Multipart form data body is 0

[Petermarcu]

@Drakoumel opened this here: dotnet/core#805

Issue Title

The body of the receiving controller action of a multipart form data request is 0

General

So in short, I have two applications the FE and the API.
From the FE a user needs to upload a big file thus we use the code provided https://docs.microsoft.com/en-us/aspnet/core/mvc/models/file-uploads

Ajax -> FE -> API.
The Ajax to FE works fine, but the FE to API send 0 body length. Although their controllers use the exact same code from the ms link.

On the API receiving end I see the following (see exception)

I do not know why this happens.
'section.Body.ReadTimeout' threw an exception of type 'System.InvalidOperationException'

Following is the code I use.

FileStream targetStream = System.IO.File.Create(targetFilePath);                        
                        await section.Body.CopyToAsync(targetStream);
                        Console.WriteLine($"Copied the uploaded file '{targetFilePath}'");
                        
                        if (await _api.UploadFile(id, contentDisposition.FileName.Trim('"'), targetStream))
                        {
                            return BadRequest("Failed to upload file");
                        }

which on its own calls

Client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", _session.AuthenticationToken());

            Client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            MultipartFormDataContent form = new MultipartFormDataContent();

            HttpContent content = new StringContent("fileToUpload");
            form.Add(content, "fileToUpload");

            content = new StreamContent(stream);

            content.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
            {
                Name = "fileToUpload",
                FileName = fileName
            };
            form.Add(content);

Upon sending the stream has Body length.
But upon receiving on the API it is empty.

        [HttpPost("{id}")]
        [DisableFormValueModelBinding]
        public async Task<IActionResult> Upload()
        {
            string displayUrl = HttpContext.Request.GetDisplayUrl();
            var arrayUrl = displayUrl.Split('/');
            string metricId = arrayUrl.ToList().Last();

            if (!this.IsMultipartContentType(Request.ContentType))
            {
                return BadRequest($"Expected a multipart request, but got {Request.ContentType}");
            }

            string targetFilePath = null;

            var boundary = this.GetBoundary(
                MediaTypeHeaderValue.Parse(Request.ContentType),
                _defaultFormOptions.MultipartBoundaryLengthLimit);
            var reader = new MultipartReader(boundary, HttpContext.Request.Body);

            var section = await reader.ReadNextSectionAsync(); <-- section.body = 0
}

I also tried with postman, which generated the code bellow ( I dont know which format is best )

curl -X POST \
  http://localhost:5000/api/cloudstorage/08d4df1d-29a6-b421-9c77-df96f63c9f83 \
  -H 'authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..hgj-C2Z4-ZcP6mDd7wIm7AVyWF0EzZwbvP6BIVzMKMs' \
  -H 'cache-control: no-cache' \
  -H 'content-type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW' \
  -H 'postman-token: 03f0b075-654d-2164-5f7c-bf1fa3277deb' \
  -F 'file=@C:\Users\AAA\AppData\Local\Postman\app-5.1.2\content_resources_200_percent.pak'

[Tratcher]

Don't you need to rewind targetStream before calling UploadFile?

[MaximRouiller]

Let's do this old school.

[Eilon]

Closing this issue because it isn't clear to me if there is an issue remaining. If you feel there's still an issue, please re-open this issue or log a new issue with complete details of the problem. Thanks!