guild/backend/modules/document/views/template/_form.php

<?php

use kartik\file\FileInput;
use mihaildev\elfinder\InputFile;
use yii\helpers\Html;
use yii\widgets\ActiveForm;

/* @var $this yii\web\View */
/* @var $model backend\modules\document\models\Template */
/* @var $form yii\widgets\ActiveForm */
?>

<div class="template-form">

    <?php $form = ActiveForm::begin([
        'options' => ['enctype'=>'multipart/form-data']]); ?>

    <?= $form->field($model, 'title')->textInput(['maxlength' => true]) ?>

    <?= $form->field($model, 'template')->widget(FileInput::classname(), [
        'options' => ['accept' => 'text/*'],
        'pluginOptions' => [
                'allowedFileExtensions'=>['doc','docx','txt'],'showUpload' => true
        ],
    ]);   ?>

    <div class="form-group">
        <?= Html::submitButton('Сохранить', ['class' => 'btn btn-success']) ?>
    </div>

    <?php ActiveForm::end(); ?>

</div>