Upload/Download large files with ASP.NET Core 2.2

Question

I need to upload and downlods files above 2GB using ASP.NET Core 2.2, but I don’t know the best way to do this. For the download, to using the following method:

[HttpGet("id")]
public IActionResult Download(Guid id)
{
    // Recupero o caminho físico do arquivo com base no id aqui
    return PhysicalFile(path, MimeTypes.GetMimeType(path), Path.GetFileName(path));
}

Apparently it works normal, but I have doubts about performance or parallel requests. There is a better approach to doing this?

Already in the upload I thought of separating the file into pieces on the client side and sending these pieces in various requests. On the server side I would receive each piece, save at the end of the file and send a reply so that a new piece is sent. But... Is this really a good way to do it? I think I might have competition issues opening/closing the file at the written time.

What is the appropriate way to download/upload?

Answer 1

You can use a form with enctype Multipart/form-data. It supports large files, sending files is done by parts only which is managed by the browser.

I made a project available on Github with a Net Core project and the file upload progress bar to the server.

I left the simplified version of the code here.

In the case of Net Core you need to indicate the maximum size that your server accepts.

Program.Cs

public class Program
    {
        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .UseKestrel(options =>
                {
                    options.Limits.MaxRequestBodySize = 209715200;
                });
    }

Startup.Cs

    public void ConfigureServices(IServiceCollection services)
    {

         services.Configure<FormOptions>(x =>
        {
          x.MultipartBodyLengthLimit = 1209715200;
        });
    }

Front

    <form method="post" enctype="multipart/form-data" 
action="file" onsubmit="AJAXSubmit(this);return false;" >
            <input type="file" name="file"/>
            <input type="submit" value="Upload" />            
    </form>


    async function AJAXSubmit (form) {

    var formData = new FormData($(form)[0]);

    $.ajax({
        url: "file",
        type: 'POST',
        data: formData,
        async: true,
        success: function (data) {
            alert('Sent');
        },
        cache: false,
        contentType: false,
        processData: false
    });
   }

Backend

[HttpPost]
    [RequestFormLimits(MultipartBodyLengthLimit = 1209715200)]
    [RequestSizeLimit(1209715200)]
    public async Task<ActionResult> Post(IFormFile file)
    {
        FileStream filestream = new FileStream("/tmp/" + file.FileName, FileMode.Create, FileAccess.Write);

        using (var memoryStream = new MemoryStream())
        {
            await file.CopyToAsync(memoryStream);

            memoryStream.WriteTo(filestream);
        }

        return Ok(new { count = 1, file.FileName, file.Length});
    }