How to cast JObject in JSON.Net to T

Question

I know that I can use JsonConvert.DeserializeObject<T>(string), however, I need to peek into the object's _type (which may not be the first parameter) in order to determine the specific class to cast to. Essentially, what I am wanting to do is something like:

//Generic JSON processor for an API Client. function MyBaseType ProcessJson(string jsonText) {   var obj = JObject.Parse(jsonText);   switch (obj.Property("_type").Value.ToString()) {     case "sometype":       return obj.RootValue<MyConcreteType>();       //NOTE: this doesn't work...        // return obj.Root.Value<MyConcreteType>();     ...   } } ...  // my usage... var obj = ProcessJson(jsonText); var instance = obj as MyConcreteType; if (instance == null) throw new MyBaseError(obj); 

Answer 1

First parse the JSON into a JObject. Then lookup the _type attribute using LINQ to JSON. Then switch depending on the value and cast using ToObject<T>:

var o = JObject.Parse(text); var jsonType = (String)o["_type"];  switch(jsonType) {     case "something": return o.ToObject<Type>();     ... }