SharePoint - download folder as zip file

Question

I need an API (C#) to download folder as one zip file in SharePoint. This feature is enabled in SharePoint website after selecting one or a few folders but I can't find how to do this programmatically. I don't see something in class Microsoft.SharePoint.Client.Folder. Perhaps to use somehow Microsoft.SharePoint.Client.DocumentSet. Can't find an answer. I can do this file by file with using File.OpenBinaryDirect but maybe already exists ready function. Thanks.

Answer 1

Sample code for your reference.

static void Main(string[] args)
        {
            string _SiteUrl = "https://domain.sharepoint.com/sites/tst";
            using (var clientContext = new ClientContext(_SiteUrl))
            {
                Console.ForegroundColor = ConsoleColor.Green;
                string password = "pw";
                SecureString sec_pass = new SecureString();
                Array.ForEach(password.ToArray(), sec_pass.AppendChar);
                sec_pass.MakeReadOnly();
                clientContext.Credentials = new SharePointOnlineCredentials("lee@domain.onmicrosoft.com", sec_pass);

                Web web = clientContext.Web;
                Folder folder = web.GetFolderByServerRelativeUrl("/sites/TST/MyDoc4/Folder");
                var files = folder.Files;
                clientContext.Load(files);
                clientContext.ExecuteQuery();
                Console.WriteLine();
                //Regex regex = new Regex(_SiteUrl, RegexOptions.IgnoreCase);

                var list = web.Lists.GetByTitle("MyDoc4");
                var libRootFolder = list.RootFolder;
                var subFolder = libRootFolder.Folders.GetByUrl("Folder");
                clientContext.Load(libRootFolder);
                clientContext.Load(subFolder);
                clientContext.ExecuteQuery();
                Console.WriteLine(libRootFolder.ItemCount);
                Console.WriteLine(subFolder.ItemCount);


                using (System.IO.MemoryStream mStream = new System.IO.MemoryStream())
                {
                    using (var archive = new ZipArchive(mStream, ZipArchiveMode.Create, true))
                    {
                        foreach (var file in files)
                        {
                            clientContext.Load(file);
                            Console.WriteLine(file.Name);
                            ClientResult<Stream> stream = file.OpenBinaryStream();
                            clientContext.ExecuteQuery();

                            var zipArchiveEntry = archive.CreateEntry(file.Name);
                            using (Stream zipEntryStream = zipArchiveEntry.Open())
                            {

                                    if (stream != null)
                                    {
                                        stream.Value.CopyTo(zipEntryStream);
                                    }

                            }
                        }
                    }
                    using (var fileStream = new FileStream(@"C:\Lee\FileDownload\test.zip", FileMode.Create))
                    {
                        mStream.Seek(0, SeekOrigin.Begin);
                        mStream.CopyTo(fileStream);
                    }
                }


                Console.WriteLine("done");
                Console.ReadKey();
            }

        }