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AsyncFileUpload postback causes double upload

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伪装坚强ぢ
伪装坚强ぢ 2020-12-07 02:32

I implemented the AsyncFileUpload control on a web page. This web page requires uploaded files to appear in a GridView.
The GridView

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6条回答
  • 栀梦
    2020-12-07 03:10

    I believe @Veera had it right. UploadComplete was being called multiple times as the file was uploading. The following worked for me.

    void AsyncFileUpload1_UploadedComplete(object sender, AsyncFileUploadEventArgs e) {
    if (AsyncFileUpload1.IsUploading) return;
    // rest of your upload code
}

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  • 眼角桃花
    2020-12-07 03:11

    AsyncFileUpload has a property that named IsUploading. when this property is set to false, a postback will happen. you can check this property like this:

    if(AsyncFileUpload1.IsUploading)
 {
  ..... upload codes
 }
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  • 感情败类
    2020-12-07 03:16

    I don't have access to your sample solution which contains the issue but i encounter a double postback too in my project with the AsyncFileUpload component. I found a very simple workaround :

    Just add: 

    private bool justUploaded = false;

    Then:

    void AsyncFileUpload1_UploadedComplete(object sender, AsyncFileUploadEventArgs e)
{
    if (justUploaded) return;
    justUploaded = true;
    // rest of your upload code
}
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  • 死守一世寂寞
    2020-12-07 03:18

    Maybe ugly, but works:

    1) Add a css-hidden asp:Button bellow the asp:AsyncFileUpload AsyncFileUpload1 control.

    <asp:Button runat="server" ID="btnClick" Text="Update grid" style="display:none"/>

    2) On the Page_Load method, remove the if (Request.Params.Get("__EVENTTARGET") == "UploadPostback") and put its block in a simple else to the previous if.

    3) On the AsyncFileUpload1_UploadedComplete function, also remove the if (Request.Params.Get("__EVENTTARGET") != "UploadPostback") line, but leave intact everything that was inside it.

    4) Back to the aspx. Put a asp:UpdatePanel outside the grid GridView1.

    <asp:UpdatePanel runat="server" UpdateMode="Conditional">
     <Triggers>
         <asp:AsyncPostBackTrigger ControlID="btnClick" EventName="Click" />
     </Triggers>
     <ContentTemplate>

     <asp:GridView ID="GridView1" ...
     YOUR GRID CODE REMAINS THE SAME
     </asp:GridView>

    </ContentTemplate>
</asp:UpdatePanel>

    5) The last step is to change the AjaxUploadComplete client-side javascript function to make it trigger the postback. Replace it with the following:

    function AjaxUploadComplete() {
    var btnClick = document.getElementById("btnClick");
    btnClick.click();
}

    Any file the user selects is uploaded only once.
    All changes here are meant to be made in AjaxUpload.aspx & AjaxUpload.aspx.cs of your AjaxUpload.zip.

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  • 慢半拍i
    2020-12-07 03:19

    I find this a more elegant solution, found here: http://forums.asp.net/t/1951566.aspx?AsyncFileUpload+uploads+twice) but below is my altered fully working code:

    <html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>AsyncFileUpload Example</title>
    <script type = "text/javascript">
        function uploadComplete(sender) {
            $get("<%=lblMesg.ClientID%>").innerHTML = "File Uploaded Successfully";
            clearContents();
        }


        function uploadError(sender) {
            $get("<%=lblMesg.ClientID%>").innerHTML = "File upload failed.";
            clearContents();
        }


    function clearContents() {
            var span = $get("<%=AsyncFileUpload1.ClientID%>");
            var txts = span.getElementsByTagName("input");
            for (var i = 0; i < txts.length; i++) {
                if (txts[i].type == "text") {
                    txts[i].value = "";
                }
                if (txts[i].type == "file") {
                    txts[i].value = "";
                }
            }
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
        <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <cc1:AsyncFileUpload OnClientUploadError="uploadError"
            OnClientUploadComplete="uploadComplete" runat="server"
            ID="AsyncFileUpload1" Width="400px" UploaderStyle="Modern" EnableViewState = "false"
            UploadingBackColor="#CCFFFF"  ThrobberID="imgLoader" OnUploadedComplete = "FileUploadComplete"
          />
        <asp:Image ID="imgLoader" runat="server" ImageUrl = "~/images/loader.gif" />
        <br />
       <asp:Label ID="lblMesg" runat="server" Text=""></asp:Label>






    </form>
</body>
</html>
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  • 被撕碎了的回忆
    2020-12-07 03:21

    There is a simpler solution

    @@t0x1n3Himself the solution u gave is very simple but does not work

    surround the AsyncFileUpload with an update panel name it UpdatePanelAFU then in the UpdatePanelAFU do as the following :

     protected void AsyncFileUpload_UpdatePanelAFU(object sender,AjaxControlToolkit.AsyncFileUploadEventArgs e)
{

    if (Request.Params.Get("__EVENTTARGET") != "UpdatePanelAFU")
        return;
..... rest of the code 
}

    enjoy!

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