Consuming JSON From WPF

I want to throw up some prototype code that consumes JSON from WPF. (For more on JSON, see this article.) I put together that uses the JavaScriptSerializer to deserialize JSON into CLR objects, which could then be used for databinding. 

Here's what I did. First, I went and downloaded the ASP.NET AJAX framework.  Then, I created a new WPF project and added a reference the System.Web.Extensions dll, which got installed to C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET 2.0 AJAX Extensions.  I then added the System.Web.Script.Serialization to my using statements.

To keep things simple, I wanted to prove I could convert this JSON:

{ "FirstName": "Karsten", "IsAlive": "true"}

Into this CLR type:

class Person
{
    public string FirstName;
    public bool IsAlive;
}

Turned out to be pretty simple.  Here's the code:

public Window1()
{
    InitializeComponent();
    JavaScriptSerializer jss = new JavaScriptSerializer();
    jss.RegisterConverters(new JavaScriptConverter[] { 
    new PersonConverter() });
    string test = "{\"FirstName\": \"Karsten\", \"IsAlive\": \"true\"}";
    Person p = jss.Deserialize<Person>(test);
    Person p = jss.d
}

Note how I register this thing called the PersonConverter after I instantiate the JavaScriptSerializer .  That's where all the work gets done and I'll discuss the PersonConverter below.  The only other interesting thing to note here is that to get the Person object,  I use the Deserialize<> method instead of the DeserializeObject(). This allows me to actually pass the type I want to have returned rather than attempting to cast the object afterward.

So, here's the code for the PersonConverter, which overrides the JavaScriptConverter :

class PersonConverter : JavaScriptConverter
{

    public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
    {
        Person p = new Person();
        p.FirstName = serializer.ConvertToType<string>(dictionary["FirstName"]);
        p.IsAlive = serializer.ConvertToType<bool>(dictionary["IsAlive"]);
        return p;
    }
    public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
    {
        throw new Exception("The method or operation is not implemented.");
    }

    public override IEnumerable<Type> SupportedTypes
    {
        get { return new Type[] { typeof(Person)}; }
    }
}

The crux of the code here is in the override of Deserialize.  I followed the SDK documentation and made sure to use the ConvertToType method instead of doing the casting myself.  Basically, I just map each property from the JSON to the CLR object.  One could probably get fancy and use Reflection to do this dynamically, if you had everything singing.

I think I'll iterate on this a little more in a future post, but the net is that you can consume JSON into your WPF applications!