How to create zip file in memory?

Question

I have to create a zip file from set of urls. and it should have a proper folder structure. So i tried like

   public async Task<byte[]> CreateZip(Guid ownerId)
    {
        try
        {
            string startPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "zipFolder");//base folder
            if (Directory.Exists(startPath))
            {
                DeleteAllFiles(startPath);
                Directory.Delete(startPath);
            }
            Directory.CreateDirectory(startPath);

            string zipPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, $"{ownerId.ToString()}"); //folder based on ownerid
            if (Directory.Exists(zipPath))
            {
                DeleteAllFiles(zipPath);
                Directory.Delete(zipPath);
            }

            Directory.CreateDirectory(zipPath);
            var attachemnts = await ReadByOwnerId(ownerId);

            attachemnts.Data.ForEach(i =>
            {
                var fileLocalPath = $"{startPath}\\{i.Category}";
                if (!Directory.Exists(fileLocalPath))
                {
                    Directory.CreateDirectory(fileLocalPath);
                }
                using (var client = new WebClient())
                {
                    client.DownloadFile(i.Url, $"{fileLocalPath}//{i.Flags ?? ""}_{i.FileName}");
                }
            });
            var zipFilename = $"{zipPath}//result.zip";

            if (File.Exists(zipFilename))
            {
                File.Delete(zipFilename);
            }

            ZipFile.CreateFromDirectory(startPath, zipFilename, CompressionLevel.Fastest, true);


            var result = System.IO.File.ReadAllBytes(zipFilename);
            return result;
        }
        catch (Exception ex)
        {
            var a = ex;
            return null;
        }
    }

currently im writing all files in my base directory(may be not a good idea).corrently i have to manually delete all folders and files to avoid exception/unwanted files. Can everything be written in memory?

What changes required to write all files and folder structure in memory?

Is it the source files or the final ZIP file that you want in memory? To create the ZIP file you can use a `MemoryStream`; reference [here](https://learn.microsoft.com/en-us/dotnet/api/system.io.memorystream?view=netframework-4.8) — Peter Smith, Dec 30 '19 at 08:42
i want to create a source file/folder structure from urls, i want tht also in memory. you can see my foreach for creating folder. — hilda_sonica_vish, Dec 30 '19 at 08:54
I know of no way to create the folder structure in memory. Depending on your deployment environment can you create a temporary working folder on your server that is not in your application folder. We use such a thing frequently. — Peter Smith, Dec 30 '19 at 08:56
As @PeterSmith said I would create a temp work folder. Eg a new Guid, so something like: "/xxxx-xxxx-xxxx-xxxx/Folder-To-Zip/...." — Kiksen, Dec 30 '19 at 09:03
you can use the answer from [this question](https://stackoverflow.com/questions/29647570/how-to-create-ziparchive-from-files-in-memory-in-c). But you have to call `zipArchive.CreateEntry` with a dir name in front of file name, like `zipArchive.CreateEntry($"{startPath}\\{attachment.FileName}"` — oleksa, Dec 30 '19 at 09:10
what do you mean by "maintain" sorry? You can create zip entries (write files into zip archive) by using the `CreateEntry` method. However you can put folder names of entry is being created (path) like `CreateEntry("folderInZip\\subfolderInZip\\file.txt")`. This will create zip archive entry `file.txt` that is located in the `folderInZip\subfolderInZip` path. — oleksa, Dec 30 '19 at 09:51

score 1 · Answer 1 · answered Dec 30 '19 at 09:06

No you can't. Not with the built in Dotnet any way.

As per my comment I would recommend storing the files in a custom location based on a Guid or similar. Eg:

"/xxxx-xxxx-xxxx-xxxx/Folder-To-Zip/....".

This would ensure you could handle multiple requests with the same files or similar file / folder names.

Then you just have to cleanup and delete the folder again afterwards so you don't run out of space.

score 0 · Answer 2 · answered Dec 30 '19 at 11:07

Hope the below code does the job.

public async Task<byte[]> CreateZip(Guid ownerId)
        {
            try
            {
                string startPath = Path.Combine(Path.GetTempPath(), $"{Guid.NewGuid()}_zipFolder");//folder to add

                Directory.CreateDirectory(startPath);

                var attachemnts = await ReadByOwnerId(ownerId);
                attachemnts.Data = filterDuplicateAttachments(attachemnts.Data);
                //filtering youtube urls
                attachemnts.Data = attachemnts.Data.Where(i => !i.Flags.Equals("YoutubeUrl", StringComparison.OrdinalIgnoreCase)).ToList();

                attachemnts.Data.ForEach(i =>
                {
                    var fileLocalPath = $"{startPath}\\{i.Category}";
                    if (!Directory.Exists(fileLocalPath))
                    {
                        Directory.CreateDirectory(fileLocalPath);
                    }
                    using (var client = new WebClient())
                    {
                        client.DownloadFile(i.Url, $"{fileLocalPath}//{i.Flags ?? ""}_{i.FileName}");
                    }
                });

                using (var ms = new MemoryStream())
                {
                    using (var zipArchive = new ZipArchive(ms, ZipArchiveMode.Create, true))
                    {
                        System.IO.DirectoryInfo di = new DirectoryInfo(startPath);
                        var allFiles = di.GetFiles("",SearchOption.AllDirectories);
                        foreach (var attachment in allFiles)
                        {
                            var file = File.OpenRead(attachment.FullName);

                            var type = attachemnts.Data.Where(i => $"{ i.Flags ?? ""}_{ i.FileName}".Equals(attachment.Name, StringComparison.OrdinalIgnoreCase)).FirstOrDefault();
                            var entry = zipArchive.CreateEntry($"{type.Category}/{attachment.Name}", CompressionLevel.Fastest);
                            using (var entryStream = entry.Open())
                            {
                                file.CopyTo(entryStream);
                            }
                        }
                    }
                    var result = ms.ToArray();
                    return result;
                }
            }
            catch (Exception ex)
            {
                var a = ex;
                return null;
            }
        }

How to create zip file in memory?

2 Answers2