Point serializer

Arc stores Cratis.Geospatial.Point as GeoJSON. Complete MongoDB setup first; the snippets below are model declarations and query-method fragments, not a standalone host.

Usage

using Cratis.Geospatial;
using MongoDB.Bson;

public class Store
{
    public ObjectId Id { get; set; }
    public required string Name { get; set; }
    public required Point Location { get; set; }
}

Inside a method, construct a point with positional arguments or the correctly capitalized names:

var point = new Point(Longitude: -122.4194, Latitude: 37.7749);

Storage format

With camel-case naming, the location member is:

{"location":{"type":"Point","coordinates":[-122.4194,37.7749]}}

Coordinates are [longitude, latitude]. Validate ranges in your application; the record/serializer does not enforce geographic validity.

Point? expresses CLR optionality only. Arc’s current geometry BSON serializers neither serialize a null value nor read explicit BSON null. Design and test an omission policy or a null-aware member serializer before persisting optional geometry; a nullable annotation alone is insufficient. See serializer null handling.

Querying

The driver’s geometry arguments are GeoJsonPoint<GeoJson2DGeographicCoordinates>, not Cratis Point. The following fragment uses an IMongoCollection<Store> named collection:

using MongoDB.Driver;
using MongoDB.Driver.GeoJsonObjectModel;

await collection.Indexes.CreateOneAsync(new CreateIndexModel<Store>(
    Builders<Store>.IndexKeys.Geo2DSphere(store => store.Location)));

var origin = new GeoJsonPoint<GeoJson2DGeographicCoordinates>(
    new GeoJson2DGeographicCoordinates(-122.4, 37.78));
var nearbyStores = await collection.Find(Builders<Store>.Filter.Near(
    store => store.Location,
    origin,
    maxDistance: 5000)).ToListAsync();

This uses a 2dsphere index and a GeoJSON query point, so the distance bound is in meters. Index creation is normally deployment/setup work, not something to repeat on every query.

To find stored points within a region, use GeoWithin with a driver GeoJSON polygon. See polygon queries for construction and the distinction between containment and intersection. These examples establish API shape; test actual spatial results against your MongoDB deployment.

Continue with LineString for paths or Polygon for areas.