iTextSharp creating file in memory resulting corrupted file - asp.net-mvc

Question

I am trying to create a pdf file in MVC using iTextSharp. I do have a following simple used case. File is getting created but when I open the PDF I am getting error file is corrupted unable to open the file. Any idea/help ?
My Controller code is a follows
public FileStreamResult GetPdfMemory()
{
iTextSharp.text.Document doc = new iTextSharp.text.Document();
MemoryStream mem = new MemoryStream();
PdfWriter pdfWriter = PdfWriter.GetInstance(doc, mem);
//pdfWriter.CloseStream = false;
doc.Open();
doc.Add(new Paragraph("Charts"));
mem.Position = 0;
FileStreamResult fileStreamResult = new FileStreamResult(mem, System.Net.Mime.MediaTypeNames.Application.Pdf)
{
FileDownloadName = "chart_" + ".PDF"
};
return fileStreamResult;
}
View :
#Html.ActionLink("Pdf Memory", "GetPdfMemory", "Home", null, new { id = "download"})
FYI : When I try to use FileStream instead of MemoryStream all works fine. But I need to create PDF using memorystream.

Answer 1

You manipulate (mem.Position = 0) and use (new FileStreamResult(mem, ...)) the MemoryStream before signalling iTextSharp that it can finalize the document. Thus, depending on whether implicit destruction of the Document and the PdfWriter or the use of the data in the memory stream comes first, you either have a PDF missing its closing parts or the closing parts (being written after you reposition the memory stream) overwriting the start of the data.
To signal to iTextSharp that it can finalize the document, please call doc.Close() before manipulating the memory stream or alternatively use the Document in a using block, e.g.:
using (MemoryStream ms = new MemoryStream()) {
// step 1
using (Document document = new Document()) {
// step 2
PdfWriter.GetInstance(document, ms);
// step 3
document.Open();
// step 4
document.Add(new Paragraph("HelloWorldMemory"));
}
HttpContext.Current.Response.BinaryWrite(ms.ToArray());
}
(shamelessly copied from the sample HelloWorldMemory.cs from the Webified iTextSharp Examples) for iText in Action — 2nd Edition)
Using using implicitly causes the Document to be closed.