Streaming In Memory Word Document using OpenXML SDK w/ASP.NET results in “corrupt” document

Question

I am unable to stream a word document that I create on the fly down to the browser. I am constantly getting a message from Microsoft Word that the document is corrupt.

Answer 1

First of all, always include Content-Length. If browser does not know the length of the http response body, then the connection remains opened (keep-alive). If there is no other way, save content to temp file (with delete on close option), and then get the content length.

Second, the document processing IN-MEM does not work for all options (for example, you cannot insert chunk into the document. You must use file mode).

Below is the sample for aspnet core :

[HttpPost]
public async Task<ActionResult<MopedResponse>> PostAsync(IFormCollection collection)
{

    string pathTemp = Path.GetTempFileName(); // get the temp file name

    // create or process the word file

    // reopen it for serving

    FileStream merged = new FileStream(pathTemp, FileMode.Open, FileAccess.Read, FileShare.None, 4096, FileOptions.DeleteOnClose);

    System.Net.Mime.ContentDisposition cd = new System.Net.Mime.ContentDisposition
    {
        FileName = "parafa.docx",
        Inline = true  // false = prompt the user for downloading;  true = browser to try to show the file inline
    };
    Response.Headers.Add("Content-Disposition", cd.ToString());
    Response.Headers.Add("Content-Length", merged.Length.ToString());

    return File(merged, "application/vnd.openxmlformats-officedocument.wordprocessingml.document", "mywordFile1.docx");

}