title: React Ant Design multiple files upload doesn't work
body: <p>I'm in the process of sending multiple files from "React.js" by <code>formData.append()</code> to a backend.</p>
  
  <p>At the backend(Spring boot), I was able to see that multiple files were saved well with postman.</p>
  
  <p>The problem occurred in React.</p>
  
  <p>(I'm using "Ant Design" that is React UI Library.)</p>
  
  <p>Below is the source that append files to formdata with extra data.</p>
  
  <pre><code>const formData = new FormData();
  formData.append('webtoonId', this.state.selectedToonId);
  formData.append('epiTitle', this.state.epiTitle);
  formData.append('eFile', this.state.thumbnail[0].originFileObj);
  for( let i = 0; i&lt; this.state.mains.length ; i++){
      formData.append('mFiles', this.state.mains[i].originFileObj);
  }
  uploadEpi(formData)
  </code></pre>
  
  <p>uploadEpi() is POST API.</p>
  
  <p>Below is about state.</p>
  
  <pre><code>this.state = {
      toons: [],
      epiTitle :'',
      thumbnail : [],
      mains : [],
      selectedToonID : ''
  }
  </code></pre>
  
  <p>When I submit, Text and single file are stored in the DB normally, but only multiple files cannot be saved.</p>
  
  <p>There was no error. Just multiple files didn't be saved.</p>
  
  <p>The state "mains" is configured as shown below.<br/>
  <a href="https://i.stack.imgur.com/LltTF.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LltTF.png" alt="enter image description here"></a></p>
  
  <p><br/>
  <br/>
  I guess it's because I'm using Ant Design incorrectly.<Br/>
  (Ant Design : <a href="https://ant.design/components/upload/" rel="nofollow noreferrer">https://ant.design/components/upload/</a>) 
  <br/>
  <br/></p>
  
  <p>Why I guessed so, because when I add <code>multiple</code> attribute to <code>&lt;Dragger&gt;</code> like below,</p>
  
  <pre><code>&lt;Dragger onChange={this.onChangeMain} beforeUpload={() =&gt; false} multiple={true}&gt;
  </code></pre>
  
  <p>the state "mains" multiple files became <code>undefined</code>.</p>
  
  <p>Below is <code>onChange={this.onChangeMain}</code></p>
  
  <pre><code>onChangeMain=({ fileList })=&gt; {
      this.setState({ mains : fileList }, function(){
          console.log(this.state)
      });
  }
  </code></pre>
  
  <p><br/>
  <br/></p>
  
  <p>The bottom line is, I want to know how to upload multiple files through <code>&lt;Upload&gt;</code> (or <code>&lt;Dragger&gt;</code>) in "React Ant Design."</p>
  
  <p><br/>
  I don't know what should I do.<br/>
  <br/>
  this is my github about this project.<br/>
  <br/>
  I'd appreciate with your help. thx.</p>