MemoryStream到HttpResponseMessage

Question

I have generated a Pdf on the server, and need to return it as a response to my web client, so that I get a 'Save As' dialog.

The pdf is generated, and saved to a Memory stream... which is then returned to my method which will return the HttpResponseMessage.

The is the method:

[Route("GeneratePdf"), HttpPost]
public HttpResponseMessage GeneratePdf(PlateTemplateExtendedDto data)
{

    var doc = GeneratePdf(DataForThePdf);

    //using (var file = File.OpenWrite("c:\\temp\\test.pdf"))
    //    doc.CopyTo(file); // no need for manual stream copy and buffers

    HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.OK);

    byte[] buffer = new byte[0];
    //get buffer
    buffer = doc.GetBuffer();
    //content length for use in header
    var contentLength = buffer.Length;

    response.Headers.AcceptRanges.Add("bytes");
    response.StatusCode = HttpStatusCode.OK;
    response.Content = new StreamContent(doc);
    response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("render");
    response.Content.Headers.ContentDisposition.FileName = "yes.pdf";
    response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
    response.Content.Headers.ContentLength = doc.Length;

    return response;
}

However, the document renders as a blank file, and although it has a file size, and properties of the document I created (pdf information if File Properties is all right, as well as page width and height), the document displays as blank.

If I un-comment the code that is commented out, to save locally, the file is perfect. File size is 228,889 bytes. However, when I let it go to my web page and save it, it's 405,153 bytes and the filename is 'undefined'.

If I breakpoint, I see these results:

On the front end script, I handle the downloaded object like this:

$.post("/api/PlateTemplate/GeneratePdf", data).done(function (data, status, headers) {

            // headers = headers();

            var filename = headers['x-filename'];
            var contentType = headers['content-type'];
            //Create a url to the blob
            var blob = new Blob([data], { type: contentType });
            var url = window.URL.createObjectURL(blob);
            var linkElement = document.createElement('a');
            linkElement.setAttribute('href', url);
            linkElement.setAttribute("download", filename);

            //Force a download
            var clickEvent = new MouseEvent("click", {
                "view": window,
                "bubbles": true,
                "cancelable": false
            });
            linkElement.dispatchEvent(clickEvent);
        });

I'm unsure where the file is being corrupted. What am I doing wrong?

Edit: Using the following code as suggested:

$.post("/api/PlateTemplate/GeneratePdf", data).done(function (data, status, headers) {
            alert(data.length);

            var xhr = new XMLHttpRequest();

            $("#pdfviewer").attr("src", URL.createObjectURL(new Blob([data], {
                type: "application/pdf"
            })))

.Net code:

var doc = GeneratePdf(pdfParams);

            HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.OK);

            byte[] buffer = new byte[0];
            //get buffer
            buffer = doc.ToArray();
            //content length for use in header
            var contentLength = buffer.Length;

            response.Headers.AcceptRanges.Add("bytes");
            response.StatusCode = HttpStatusCode.OK;
            response.Content = new StreamContent(doc);
            response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("render");
            response.Content.Headers.ContentDisposition.FileName = "yes.pdf";
            response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
            response.Content.Headers.ContentLength = doc.Length;

            return response;

It seems I am losing data. The alert is the length of the 'data.length' in my javascript, after I get data back from the call. The file properties is the original pdf file info.

File sends from api, size is 227,564, which matches the byte size on disk if I save it. So it SEEMS the sending is OK. But on the javascript size, when I read in the file, it's 424946, when I do: var file = new Blob([data], { type: 'application/pdf' }); (Where data is the response from the server).

Answer 1

The ContentLength setting looks somewhat suspicious (not consequent):

       //content length for use in header
        var contentLength = buffer.Length;
        response.Content.Headers.ContentLength = doc.Length;

Answer 2

我使用从.Net控制器到javascript Web api调用结果的base64编码的字符串“修复”了该问题，然后允许浏览器通过指定类型（'application / pdf'）将其转换为二进制。