XMLHttpRequest not receiving response

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Hi there I am currently using a file uploader on my website to upload files to my database. Before the file is uploaded I need to carry out some validation that can only be done server side as it needs to access the database. The uploader is using XMLHttpRequest and my application uses ASP.Net web forms. The problem is that if the validation fails server side and an error is returned the response is not received client side. It works correctly if the file is uploaded or even if the validation is carried out after the file is uploaded. Anyway below is a simple example of what im doing.

Javascript

JavaScript

var xhr = this._xhrs[id] = new XMLHttpRequest();

xhr.onreadystatechange = function () {
  if (xhr.readyState == 4) {
    self._onComplete(id, xhr);
  }
};

xhr.open("POST", queryString, true);
xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest");
xhr.setRequestHeader("X-File-Name", encodeURIComponent(name));
xhr.setRequestHeader("Content-Type", "application/octet-stream");
xhr.send(file);

VB

Sub ProcessRequest(ByVal context As HttpContext) Implements HttpHandler.ProcessRequest
  Dim fileName As String = context.Request.QueryString("qqfile")

  if Not Database.IsValid(fileName) then
  begin
    context.Response.Write("{error:""Invalid file""}")
    Return
  end If

  Dim newFile As New FileStream(strPath + "\" + fileName, FileMode.Create)
  Dim body As Byte() = context.Request.BinaryRead(context.Request.TotalBytes)
  newFile.Write(body, 0, body.Length)
  newFile.Flush()
  newFile.Close()  
  context.Response.Write("{success: true}")

End Sub

Posted 26-Sep-11 2:56am

TimWatson123

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Comments

Yuri Vital 26-Sep-11 9:30am

You are listening readyState == 4 only ...
Have tried to see what happen on ReadyState =3 ?

Have you seen what append during the client/server communication, capturing packet with Fiddler (http://www.fiddler2.com/fiddler2/) ?

TimWatson123 26-Sep-11 9:46am

I dont receive a readyState == 3 when returning the error before I have uploaded the file, only after I have uploaded the file. But I do receive a readyState == 1 and the status is [Exception: DOMException]. Any ideas why?

Yuri Vital 26-Sep-11 9:58am

readyState == 1 mean "Connection Open" see here : http://www.w3.org/TR/XMLHttpRequest/#event-handler-attributes

Have you tried to reply simply : {success: false}
???

TimWatson123 26-Sep-11 10:17am

Yeah ive tried that, it didnt work.

If I call Request.TotalBytes before returning the error code it works. The only problem is that TotalBytes hangs until the full file has been uploaded to the server. For some reason I only receive readyStates 1 and 4 when returning before uploading. I think this is my main problem:

"responseText of type DOMString
If the readyState attribute has a value other than 3 (Receiving) or 4 (Loaded), it must be the empty string. Otherwise, it must be the the body of the data received so far, interpreted using the character encoding specified in the response, or UTF-8 if no character encoding was specified. Invalid bytes must be converted to U+FFFD REPLACEMENT CHARACTER."
http://www.w3.org/TR/2006/WD-XMLHttpRequest-20060405/#dfn-readystate

Am I trying to set the response text when the readyState is not 3 or 4? If so is there a way of causing the readyState to change to 3 or 4 server side before setting the response text?

2 solutions

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sunasara Imdadhusen · Answer 1 · 2011-09-26T19:06:00

Solution 1

You may take help from following:

Lightweight Image Upload with Animation[^]

Posted 26-Sep-11 19:06pm

Sunasara Imdadhusen

submarelime · Answer 2 · 2019-09-24T22:07:00

if you are on Windows you can post your XMLHTTPRequest in the Export Folder that's found in the Windows System32 directory under inserv....Every time the computer shuts down anything that is in that Export file is "picked up" and received by ...iis or winremotemgmt team using that folder as a back door to collect your collectibles...faxes, etc.

XMLHttpRequest not receiving response

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XMLHttpRequest not receiving response

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