How to parse Json.NET polymorphic objects?

Question

I've written a web service that sends and returns json created with Json.NET. I've included typenames, which allows polymorphism. With a bit of hacking, I've got this working with a silverlight client, but I don't know how to make it work for javascript clients.

How can I parse this using javascript?

{
  "$type": "MyAssembly.Zoo, MyAssembly",
  "ID": 1,
  "Animals": [
    {
      "$type": "MyAssembly.Dog, MyAssembly",
      "LikesBones": true,
      "Name": "Fido"
    },
    {
      "$type": "MyAssembly.Cat, MyAssembly",
      "LikesMice": false,
      "Name": "Felix"
    }
  ]
}

Here are the c# classes:

public class Animal
{
    public string Name { get; set; }
}
public class Dog : Animal
{
    public bool LikesBones { get; set; }
}
public class Cat : Animal
{
    public bool LikesMice { get; set; }
}
public class Zoo
{
    public int ID { get; set; }
    private List<Animal> m_Animals = new List<Animal>();
    public List<Animal> Animals { get { return m_Animals; } set { m_Animals = value; } }
    public static void Test1()
    {
        Zoo z1 = new Zoo() { ID = 1 };
        z1.Animals.Add(new Dog() { Name = "Fido", LikesBones = true });
        z1.Animals.Add(new Cat() { Name = "Felix", LikesMice = false });
        var settings = new JsonSerializerSettings();
        settings.TypeNameHandling = TypeNameHandling.Objects;

        string s1 = JsonConvert.SerializeObject(z1, Formatting.Indented, settings);
        Debug.WriteLine(s1);

        var z2 = JsonConvert.DeserializeObject<Zoo>(s1, settings);
        foreach (Animal a in z2.Animals)
        {
            if (a is Dog)
                Debug.WriteLine(((Dog)a).LikesBones);
            else if (a is Cat)
                Debug.WriteLine (((Cat)a).LikesMice);
            else
                Debug.WriteLine("error");
        }

    }
}

Can you show your deserialization code in Silverlight? I'm curious how you got it to work. My attempts are not working so far. stackoverflow.com/questions/5943764/… — rboarman
– rboarman, Commented May 10, 2011 at 17:25

StriplingWarrior · Accepted Answer · 2011-05-10 17:16:52Z

3

To do the actual parsing, you can use json2.js or JQuery's $.parseJSON() method. Those will create a javascript object that directly resembles the JSON you sent across.

Since Javascript is a script language, you won't be thinking in terms of "polymorphism" anymore, but you should be able to evaluate properties on the objects (without caring what "type" of object they are) like so:

var obj = $.parseJSON(json);
var firstAnimalName = obj.Animals[0].Name;

answered May 10, 2011 at 17:16

StriplingWarrior

158k29 gold badges261 silver badges326 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

MattyC · Accepted Answer · 2011-05-10 17:00:56Z

0

Try https://github.com/douglascrockford/JSON-js/blob/master/json2.js. There is a parse function which will parse your string into a javascript object safely.

answered May 10, 2011 at 17:00

MattyC

2042 silver badges4 bronze badges

Collectives™ on Stack Overflow

How to parse Json.NET polymorphic objects?

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related