Need some idea about upload a file using ajax - asp.net

Question

i want to upload an image on my host in my aspx page.but can i do that with ajax?(i mean,no postback done during the upload).
i look at the gmail file uploader,the classic mode used flax(this is bad idea) but i can understand about the modern mode?!!
according to my search in Google it is impossible for security reasons may be occure
some body help me about this issue."upload a file using ajax"

Answer 1

you can do like this.. using ajax .....
STEP 1: first create an upload form in separate page which is like this (myIframe.html)
<form method="POST" target="_self" enctype="multipart/form-data" action="main.aspx">
<input type="file" name="fileUpload" />
<input type="submit" value="UPLOAD" />
</form>
STEP 2: In main page (main.aspx), you have to put an iframe and loaded that page in it. you can also made borders invisible so it did not look like it is an iframe.
<iframe name="iUploadFrame" src="myIframe.html" frameborder="0" onload="iUploadFrameLoad();"></iframe>
Note that this is specifying onload event handler function of javascript. that one will explain it below.
STEP 3: For testing, in main.aspx and in UpdatePanel with a button and label like this:
<asp:UpdatePanel ID="pnlMain" runat="server">
<ContentTemplate>
<asp:Label id="lblMessage" runat="server" />
<asp:Button id="btnUploadComplted" runat="server" style="visibility:hidden;" />
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="btnUploadCompleted" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
Note that if you want you can hide the button using CSS style, but not setting visible=”False” attribute. This is because if you want to have the button html in the output document and would want to trigger the ajax callback via that button.
STEP 4: you can define the click event hander of the button in the codebehind like this :
protected void btnUploadCompleted_Click(object s, EventArgs e) {
lblMessage.Text = "UPLOAD PROCESS COMPLETED SUCCESSFULLY";
}
STEP :5 Now, to save file you can do write the code in the code-behind like this:
protected void Page_Load(object s, EventArgs e) {
if ((Request.Files.Count == 1)) {
// process to save file
Response.Write("SUCCESS");
Response.End();
}
}
STEP:6 Now all that we need to do is create javascript function to integrate the process into ajax implementation. The event will trigger when upload process is complete, and it will, in turn, triggers btnUploadCompleted’s click event, which is responsible for making our ajax call.
<script type="text/javascript">
function iUploadFrameLoad() {
if (window.iUploadFrame.document.body.innerHTML == "SUCCESS") {
document.forms[0].elements[btnUploadCompleted].click();
}
}
</script>
I hope it will helps you...