Question

I really like the ExpandoObject while compiling a server-side dynamic object at runtime, but I am having trouble flattening this thing out during JSON serialization. First, I instantiate the object:

dynamic expando = new ExpandoObject();
var d = expando as IDictionary<string, object>;
expando.Add("SomeProp", SomeValueOrClass);

So far so good. In my MVC controller, I want to then send this down as a JsonResult, so I do this:

return new JsonResult(expando);

This serializes the JSON into the below, to be consumed by the browser:

[{"Key":"SomeProp", "Value": SomeValueOrClass}]

BUT, what I’d really like is to see this:

{SomeProp: SomeValueOrClass}

I know I can achieve this if I use dynamic instead of ExpandoObject — JsonResult is able to serialize the dynamic properties and values into a single object (with no Key or Value business), but the reason I need to use ExpandoObject is because I don’t know all of the properties I want on the object until runtime, and as far as I know, I cannot dynamically add a property to a dynamic without using an ExpandoObject.

I may have to sift through the “Key”, “Value” business in my javascript, but I was hoping to figure this out prior to sending it to the client. Thanks for your help!

Answer 1

You could also, make a special JSONConverter that works only for ExpandoObject and then register it in an instance of JavaScriptSerializer. This way you could serialize arrays of expando,combinations of expando objects and … until you find another kind of object that is not getting serialized correctly(“the way u want”), then you make another Converter, or add another type to this one. Hope this helps.

using System.Web.Script.Serialization;    
public class ExpandoJSONConverter : JavaScriptConverter
{
    public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
    {
        throw new NotImplementedException();
    }
    public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
    {         
        var result = new Dictionary<string, object>();
        var dictionary = obj as IDictionary<string, object>;
        foreach (var item in dictionary)
            result.Add(item.Key, item.Value);
        return result;
    }
    public override IEnumerable<Type> SupportedTypes
    {
        get 
        { 
              return new ReadOnlyCollection<Type>(new Type[] { typeof(System.Dynamic.ExpandoObject) });
        }
    }
}

Using converter

var serializer = new JavaScriptSerializer(); 
serializer.RegisterConverters(new JavaScriptConverter[] { new ExpandoJSONConverter()});
var json = serializer.Serialize(obj);