creating a zip file from an object directly without disk IO

Question

I am writing a REST API which will take in a JSON request object. The request object will have to be serialized to a file in JSON format; the file has to be compressed into a zip file and the ZIP file has to be posted to another service, for which I would have to deserialize the ZIP file. All this because the service I have to call expects me to post data as ZIP file. I am trying to see if I can avoid disk IO. Is there a way to directly convert the object into a byte array representing ZIP content in-memory instead of all the above steps?

Note : I'd prefer accomplishing this using .net framework libraries (as against external libraries)

Answer 1

Yes, it is possible to create a zip file completely on memory, here is an example using SharpZip Library (Update: A sample using ZipArchive added at the end):

public static void Main()
{
    var fileContent = Encoding.UTF8.GetBytes(
        @"{
            ""fruit"":""apple"",
            ""taste"":""yummy""
          }"
        );


    var zipStream = new MemoryStream();
    var zip = new ZipOutputStream(zipStream);

    AddEntry("file0.json", fileContent, zip); //first file
    AddEntry("file1.json", fileContent, zip); //second file (with same content)

    zip.Close();

    //only for testing to see if the zip file is valid!
    File.WriteAllBytes("test.zip", zipStream.ToArray());
}

private static void AddEntry(string fileName, byte[] fileContent, ZipOutputStream zip)
{
    var zipEntry = new ZipEntry(fileName) {DateTime = DateTime.Now, Size = fileContent.Length};
    zip.PutNextEntry(zipEntry);
    zip.Write(fileContent, 0, fileContent.Length);
    zip.CloseEntry();
}

You can obtain SharpZip using Nuget command PM> Install-Package SharpZipLib

Update:

Note : I'd prefer accomplishing this using .net framework libraries (as against external libraries)

Here is an example using Built-in ZipArchive from System.IO.Compression.Dll

public static void Main()
{
    var fileContent = Encoding.UTF8.GetBytes(
        @"{
            ""fruit"":""apple"",
            ""taste"":""yummy""
          }"
        );

    var zipContent = new MemoryStream();
    var archive = new ZipArchive(zipContent, ZipArchiveMode.Create);

    AddEntry("file1.json",fileContent,archive);
    AddEntry("file2.json",fileContent,archive); //second file (same content)

    archive.Dispose();

    File.WriteAllBytes("testa.zip",zipContent.ToArray());
}


private static void AddEntry(string fileName, byte[] fileContent,ZipArchive archive)
{
    var entry = archive.CreateEntry(fileName);
    using (var stream = entry.Open())
        stream.Write(fileContent, 0, fileContent.Length);

}