public class MultiPartMediaTypeFormatter : MediaTypeFormatter
{
    ...
}

        public MultiPartMediaTypeFormatter()
        {
            SupportedMediaTypes.Add(new MediaTypeHeaderValue("multipart/form-data"));
        }

    public interface INeedMultiPartMediaTypeFormatter
    {
    }

public class NewProduct : INeedMultiPartMediaTypeFormatter
{
 ...
}

        public override bool CanReadType(Type type)
        {
            return typeof(INeedMultiPartMediaTypeFormatter).IsAssignableFrom(type);
        }

        public override bool CanWriteType(Type type)
        {
            return false;
        }

public async override Task<object> ReadFromStreamAsync(Type type, Stream stream, HttpContent content, IFormatterLogger formatterLogger)

            MultipartMemoryStreamProvider provider = await content.ReadAsMultipartAsync();
            IEnumerable<HttpContent> formData = provider.Contents.AsEnumerable();

            var modelInstance = Activator.CreateInstance(type);
            IEnumerable<PropertyInfo> properties = type.GetProperties();

            foreach (PropertyInfo prop in properties)
            {
                var propName = prop.Name.ToLower();
                var propType = prop.PropertyType;

                var data = formData.FirstOrDefault(d => d.Headers.ContentDisposition.Name.ToLower().Contains(propName));

                if (data != null)
                {
                    if (data.Headers.ContentType != null)
                    {
                        using (var fileStream = await data.ReadAsStreamAsync())
                        {
                            using (MemoryStream ms = new MemoryStream())
                            {
                                fileStream.CopyTo(ms);
                                prop.SetValue(modelInstance, ms.ToArray());
                            }                            
                        }
                    }

                if (data != null)
                {
                    if (data.Headers.ContentType != null)
                    {
                        //...
                    }
                    else
                    {
                        string rawVal = await data.ReadAsStringAsync();
                        object val = Convert.ChangeType(rawVal, propType);

                        prop.SetValue(modelInstance, val);
                    }
                }

return modelInstance;

config.Formatters.Add(new MultiPartMediaTypeFormatter());

class PirateName {
  ...
  String get jsonString => JSON.encode({"f": _firstName, "a": _appellation});
}

final String TREASURE_KEY = 'pirateName';

void main() {
  ...
}

void setBadgeName(PirateName newName) {
  if (newName == null) {
    return;
  }
  querySelector('#badgeName').text = newName.pirateName;
  window.localStorage[TREASURE_KEY] = newName.jsonString;
}

void setBadgeName(PirateName newName) {
  ...
}

PirateName getBadgeNameFromStorage() {
  String storedName = window.localStorage[TREASURE_KEY];
  if (storedName != null) {
    return new PirateName.fromJSON(storedName);
  } else {
    return null;
  }
}

void main() {
  ...
  setBadgeName(getBadgeNameFromStorage());
}

{ "names": [ "Anne", "Bette", "Cate", "Dawn",
        "Elise", "Faye", "Ginger", "Harriot",
        "Izzy", "Jane", "Kaye", "Liz",
        "Maria", "Nell", "Olive", "Pat",
        "Queenie", "Rae", "Sal", "Tam",
        "Uma", "Violet", "Wilma", "Xana",
        "Yvonne", "Zelda",
        "Abe", "Billy", "Caleb", "Davie",
        "Eb", "Frank", "Gabe", "House",
        "Icarus", "Jack", "Kurt", "Larry",
        "Mike", "Nolan", "Oliver", "Pat",
        "Quib", "Roy", "Sal", "Tom",
        "Ube", "Val", "Walt", "Xavier",
        "Yvan", "Zeb"],
  "appellations": [ "Awesome", "Captain",
        "Even", "Fighter", "Great", "Hearty",
        "Jackal", "King", "Lord",
        "Mighty", "Noble", "Old", "Powerful",
        "Quick", "Red", "Stalwart", "Tank",
        "Ultimate", "Vicious", "Wily", "aXe", "Young",
        "Brave", "Eager",
        "Kind", "Sandy",
        "Xeric", "Yellow", "Zesty"]}

...
  <div>
    <input type="text" id="inputName" maxlength="15" disabled>
  </div>
  <div>
    <button id="generateButton" disabled>Aye! Gimme a name!</button>
  </div>
...

import 'dart:html';
import 'dart:math' show Random;
import 'dart:convert' show JSON;

import 'dart:async' show Future;

class PirateName {
  ...
  static List<String> names = [];
  static List<String> appellations = [];
  ...
}

class PirateName {
  ...

  static Future readyThePirates() {
    var path = 'piratenames.json';
    return HttpRequest.getString(path)
        .then(_parsePirateNamesFromJSON);
  }
  
  static _parsePirateNamesFromJSON(String jsonString) {
    Map pirateNames = JSON.decode(jsonString);
    names = pirateNames['names'];
    appellations = pirateNames['appellations'];
  }
}

SpanElement badgeNameElement;

void main() {
  ...
}

void main() {
  InputElement inputField = querySelector('#inputName');
  inputField.onInput.listen(updateBadge);
  genButton = querySelector('#generateButton');
  genButton.onClick.listen(generateBadge);
  
  badgeNameElement = querySelector('#badgeName');
  ...
}

void main() {
  ...
  
  PirateName.readyThePirates()
    .then((_) {
      //on success
      inputField.disabled = false; //enable
      genButton.disabled = false;  //enable
      setBadgeName(getBadgeNameFromStorage());
    })
    .catchError((arrr) {
      print('Error initializing pirate names: $arrr');
      badgeNameElement.text = 'Arrr! No names.';
    });
}