.net core create on memory zipfile

Question

I am working on an MVC project where I create dynamically pdf files(wkhtmltopdf) which I want to return in a zip file. The pdf files are generated on fly - I don't need to store them, so my code to return a single file is:

File(pdfBytes, "application/pdf", "file_name")

Taking a look on Microsoft docs their example goes through stored files:

 string startPath = @"c:\example\start";
 string zipPath = @"c:\example\result.zip";
 string extractPath = @"c:\example\extract";

 ZipFile.CreateFromDirectory(startPath, zipPath);
 ZipFile.ExtractToDirectory(zipPath, extractPath);

In my case I want to create N pdf files and return it to the view as a zip.. Something like:

ZipFile zip = new ZipFile();
foreach(var html in foundRawHTML)
{
//create pdf

//append pdf to zip
}

return zip;

Although this is not doable because:

1. ZipFile and File are statics and cannot be instatiated
2. There is no way to add a file into a zip on fly(in memory)

Any help is welcome

Answer 1

You can use in memory byte arrays and ZipArchive from System.IO.Compression, there is no need to map the local drive:

    public static byte[] GetZipArchive(List<InMemoryFile> files)
        {
            byte[] archiveFile;
            using (var archiveStream = new MemoryStream())
            {
                using (var archive = new ZipArchive(archiveStream, ZipArchiveMode.Create, true))
                {
                    foreach (var file in files)
                    {
                        var zipArchiveEntry = archive.CreateEntry(file.FileName, CompressionLevel.Fastest);
                        using (var zipStream = zipArchiveEntry.Open())
                            zipStream.Write(file.Content, 0, file.Content.Length);
                    }
                }

                archiveFile = archiveStream.ToArray();
            }

            return archiveFile;
        }

public class InMemoryFile
    {
        public string FileName { get; set; }
        public byte[] Content { get; set; }
    }