view.php (buttons)

    <p>
        <?= Html::a('Edit', ['update', 'id' => $model->id], [
            'id' => 'edit-link',
            'onClick' =>"$('#view').find('.modal-body').load($(this).attr('href')); return false;",
            'class' => 'btn btn-primary'
        ]) ?>
        <?= Html::a(Yii::t('app', 'Delete'), ['delete', 'id' => $model->id], [
            'id' => 'delete',
            'class' => 'btn btn-danger',
            'data' => [
                'confirm' => Yii::t('app', 'Are you sure you want to delete this item?'),
                'method' => 'post',
            ],
        ]) ?>
    </p>