Returning memorystream - gives corrupt PDF file or "cannot accessed a closed stream"

c#, itext, pdf, stream

Solution

Reuse of streams can be problematic, especially if you are using an abstraction and you don't quite know what it is doing to your stream. Because of this I generally recommend never passing streams themselves around. If you can by with it, try just passing the raw underlying byte array itself. But if passing streams is a requirement then I recommend still doing the raw byte array at the end and then wrapping that in a new second stream. Try the below code to see if it works.

public Stream Generate(GiftModel model)
{
    //We'll dump our PDF into these when done
    Byte[] bytes;

    using (var ms = new MemoryStream())
    {
        using (var doc = new Document())
        {
            using (var writer = PdfWriter.GetInstance(doc, ms))
            {
                doc.Open();
                doc.Add(new Paragraph("Hello"));
                doc.Close();
            }
        }
        //Finalize the contents of the stream into an array
        bytes = ms.ToArray();
    }
    //Return a new stream wrapped around our array
    return new MemoryStream(bytes);
}

Problem

I have a web service, which calls the following method. I want to return a memorystream, which is a PDF file. Now, the problem is the PDF file is corrupt with the following code. I think it's because the files are not being closed. However, if I close them, I get the classic error "Cannot access a closed stream". When I previously saved it through a filestream, the PDF file wasn't corrupt. So my humble question is: How to solve it and get back a non-corrupt PDF file? :-) My code: ``` public Stream Generate(GiftModel model) { var template = HttpContext.Current.Server.MapPath(TemplatePath); // Magic code which creates a new PDF file from the stream of the other PdfReader reader = new PdfReader(template); Rectangle size = reader.GetPageSizeWithRotation(1); Document document = new Document(size); MemoryStream fs = new MemoryStream(); PdfWriter writer = PdfWriter.GetInstance(document, fs); document.Open(); // Two products on every page int bookNumber = 0; int pagesWeNeed = (int)Math.Ceiling(((double)model.Books.Count / (double)2)); for (var i = 0; i < pagesWeNeed; i++) { PdfContentByte cb = writer.DirectContent; // Creates a new page PdfImportedPage page = writer.GetImportedPage(reader, 1); cb.AddTemplate(page, 0, 0); // Add text strings DrawGreetingMessages(model.FromName, model.ReceiverName, model.GiftMessage, cb); // Draw the books DrawBooksOnPage(model.Books.Skip(bookNumber).Take(2).ToList(), cb); // Draw boring shit DrawFormalities(true, model.GiftLink, cb); bookNumber += 2; } // Close off our streams because we can //document.Close(); //writer.Close(); reader.Close(); fs.Position = 0; return fs; } ```

Original source