Response received from POST corrupted

Question

I have a service called DownloadZipFile that collates data and then builds a Zip file for it to be downloaded. this service returns a response containing the stream to the file

Service:

[HttpPost]
public ActionResult DownloadZipFile(string zipData)
{
    try
    {
        // Create the Zip File.
        using (MemoryStream zipStream = DownloadHelper.BuildZipFileData(zipData))
        {
            // Build up the reponse including the file.
            HttpContext.Response.ClearContent();
            HttpContext.Response.ClearHeaders();
            HttpContext.Response.Clear();
            HttpContext.Response.Buffer = true;
            HttpContext.Response.ContentType = "application/zip";
            HttpContext.Response.AddHeader("Content-Disposition", "attachment; filename=MyZipFile.zip;");
            HttpContext.Response.BinaryWrite(zipStream.ToArray());
            HttpContext.Response.End();
        }
    }
    catch (Exception e)
    {
        // Log the error.
        _logService.Error(LogHelper.GetWebRequestInfo(ControllerContext.HttpContext.Request), e);
    }
 }

It would download and open the zip file correctly if I call the service like this.

Service Call #1

var form = $("<form></form>").attr('action', "DownloadZipFile").attr("method", "post");
form.append($("<input></input>").attr("type", "hidden").attr("name", "zipData").attr('value', escape(JSON.stringify(zipData))));
form.appendTo('body').submit().remove();

However, if I use an AJAX Post call when converting it from response to blob, the size is much larger than what I sent.

Service Call #2:

$.post("DownloadZipFile", { zipData: escape(JSON.stringify(zipData)) },
     function (data, status, response) {
         var filename = "";
         var disposition = response.getResponseHeader('Content-Disposition');
         if (disposition && disposition.indexOf('attachment') !== -1) {
             var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/;
             var matches = filenameRegex.exec(disposition);
             if (matches != null && matches[1]) filename = matches[1].replace(/['"]/g, '');
         }

         var type = response.getResponseHeader('Content-Type');
         var blob = new Blob([data], { type: type });

         if (typeof window.navigator.msSaveBlob !== 'undefined') {
             window.navigator.msSaveBlob(blob, filename);
         } else {
             var URL = window.URL || window.webkitURL;
             var downloadUrl = URL.createObjectURL(blob);
             if (filename) {
                 var a = document.createElement("a");
                 if (typeof a.download === 'undefined') {
                     window.location = downloadUrl;
                 } else {
                     a.href = downloadUrl;
                     a.download = filename;
                     document.body.appendChild(a);
                     a.click();
                 }
             } else {
                 window.location = downloadUrl;
             }
         }
     });

Using Service Call #2 the Zip File I get is corrupted

Could it be the encoding? I checked the data between the correct and incorrect Zip Files and they look like this:

Correct Zip:

PK ú‚ÐJmÇ´¸g € BOM.csvu‘ËNÃ0E÷HüÃÈ+ÆÑØy/›”WÔðH[Ä64IÕ¦|>‰_ÀN(-¢l®,Ýã;wìÏ÷‡m^Ö³ú 35VkUŽtÕf6)óºZcZjqz"0dÒ³ü9TÓ%yd#ˆ3Ö˜R›¡kÙMYæt2'Òâ¦É½dÈhO¶"BXÁ?ùÚ”Ç<‰,ÖÍ ‘ååÎé ÁÝ!Ò ²AˆVG ]3

Corrupted Zip:

PK ￿￿￿g ￿ BOM.csvu￿￿￿E￿￿+￿￿/￿￿W￿H[￿4Iզ|>￿_￿(-￿l￿,￿;w￿￿￿m^ֳ￿kU￿t￿6)￿Zjqz"0dҳ￿yd#￿3֘R￿￿k￿MY￿2'￿￿ɽd￿O￿"BX￿￿￿,￿ ￿￿￿￿￿￿￿A￿VG ]3

It seems that the files were encoded differently. What do you guys think?

Answer 1

Thank you Musa for giving me that clue.

Now here is the Service Call I am using to download my Zip File:

Service Call #1

    var xhrq = new XMLHttpRequest();
    xhrq.onreadystatechange = function () {
        if (this.readyState == 4 ) {
            if (this.status == 200) {
                var xhrp = this;
                var response = this.response;

                // check for a filename
                var filename = "";
                var disposition = xhrp.getResponseHeader('Content-Disposition');
                if (disposition && disposition.indexOf('attachment') !== -1) {
                    var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/;
                    var matches = filenameRegex.exec(disposition);
                    if (matches != null && matches[1]) filename = matches[1].replace(/['"]/g, '');
                }

                var type = xhrp.getResponseHeader('Content-Type');
                var blob = new Blob([response], { type: type, encoding: "UTF-8" });

                if (typeof window.navigator.msSaveBlob !== 'undefined') {
                    window.navigator.msSaveBlob(blob, filename);
                } else {
                    var URL = window.URL || window.webkitURL;
                    var downloadUrl = URL.createObjectURL(blob);

                    if (filename) {
                        var a = document.createElement("a");
                        if (typeof a.download === 'undefined') {
                            window.location = downloadUrl;
                        } else {
                            a.href = downloadUrl;
                            a.download = filename;
                            document.body.appendChild(a);
                            a.click();
                        }
                    } else {
                        window.location = downloadUrl;
                    }
                    setTimeout(function () { URL.revokeObjectURL(downloadUrl); }, 100); // cleanup
                }
            } else {

   // Call Back for Error
            }
        }
    }

    // Open HTTP Request and Call API Function
    xhrq.open("POST", appPath + "DownloadZipFile");
    xhrq.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
    xhrq.responseType = 'blob';
    xhrq.send('designData=' + escape(JSON.stringify(zipData)));