title: Can not send Multiple choices from select2 with fromdata to upload file
body: <p>I have html select2,it can selected multiple option:</p>
  
  <pre><code>&lt;div class="form-group"&gt;
      &lt;label class="col-sm-1 control-label no-padding-right" for="form-field-recipient"&gt;Recipient:&lt;/label&gt;
      &lt;div class="col-sm-6 col-xs-12"&gt;
          &lt;span class="input-icon block col-xs-12 no-padding"&gt;
              &lt;select name="for" id="for" class="for" multiple="multiple" placeholder="For" style="width: 92%"&gt;
              &lt;?php
                  foreach($this-&gt;forList as $dataFor){ 
                  ?&gt;
                      &lt;option value="&lt;?php echo $dataFor['ohp_id'];?&gt;"&gt;&lt;?php echo $dataFor['title'];?&gt; Of &lt;?php echo $dataFor['name'];?&gt;&lt;/option&gt;
              &lt;?php } ?&gt;
              &lt;?php
                  foreach($this-&gt;group as $group){ 
                  ?&gt;
                      &lt;option value="&lt;?php echo $group['object_group_id'];?&gt;"&gt;&lt;?php echo $group['object_group_name'];?&gt;&lt;/option&gt;
              &lt;?php } ?&gt;
              &lt;/select&gt;
              &lt;i class="ace-icon fa fa-user col-xs-0"&gt;&lt;/i&gt;
          &lt;/span&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  
  $(document).ready(function() {
      $(".refnd").select2({placeholder: "Reference ND"});
      $(".for").select2({placeholder: "For"});
  </code></pre>
  
  <p>And this jquery:<br><br></p>
  
  <p><a href="https://i.stack.imgur.com/mNxoU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mNxoU.png" alt="enter image description here"></a></p>
  
  <p><br><br>
  But in PHP,it just show 1 option selected. How To fix it?</p>