Serialize data from PostGIS to JSON - serialization

Question

I'm working on a .NET Core REST service which will have a controller that will send geometry data back a GeoJson so I can show it on my Leaflet map.
I'm having trouble converting my class to JSON.
I've tried this:
StringBuilder sb = new StringBuilder();
JsonTextWriter writer = new JsonTextWriter(new StringWriter(sb));
var jsonSerializer = GeoJsonSerializer.Create(new JsonSerializerSettings()
{NullValueHandling = NullValueHandling.Ignore});
jsonSerializer.Serialize(writer, _context.Locations);
writer.Flush();
return Ok(sb.ToString());
But then I get this error
Self referencing loop detected for property 'CoordinateValue' with type 'GeoAPI.Geometries.Coordinate'
I've been looking for examples and reading docs all day but can't get it to work.
The class I need to serialize:
public class SobekLocation
{
public int Id { get; set; }
public string LocationId { get; set; }
public bool Use { get; set; }
public Point Location { get; set; }
}
Any suggestions are much appreciated.
Edit:
I'm making my own featurecollection and am trying to serialize that. It is doing something but it is not valid GeoJSON.
public FeatureCollection GetLocationsAsFeatureCollection()
{
var featureCollection = new FeatureCollection();
foreach (var location in GetLocations().Take(5))
{
var attr = new AttributesTable
{
{"Id", location.Id},
{"Use", location.Use},
{"LocationId", location.LocationId}
};
var feature = new Feature(location.Location, attr);
featureCollection.Add(feature);
}
return featureCollection;
}
And de serialization part:
var fc = _service.GetLocationsAsFeatureCollection();
var sb = new StringBuilder();
var jsonSerializer = JsonSerializer.Create(new JsonSerializerSettings
{
// To prevent the Self referencing loop error:
ReferenceLoopHandling = ReferenceLoopHandling.Ignore
});
using (var sw = new StringWriter(sb))
{
jsonSerializer.Serialize(sw, fc);
}
return Ok(sb.ToString());
The serialized data:
{
"Features":[
{
"Geometry":{
"CoordinateSequence":{
"Dimension":3,
"Ordinates":7,
"Count":1
},
"Coordinates":[
{
"X":191390.015,
"Y":523064.716597462,
"Z":"NaN"
}
],
"NumPoints":1,
"IsEmpty":false,
"Dimension":0,
"BoundaryDimension":-1,
"X":191390.015,
"Y":523064.716597462,
"Coordinate":{
"X":191390.015,
"Y":523064.716597462,
"Z":"NaN"
},
"GeometryType":"Point",
"OgcGeometryType":1,
"Boundary":[
],
"Z":"NaN",
"M":"NaN",
"Factory":{
"PrecisionModel":{
"IsFloating":true,
"MaximumSignificantDigits":16,
"Scale":0,
"PrecisionModelType":0,
"OffsetX":0,
"OffsetY":0
},
"CoordinateSequenceFactory":{
"Ordinates":7
},
"SRID":28992
},
"UserData":null,
"SRID":28992,
"PrecisionModel":{
"IsFloating":true,
"MaximumSignificantDigits":16,
"Scale":0,
"PrecisionModelType":0,
"OffsetX":0,
"OffsetY":0
},
"NumGeometries":1,
"IsSimple":true,
"IsValid":true,
"Area":0,
"Length":0,
"EnvelopeInternal":{
"IsNull":false,
"Width":0,
"Height":0,
"MinX":191390.015,
"MaxX":191390.015,
"MinY":523064.716597462,
"MaxY":523064.716597462,
"Area":0,
"MinExtent":0,
"MaxExtent":0,
"Centre":{
"X":191390.015,
"Y":523064.716597462,
"Z":"NaN"
}
},
"IsRectangle":false
},
"Attributes":[
{
"Key":"Id",
"Value":1
},
{
"Key":"Use",
"Value":false
},
{
"Key":"LocationId",
"Value":"KNP_1"
}
],
"BoundingBox":null
}
],
"Type":"FeatureCollection",
"CRS":null,
"Count":5,
"BoundingBox":null
}
As you can see all properties start with an uppercase but they should be in lowercase. And after changing the properties manually geojsonlint.com reports: GeoJSON features must have a type=feature member
Edit2:
I've made some progress. I'm using the GeoJSON.Net package now and I can now create valid GeoJSON accordin to http://geojsonlint.com/. But still my Leaflet map is complaining about invalid GeoJSON so the map is still not showing anything ;)
Here's my new converter:
public GeoJSON.Net.Feature.FeatureCollection GetLocationsAsGeoJsonFeatureCollection()
{
var featureCollection = new GeoJSON.Net.Feature.FeatureCollection();
foreach (var location in GetLocations())
{
var attr = new Dictionary<string, object>()
{
{"Id", location.Id},
{"Use", location.Use},
{"LocationId", location.LocationId}
};
var position = new Position(location.Location.Coordinate.X, location.Location.Coordinate.Y);
var geom = new GeoJSON.Net.Geometry.Point(position);
var feature = new GeoJSON.Net.Feature.Feature(geom, attr, location.Id.ToString());
featureCollection.Features.Add(feature);
}
return featureCollection;
}
And the GeoJSON it produces:
{
"type":"FeatureCollection",
"features":[
{
"type":"Feature",
"id":"1",
"geometry":{
"type":"Point",
"coordinates":[
523064.716597462,
191390.015
]
},
"properties":{
"id":1,
"use":false,
"locationId":"KNP_1"
}
},
{
"type":"Feature",
"id":"2",
"geometry":{
"type":"Point",
"coordinates":[
519349.860113963,
170162.249352578
]
},
"properties":{
"id":2,
"use":false,
"locationId":"CP_6"
}
},
{
"type":"Feature",
"id":"3",
"geometry":{
"type":"Point",
"coordinates":[
519952.507022603,
170402.383673312
]
},
"properties":{
"id":3,
"use":false,
"locationId":"CP_UR_5_1"
}
},
{
"type":"Feature",
"id":"4",
"geometry":{
"type":"Point",
"coordinates":[
519948.062527202,
170582.612655391
]
},
"properties":{
"id":4,
"use":false,
"locationId":"CP_UR_6_1"
}
},
{
"type":"Feature",
"id":"5",
"geometry":{
"type":"Point",
"coordinates":[
519902.432252114,
170602.894875503
]
},
"properties":{
"id":5,
"use":false,
"locationId":"CP_UR_6_2"
}
}
]
}
This is my code for Leaflet:
L.geoJson('http://localhost:5000/api/data/',
{
attribution: 'Mine'
}
).addTo(map);
I'm still looking for advice how to easily plot my PostGIS data on a Leaflet map.