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Using AJAX.NET how do you clear an uploadfile control?

Posted on 2011-02-15
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Last Modified: 2012-06-27
I have a regular upload file control inside an AJAX.NET updatepanel.  If I use it to upload a file once, its no problem; however, if i hit the submit button again, even though the text box is clear, it is still attached to the previous file uploaded.

How do I clear that so that I may use the uploadfile control freshly?
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Question by:RichardRiga
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Kamal Khaleefa earned 250 total points
ID: 34904109
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Author Comment

by:RichardRiga
ID: 34910571
That's a neat article but how do I call a javascript function after the .NET webservice code has completed its work?
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Expert Comment

by:Kamal Khaleefa
ID: 34914764
regarding to Ur  question
but a JavaScript function to see if the file upload is empty

 var FileUpload1="<%=FileUpload1.ClientID %>"
function CheckForTestFile()
   {
        var file = document.getElementById(FileUpload1);
        var fileName=file.value;        
        //Checking for file browsed or not
        if (Trim(fileName) =='' )
        {
            alert("Please select a file to upload!!!");
            file.focus();
            return false;
        }
 }
and on ur button
add this

 <asp:Button ID="btnUpload" runat="server"  OnClientClick="if(CheckForTestFile()){return true}else{return false}"
                                                  text="Upload File" TabIndex="50" EnableViewState="False" />
                                           
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Author Comment

by:RichardRiga
ID: 34916726
These methods don't seem to work still.  I have inserted them into the proper places and they are being executed; however, the fileupload control still reports that it has contents when trying to upload a blank file'
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Author Comment

by:RichardRiga
ID: 34917036
My apologies!!  I completely forgot to mention that I wasn't using an ASP:FileUpload control.  I'm using the AsyncFileUpload control from the AjaxToolkit.  I'm not sure it makes a difference in your answers;however, I should have added that.
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Assisted Solution

by:CodeCruiser
CodeCruiser earned 250 total points
ID: 34917067
>however, the fileupload control still reports that it has contents when trying to upload a blank file'
Do you mean you are uploading a 0 byte file?
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Author Comment

by:RichardRiga
ID: 34918554
Here is what happens:

1.  I use the control to upload a file.  That works, no problem.  
     At this point the control's field resets itself to appear empty.
     Since the field is empty, at this point, if I hit the submit button again, the property fuFileUpload.HasFile should be False.  But its not.  It returns true.

2.  So i use a script:
            function clearContents() {
                 var AsyncFileUpload = $get("<%=fuFileUpload.ClientID%>");
                 var txts = AsyncFileUpload.getElementsByTagName("input");
                 for (var i = 0; i < txts.length; i++) {
                     if (txts[i].type == "text") {
                         txts[i].value = "";
                         txts[i].style.backgroundColor = "white";
                     }
                 }
             }

and call on that script when the file is uploaded with:
<cc1:AsyncFileUpload ID="fuFileUpload" runat="server" OnClientUploadComplete="<%UploadComplete() %>" />

Codebehind has:
    Public Sub CallUploadComplete()
        ClientScript.RegisterStartupScript(Me.GetType(), "removeDoc", "ClearContents()", True)
    End Sub

Something isn't right.  Can anyone fix those three snippets of code to make it work?  I beg!  
And thanks.

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Expert Comment

by:CodeCruiser
ID: 34924555
What does the

IsNothing(fuFileUpload.PostedFile)

return?
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Author Closing Comment

by:RichardRiga
ID: 35028696
Project was scrapped.  Apologies for the waste of time, but thank you for being respondent
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