Deserializing polymorphic json classes without type information using json.net

Question

This Imgur api call returns a list containing both Gallery Image and Gallery Album classes represented in JSON.

I can\'t see how to

Answer 1

I'm only posting this to clear up some of the confusion. If you are working with a predefined format and need to deserialize it, this is what I found worked best and demonstrates the mechanics so that others can tweak it as needed.

public class BaseClassConverter : JsonConverter
    {
        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            var j = JObject.Load(reader);
            var retval = BaseClass.From(j, serializer);
            return retval;
        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            serializer.Serialize(writer, value);
        }

        public override bool CanConvert(Type objectType)
        {
            // important - do not cause subclasses to go through this converter
            return objectType == typeof(BaseClass);
        }
    }

    // important to not use attribute otherwise you'll infinite loop
    public abstract class BaseClass
    {
        internal static Type[] Types = new Type[] {
            typeof(Subclass1),
            typeof(Subclass2),
            typeof(Subclass3)
        };

        internal static Dictionary TypesByName = Types.ToDictionary(t => t.Name.Split('.').Last());

        // type property based off of class name
        [JsonProperty(PropertyName = "type", Required = Required.Always)]
        public string JsonObjectType { get { return this.GetType().Name.Split('.').Last(); } set { } }

        // convenience method to deserialize a JObject
        public static new BaseClass From(JObject obj, JsonSerializer serializer)
        {
            // this is our object type property
            var str = (string)obj["type"];

            // we map using a dictionary, but you can do whatever you want
            var type = TypesByName[str];

            // important to pass serializer (and its settings) along
            return obj.ToObject(type, serializer) as BaseClass;
        }


        // convenience method for deserialization
        public static BaseClass Deserialize(JsonReader reader)
        {
            JsonSerializer ser = new JsonSerializer();
            // important to add converter here
            ser.Converters.Add(new BaseClassConverter());

            return ser.Deserialize(reader);
        }
    }