Just thought i would share a solution also based on this that works with the Knowntype attribute using reflection , had to get derived class from any base class, solution can benefit from recursion to find the best matching class though i didn't need it in my case, matching is done by the type given to the converter if it has KnownTypes it will scan them all until it matches a type that has all the properties inside the json string, first one to match will be chosen.
usage is as simple as:
string json = "{ Name:\"Something\", LastName:\"Otherthing\" }";
var ret = JsonConvert.DeserializeObject<A>(json, new KnownTypeConverter());
in the above case ret will be of type B.
JSON classes:
[KnownType(typeof(B))]
public class A
{
public string Name { get; set; }
}
public class B : A
{
public string LastName { get; set; }
}
Converter code:
/// <summary>
/// Use KnownType Attribute to match a divierd class based on the class given to the serilaizer
/// Selected class will be the first class to match all properties in the json object.
/// </summary>
public class KnownTypeConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return System.Attribute.GetCustomAttributes(objectType).Any(v => v is KnownTypeAttribute);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
// Load JObject from stream
JObject jObject = JObject.Load(reader);
// Create target object based on JObject
System.Attribute[] attrs = System.Attribute.GetCustomAttributes(objectType); // Reflection.
// Displaying output.
foreach (System.Attribute attr in attrs)
{
if (attr is KnownTypeAttribute)
{
KnownTypeAttribute k = (KnownTypeAttribute) attr;
var props = k.Type.GetProperties();
bool found = true;
foreach (var f in jObject)
{
if (!props.Any(z => z.Name == f.Key))
{
found = false;
break;
}
}
if (found)
{
var target = Activator.CreateInstance(k.Type);
serializer.Populate(jObject.CreateReader(),target);
return target;
}
}
}
throw new ObjectNotFoundException();
// Populate the object properties
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}