title: am using dropzone in yii2 but i have error
body: <p>in form</p>
  <pre><code>&lt;?php 
            try {
              echo \kato\DropZone::widget([
                  'options' =&gt; [
                      'maxFilesize' =&gt; '10',
                      'url'         =&gt; yii::$app-&gt;urlManager-&gt;baseUrl.'/items/items/uploads' ,
                  ],
                  'clientEvents' =&gt; [
                      'complete' =&gt; &quot;function(file){console.log(file)}&quot;,
                      'removedfile' =&gt; &quot;function(file){alert(file.name + ' is removed')}&quot;
                  ],
              ]);
          } catch (Exception $e) {
          }
          ?&gt;
  </code></pre>
  <p>error display in console</p>
  <blockquote>
  <p>Uncaught Error: No URL provided.
  at new c (dropzone.min.js:1)
  at Function.a.discover (dropzone.min.js:1)
  at a._autoDiscoverFunction (dropzone.min.js:2)
  at HTMLDocument.f (dropzone.min.js:2)</p>
  </blockquote>
  <blockquote>
  <p>Uncaught Error: Dropzone already attached.
  at new c (dropzone.min.js:1)
  at HTMLDocument. (create:558)
  at mightThrow (jquery.js:3762)
  at process (jquery.js:3830)</p>
  </blockquote>