echo FileInput::widget([
'name' => 'attachments[]',
'options'=>[
'multiple'=>true
],
'pluginOptions' => [
'initialPreview'=>[
Html::img("/images/moon.jpg", ['class'=>'file-preview-image', 'alt'=>'The Moon', 'title'=>'The Moon']),
Html::img("/images/earth.jpg", ['class'=>'file-preview-image', 'alt'=>'The Earth', 'title'=>'The Earth']),
],
'initialCaption'=>"Files..",
'overwriteInitial'=>false
]
]);