c# - AsyncFileUpload postback causes double upload -

i implemented asyncfileupload control on web page. web page requires uploaded files appear in gridview.
gridview contains following columns: "file name", "confidential" check box, , "remove" button remove uploaded file.

since asyncfileupload postback not full page postback, need "force" postback on onclientuploadcomplete event of asyncfileupload control in order render gridview after uploading file.
in onclientuploadcompleteevent, use javascript call __dopostback. in postback, bind gridview , display file information (i don’t re-save file).

the problem: on asyncfileupload’s first “partial” postback, file uploaded, expected. on second postback force __dopostback, file re-uploaded.
can verify using google chrome, displays upload progress. behaviour follows:
- after selecting file, progress increments 0% 100% , file uploaded.
- after this, __dopostback executes, , can see upload progress increment again 0% 100%.

how can make sure gridview populated, file not uploaded twice?

i attached sample solution contains issue: https://www.yousendit.com/download/mzzfc2zbndrryun4dnc9pq

maybe ugly, works:

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1) add css-hidden asp:button bellow asp:asyncfileupload asyncfileupload1 control.

<asp:button runat="server" id="btnclick" text="update grid" style="display:none"/> 

2) on page_load method, remove if (request.params.get("__eventtarget") == "uploadpostback") , put block in simple else previous if.

3) on asyncfileupload1_uploadedcomplete function, remove if (request.params.get("__eventtarget") != "uploadpostback") line, leave intact inside it.

4) aspx. put asp:updatepanel outside grid gridview1.

<asp:updatepanel runat="server" updatemode="conditional">      <triggers>          <asp:asyncpostbacktrigger controlid="btnclick" eventname="click" />      </triggers>      <contenttemplate>       <asp:gridview id="gridview1" ...      grid code remains same      </asp:gridview>      </contenttemplate> </asp:updatepanel> 

5) last step change ajaxuploadcomplete client-side javascript function make trigger postback. replace following:

function ajaxuploadcomplete() {     var btnclick = document.getelementbyid("btnclick");     btnclick.click(); } 

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any file user selects uploaded once.
changes here meant made in ajaxupload.aspx & ajaxupload.aspx.cs of ajaxupload.zip.