C#~memory multipart con campos de formulario , utilidad cargar archivos sin guardar en disco y acceder a formdata fields

Controller.cs

sing System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;
using System.Web.Http;

namespace WebApplication3.Controllers
{
    public class ValuesController : ApiController
    {
        // Ejemplo de uso de custom mmultipart provider
        [HttpPost, Route("api/image")]
        public async Task<IHttpActionResult> Images()
        {
            if (!Request.Content.IsMimeMultipartContent())
                throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);

            var provider = new MultipartFormMemoryProvider();
            await Request.Content.ReadAsMultipartAsync(provider);
            string result = "" + await Request.Content.ReadAsStringAsync();
            foreach (var file in provider.Contents)
            {
                result += file.Headers.ContentDisposition.FileName;
                    // var filename = file.Headers.ContentDisposition.FileName.Trim('\"');
                    var buffer = await file.ReadAsStringAsync();
                    //result += buffer;
                
                //Do whatever you want with filename and its binaray data.
            }
            string data = provider.FormData.GetValues("entidad").FirstOrDefault();
            result += data;
            return Ok(result);
        }
    }
}

MultipartFormMemoryProvider.cs

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;
using System.Web;

/**
 * Multipart form provider en memoria
 * Tratar imagenes en memoria
 * Acceder a campos de formData
 * */
namespace WebApplication3.Controllers
{
    public class MultipartFormMemoryProvider : MultipartMemoryStreamProvider
    {
        private readonly Collection<bool> _isFormData = new Collection<bool>();
        // Coleccion de los campos mapeados 
        private readonly NameValueCollection _formData = new NameValueCollection(StringComparer.OrdinalIgnoreCase);
           
        public NameValueCollection FormData
        {
            get { return _formData; }
        }

        public override Stream GetStream(HttpContent parent, HttpContentHeaders headers)
        {
            if (parent == null) throw new ArgumentNullException("parent");
            if (headers == null) throw new ArgumentNullException("headers");

            var contentDisposition = headers.ContentDisposition;

            if (contentDisposition != null)
            {
                _isFormData.Add(String.IsNullOrEmpty(contentDisposition.FileName));
                return base.GetStream(parent, headers);
            }

            throw new InvalidOperationException("Did not find required 'Content-Disposition' header field in MIME multipart body part.");
        }

        public override async Task ExecutePostProcessingAsync()
        {
            for (var index = 0; index < Contents.Count; index++)
            {
                if (IsStream(index))
                    continue;

                var formContent = Contents[index];
                var contentDisposition = formContent.Headers.ContentDisposition;
                var formFieldName = UnquoteToken(contentDisposition.Name) ?? string.Empty;
                var formFieldValue = await formContent.ReadAsStringAsync();
                FormData.Add(formFieldName, formFieldValue);
            }
        }

        private static string UnquoteToken(string token)
        {
            if (string.IsNullOrWhiteSpace(token))
                return token;

            if (token.StartsWith("\"", StringComparison.Ordinal) && token.EndsWith("\"", StringComparison.Ordinal) && token.Length > 1)
                return token.Substring(1, token.Length - 2);

            return token;
        }

        public bool IsStream(int idx)
        {
            return !_isFormData[idx];
        }
    }
}