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How to Prevent Uploads

caution

RadUpload has been replaced by RadAsyncUpload, Telerik’s next-generation ASP.NET upload component. If you are considering Telerik’s Upload control for new development, check out the documentation of RadAsyncUpload or the control’s product page. If you are already using RadUpload in your projects, you may be interested in reading how easy the transition to RadAsyncUpload is and how you can benefit from it in this blog post. The official support for RadUpload has been discontinued in June 2013 (Q2’13), although it is still be available in the suite. We deeply believe that RadAsyncUpload can better serve your upload needs and we kindly ask you to transition to it to make sure you take advantage of its support and the new features we constantly add to it.

RadUpload (and any other control that uses <input type=file> HTML elements for file selection and upload) automatically uploads all selected files when the user performs a postback. To prevent the automatic upload that occurs on a postback (for example in response to the click of another button on the Web page), you must clear the selected files before the postback occurs.

The following example demonstrates this approach, using the OnClientSubmitting event handler.

note

The example below works only with LinkButton or other controls that use the __doPostBack function to initiate postback, such as DropDownList or CheckBox with AutoPostBack=true . It will not work with a regular ASP:Button . If you need to use ASP:Button , you must set its UseSubmitBehavior property to false .

<script type="text/javascript">
    function onClientSubmitting(progressManager, args)
    {
      var eventTarget = document.getElementById('**EVENTTARGET');
      if (eventTarget.value == '<%= ButtonCancel.UniqueID %>'
            || eventTarget.value == '<%= OtherButtonWhichShouldNotUploadFiles.UniqueID %>') {
          //Clear the file inputs
          var upload = $find("<%= RadUpload1.ClientID %>");

          var fileInputs = upload.getFileInputs();
          for (var i = 0; fileInputs.length > i; i++) {
              upload.clearFileInputAt(i);
          }
      }
  }

</script>

<telerik:radprogressmanager runat="server" id="RadProgressManager1" onclientsubmitting="onClientSubmitting" />
<telerik:radupload runat="server" id="RadUpload1" />
<asp:LinkButton runat="server" ID="ButtonUpload" Text="Upload" />
<asp:LinkButton runat="server" ID="ButtonCancel" Text="Cancel" />
<asp:LinkButton runat="server" ID="OtherButtonWhichShouldNotUploadFiles" Text="Other Button Which Should Not Upload Files" />

See Also