asp.net core, accept file and form

action.cs

[HttpPost]
public async Task<IActionResult> Create([FromForm] UploadItem data)
{
    var files = Request.Form.Files;
    if (files.Count < 1) return BadRequest(new {message = nameof(Resource.NoFilesAttached)});
    await _svc.CreateAsync(files, data, User.GetUserId());
    return Ok();
}

UploadItem.cs

public class UploadItem
{
    [Required, Range(1, int.MaxValue)]
    public int DataSourceId { get; set; }
    public string Description { get; set; }
}

xhr.js

const formData = new FormData()
formData.append('datafile', file, file.name)
formData.append('DataSourceId', this.state.dataSourceId)
formData.append('Description', this.state.description)

const xhr = new XMLHttpRequest()
xhr.open('post', '/api/endpoint', true)
xhr.send(formData)