full'
    ],
    'exportConfig' => [ // set styling for your custom dropdown list items
        ExportMenu::FORMAT_CSV => $customDropdown,
        ExportMenu::FORMAT_TEXT => $customDropdown,
        ExportMenu::FORMAT_HTML => $customDropdown,
        ExportMenu::FORMAT_PDF => $customDropdown,
        ExportMenu::FORMAT_EXCEL => $customDropdown,
        ExportMenu::FORMAT_EXCEL_X => $customDropdown,
    ],
]);
echo GridView::widget([
    'dataProvider' => $dataProvider,
    'columns' => $gridColumns,
    'panel' => [
        'type' => GridView::TYPE_PRIMARY,
        'heading' => '<h3 class="panel-title"><i class="fas fa-book"></i> Library</h3>',
    ],
    'exportContainer' => [
        'class' => 'btn-group mr-2 me-2'
    ],
    // the toolbar setting is default
    'toolbar' => [
        '{export}',
        ['content'=>
            Html::button('<i class="fas fa-plus"></i>', ['type'=>'button', 'title'=>Yii::t('kvgrid', 'Add Book'), 'class'=>'btn btn-success', 'onclick'=>'alert("This will launch the book creation form.\n\nDisabled for this demo!");']) . ' '.
                Html::a('<i class="fas fa-redo"></i>', ['grid-demo'], ['data-pjax'=>0, 'class' => 'btn btn-outline-secondary btn-default', 'title'=>Yii::t('kvgrid', 'Reset Grid')])
        ],
    ],
    // configure your GRID inbuilt export dropdown to include additional items
    'export' => [
        'itemsAfter'=> [
            '<div role="presentation" class="dropdown-divider"></div>',
            '<div class="dropdown-header">Export All Data</div>',
            $fullExportMenu
        ]
    ],
]);

$gridColumns = [
    ['class' => 'kartik\grid\SerialColumn'],
    'id',
    'name',
    [
        'attribute'=>'author_id',
        'label'=>'Author',
        'vAlign'=>'middle',
        'width'=>'190px',
        'value'=>function ($model, $key, $index, $widget) { 
            return Html::a($model->author->name, '#', []);
        },
        'format'=>'raw'
    ],
    'color',
    'publish_date',
    'status',
    ['attribute'=>'buy_amount','format'=>['decimal',2], 'hAlign'=>'right', 'width'=>'110px'],
    ['attribute'=>'sell_amount','format'=>['decimal',2], 'hAlign'=>'right', 'width'=>'110px'],
    ['class' => 'kartik\grid\ActionColumn', 'urlCreator'=>function(){return '#';}]
];