WebApi GeoJson error serializing data

Question

I have a web service trying to return GeoJson data, I keep getting this error

{"Message":"An error has occurred.","ExceptionMessage":"The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'.","ExceptionType":"System.InvalidOperationException","StackTrace":null,"InnerException":{"Message":"An error has occurred.","ExceptionMessage":"The method or operation is not implemented.","ExceptionType":"System.NotImplementedException","StackTrace":" at GeoJSON.Net.Converters.GeometryConverter.WriteJson(JsonWriter writer, Object value, JsonSerializer serializer)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeConvertable(JsonWriter writer, JsonConverter converter, Object value, JsonContract contract, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IEnumerable values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value, Type objectType)\r\n at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value, Type objectType)\r\n at Newtonsoft.Json.JsonSerializer.Serialize(JsonWriter jsonWriter, Object value)\r\n at System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, Encoding effectiveEncoding)\r\n at System.Net.Http.Formatting.JsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, Encoding effectiveEncoding)\r\n at System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, HttpContent content)\r\n at System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext, CancellationToken cancellationToken)\r\n--- End of stack trace from previous location where exception was thrown ---\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.GetResult()\r\n at System.Web.Http.WebHost.HttpControllerHandler.d__14.MoveNext()"}}

This is my controller

 // POST api/geo
    public List<GeoJSON.Net.Feature.Feature> Post([FromBody] locationsClass loc)
    {

        var lat = loc.lat;
        var lon = loc.lon;
        Geo Geo = new Geo();
        return Geo.GetRndNearybyLocationList(lat, lon, 400); 
    }

This is the method GetRndNearybyLocationList

        public List<GeoJSON.Net.Feature.Feature> GetRndNearybyLocationList(double lat, double lon, int meters)
    {
        LocationObject thisRndLocation = new LocationObject();
        List<LocationObject> locationsList = new List<LocationObject>();

        //List<GeoJSON.Net.Geometry.GeographicPosition> Positions = new List<GeoJSON.Net.Geometry.GeographicPosition>();

        Random rnd = new Random();
        int dice = rnd.Next(1, 7);
        List<GeoJSON.Net.Feature.Feature> featureList = new List<GeoJSON.Net.Feature.Feature>();
        for (int i = 1; i <= dice; i++)
        {
            thisRndLocation = getLocation(lat, lon, meters);

            GeoJSON.Net.Geometry.GeographicPosition latlon = new GeoJSON.Net.Geometry.GeographicPosition(thisRndLocation.lat, thisRndLocation.lon, 0);
            GeoJSON.Net.Geometry.Point point = new GeoJSON.Net.Geometry.Point(latlon);
            Dictionary<string, object> properties = new Dictionary<string, object>();
            properties.Add("Color", "Blue");
            GeoJSON.Net.Feature.Feature feature = new GeoJSON.Net.Feature.Feature(point, properties);
            feature.Id = "FeatureId: " + i;
            featureList.Add(feature);

            //var coOrdinates = new GeoJSON.Net.Geometry.GeographicPosition(thisRndLocation.lat, thisRndLocation.lon);
            //Positions.Add(coOrdinates);
            //locationsList.Add(thisRndLocation);
            //var x = locationsList;

        }
        return featureList;
    }

In fiddler I get the error , this is my Ajax

   $.ajax({
            type: 'Post',
            contentType: "application/json; charset=utf-8",
            url: 'http://localhost:8506/api/' + 'Geo' + '/?alloworigin=true',
            data: JSON.stringify({ lat: lat, lon: lon }),
            dataType: 'json',
            success: function (data) {
                for (var i = 0; i < data.length; i++) {
                    var obj = data[i];
                    console.log(obj.id);
                }
            },
            error: function (msg) {
                alert(msg.responsetext);
            }
        });

Things I have tried Updgraded newtonsoft to version 6

adding this line to application_start

GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;

override in the Register method of the WebApi Config:

 var json = config.Formatters.JsonFormatter;
    json.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects;
    config.Formatters.Remove(config.Formatters.XmlFormatter);

So far no good, any ideas anyone ? , thx

here's the fixed class, ensure you use the correct base GeoJSon

namespace GeoJSON.Net.Geometry
{
using System;
using System.Collections.Generic;
using Newtonsoft.Json;



/// <summary>
/// In geography, a point refers to a Position on a map, expressed in latitude and longitude.
/// </summary>
/// <seealso cref="http://geojson.org/geojson-spec.html#point"/>
public class Point : GeoJSONObject, IGeometryObject
{

    /// <summary>
    /// Initializes a new instance of the <see cref="Point"/> class.
    /// </summary>
    /// <param name="coordinates">The Position.</param>
    public Point(GeoJSON.Net.Geometry.GeographicPosition coordinates)
    {
        if (coordinates == null)
        {
            throw new ArgumentNullException("coordinates");
        }

        this.Coordinates = new List<GeoJSON.Net.Geometry.GeographicPosition> { coordinates };
        this.Type = GeoJSONObjectType.Point;
    }


    /// <summary>
    /// Initializes a new instance of the <see cref="Point"/> class.
    /// </summary>
    /// <param name="coordinates">The Position.</param>
    public Point(List<GeoJSON.Net.Geometry.GeographicPosition> coordinates)
    {
        if (coordinates == null)
        {
            throw new ArgumentNullException("coordinates");
        }

        this.Coordinates = coordinates;
        this.Type = GeoJSONObjectType.Point;
    }

    /// <summary>
    /// Gets the Coordinate(s).
    /// </summary>
    /// <value>The Coordinates.</value>
    [JsonProperty(PropertyName = "coordinates", Required = Required.Always)]
    //[JsonConverter(typeof(PositionConverter))]
    public List<GeoJSON.Net.Geometry.GeographicPosition> Coordinates { get; private set; }
}

}

Answer 1

It looks to me that the library for GeoJSON has not yet implemented the write method. If we pop over to the source for that file at github then we can see that it is, in fact, not implemented yet. However there are some forks of the project which do seem to have implementations in place. You might try downloading the code for mapbutcher's fork and building it.