Question

I see that using JSON.Net, I can decode polymorphic objects if a $type attribute specifies the specific type of the JSON object. In all the examples I’ve seen, $type includes the namespace. Is it possible to make this work including just a simple type name without the assembly? I’d be happy to specify a default assembly to the JsonSerializer if that’s possible.

I am able to deserialize the JSON using:

public class SingleAssemblyJsonTypeBinder : SerializationBinder
{
    private readonly Assembly _assembly;
    private Dictionary<string, Type> _typesBySimpleName = new Dictionary<string, Type>(StringComparer.OrdinalIgnoreCase); 
    private Dictionary<Type,string> _simpleNameByType = new Dictionary<Type, string>(); 

    public SingleAssemblyJsonTypeBinder(Assembly assembly)
    {
        _assembly = assembly;
        _typesBySimpleName = new Dictionary<string, Type>();

        foreach (var type in _assembly.GetTypes().Where(t => t.IsPublic))
        {
            if (_typesBySimpleName.ContainsKey(type.Name))
                throw new InvalidOperationException("Cannot user PolymorphicBinder on a namespace where multiple public types have same name.");

            _typesBySimpleName[type.Name] = type;
            _simpleNameByType[type] = type.Name;
        }
    }

    public override Type BindToType(string assemblyName, string typeName)
    {
        Type result;
        if (_typesBySimpleName.TryGetValue(typeName.Trim(), out result))
            return result;

        return null;
    }

    public override void BindToName(Type serializedType, out string assemblyName, out string typeName)
    {
        string name;

        if (_simpleNameByType.TryGetValue(serializedType, out name))
        {
            typeName = name;
            assemblyName = null;// _assembly.FullName;
        }
        else
        {
            typeName = null;
            assemblyName = null;
        }
    }
}

…

public static JsonSerializerSettings GetJsonSerializationSettings()
{
    var settings = new JsonSerializerSettings();
    settings.Binder = new SingleAssemblyJsonTypeBinder(typeof(MvcApplication).Assembly);
    settings.TypeNameHandling = TypeNameHandling.Objects;
    return settings;
}

…

var serializer = JsonSerializer.Create(settings);

I haven’t been able to make this work with MVC though. I’m configuring JSON deserialization per the code below in Application_Start, and the object is deserialized, but using the base type one.

GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.Binder = new SingleAssemblyJsonTypeBinder(this.GetType().Assembly);
GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.TypeNameHandling = TypeNameHandling.All;
GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.TypeNameAssemblyFormat = FormatterAssemblyStyle.Simple;

Answer 1

Create a derived SerializationBinder in which override BindToName and Set out string assemblyName to null (Edit: or your default assembly name) and out string typeName to your striped type name

Set the binder to the JsonSerializerSettings.Binder before serialisation.

Let me know if this is not working