Deserializing DbGeometry with Newtonsoft.Json

Question

I\'m building a SPA using Angular,Breeze and Web API 2 following the approach as outlined by John Papa in his latest PluralSight course.

Everything works well and I can

Answer 1

System.Data.Spatial.DbGeometry does not play nicely with Newtonsoft.Json

You need to create a JsonConverter to convert the DbGeometry

public class DbGeometryConverter : JsonConverter
    {
        public override bool CanConvert(Type objectType)
        {
            return objectType.IsAssignableFrom(typeof(string));
        }

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            JObject location = JObject.Load(reader);
            JToken token = location["Geometry"]["WellKnownText"];
            string value = token.ToString();

            DbGeometry converted = DbGeometry.PolygonFromText(value, 2193);
            return converted;
        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            // Base serialization is fine
            serializer.Serialize(writer, value);
        }
    }

Then on your property in your model add the attribute

[JsonConverter(typeof(DbGeometryConverter))]
public DbGeometry Shape { get; set; }

Now when you hit your BreezeController the deserialization will be handled by our new DbGeometryConverter.

Hope it helps.