Creating Zip Files from Memory Stream C#

Question

Basically the user should be able to click on one link and download multiple pdf files. But the Catch is I cannot create files on server or anywhere. Everything has to be in mem

Answer 1

This link describes how to create a zip from a MemoryStream using SharpZipLib: https://github.com/icsharpcode/SharpZipLib/wiki/Zip-Samples#wiki-anchorMemory. Using this and iTextSharp, I was able to zip multiple PDF files that were created in memory.

Here is my code:

MemoryStream outputMemStream = new MemoryStream();
ZipOutputStream zipStream = new ZipOutputStream(outputMemStream);

zipStream.SetLevel(3); //0-9, 9 being the highest level of compression
byte[] bytes = null;

// loops through the PDFs I need to create
foreach (var record in records)
{
    var newEntry = new ZipEntry("test" + i + ".pdf");
    newEntry.DateTime = DateTime.Now;

    zipStream.PutNextEntry(newEntry);

    bytes = CreatePDF(++i);

    MemoryStream inStream = new MemoryStream(bytes);
    StreamUtils.Copy(inStream, zipStream, new byte[4096]);
    inStream.Close();
    zipStream.CloseEntry();
}

zipStream.IsStreamOwner = false;    // False stops the Close also Closing the underlying stream.
zipStream.Close();          // Must finish the ZipOutputStream before using outputMemStream.

outputMemStream.Position = 0;

return File(outputMemStream.ToArray(), "application/octet-stream", "reports.zip");

The CreatePDF Method:

private static byte[] CreatePDF(int i)
{
    byte[] bytes = null;
    using (MemoryStream ms = new MemoryStream())
    {
        Document document = new Document(PageSize.A4, 25, 25, 30, 30);
        PdfWriter writer = PdfWriter.GetInstance(document, ms);
        document.Open();
        document.Add(new Paragraph("Hello World " + i));
        document.Close();
        writer.Close();
        bytes = ms.ToArray();
    }

    return bytes;
}