Download multiple files from Azure blob storage as zip file

Question

I try to download multiple files from a web API in .NET Core 3.1 and put them in a zip archive written in the response body. When I download the zip file with the browser the zip file is corrupted!

Controller :

public async Task DownloadFilesAsync([FromServices] IFileService fileService, [FromBody] IEnumerable<Guid> fileIds, Guid folderId)
{
    HttpContext.Response.Headers.Add("Content-Disposition", $"{DispositionTypeNames.Attachment};filename*=files.zip");
    HttpContext.Response.ContentType = MediaTypeNames.Application.Zip;
    await fileService.GetZipAsync(User.UserId(), folderId, fileIds, HttpContext.Response.Body);
}

Service :

public async Task GetZipAsync(Guid userId, Guid folderId, IEnumerable<Guid> fileIds, Stream stream)
{
    using (ZipArchive zip = new ZipArchive(stream, ZipArchiveMode.Create, leaveOpen: true))
    {
        foreach (Guid id in fileIds)
        {
            // metadata stored in a sql database, File is a custom type
            File file = await _fileRepository.GetFileAsync(folderId, id);
            using Stream entry = zip.CreateEntry(file.Name, CompressionLevel.Optimal).Open();
            await _fileStorage.WriteBlobAsync(userId, folderId, file.Name, entry);
        }
    }
}

Storage repository :

public async Task WriteBlobAsync(Guid userId, Guid folderId, string name, Stream output)
{
    BlobContainerClient container = Client.GetBlobContainerClient(userId.ToString());
    await container.GetBlobClient($"{folderId}/{name}").DownloadToAsync(output);
}

But the downloaded zip archive is unusable:

What have I done wrong?

For those who pass by here, the code above is perfectly functional. see the accepted answer below... — Shadam, Aug 31 '22 at 10:41

score 0 · Accepted Answer · answered May 28 '21 at 07:44

0

Ok, I'm feeling myself a little stupid on this one...

This code is perfectly good on the back side, my problem was on the client side.

It was missing a { responseType: 'arraybuffer' } on my axios request configuration...

answered May 28 '21 at 07:44

Shadam

1,041
13
25

Jason Pan · Answer 2 · 2021-05-25T04:22:50.070

-1

Method 1.

You can try to dispose ZipArchive And error should be solved.

public async Task GetZipAsync(Guid userId, Guid folderId, IEnumerable<Guid> fileIds, Stream stream)
{
    using (ZipArchive zip = new ZipArchive(stream, ZipArchiveMode.Create, leaveOpen: true))
    {
        foreach (Guid id in fileIds)
        {
            // metadata stored in a sql database, File is a custom type
            File file = await _fileRepository.GetFileAsync(folderId, id);
            using Stream entry = zip.CreateEntry(file.Name, CompressionLevel.Optimal).Open();
            await _fileStorage.WriteBlobAsync(userId, folderId, file.Name, entry);
        }
        //I added this line 
        zip.Dispose();
    }
}

Method 2.

You can set the stream's AutoFlush property to true.

For more details, you can refer below link.

ZipArchive gives Unexpected end of data corrupted error

edited May 25 '21 at 04:22

answered May 25 '21 at 04:10

Jason Pan

15,263
1
14
29

2

Huh? `using` automatically calls `Dispose`. How would disposing of `zip` twice help? – Zer0 May 25 '21 at 04:12
@Zer0 Sorry, I add wrong place. I have updated, try it. – Jason Pan May 25 '21 at 04:12
That's still a double dispose. That line doesn't need to exist. That's what the `using` keyword does. – Zer0 May 25 '21 at 04:14
@Zer0 https://stackoverflow.com/questions/47707862/ziparchive-gives-unexpected-end-of-data-corrupted-error/47707973 – Jason Pan May 25 '21 at 04:17
Pick a solution from another thread is not a good practice, I already searched across sof and don't found any working solution. The linked post has already been tested without any success. And as say @Zer0 `Dispose()` twice the ZipArchive has no reason to be done – Shadam May 26 '21 at 16:05

Download multiple files from Azure blob storage as zip file

2 Answers2