Point Serializer

The Point serializer stores geographic coordinates as GeoJSON Point objects, compatible with MongoDB’s geospatial queries.

Usage

using Cratis.Geospatial;

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

// Create a point
var point = new Point(longitude: -122.4194, latitude: 37.7749);

Storage Format

Points are serialized as GeoJSON Point documents:

{
  "_id": ObjectId("..."),
  "name": "Downtown Store",
  "location": {
    "type": "Point",
    "coordinates": [-122.4194, 37.7749]
  }
}

The coordinates array follows GeoJSON format: [longitude, latitude].

Querying

Finding Nearby Points

Use MongoDB’s $near operator with geospatial indexes:

// Create a geospatial index first
collection.Indexes.CreateOne(
    new CreateIndexModel<Store>(
        Builders<Store>.IndexKeys.Geo2DSphere(s => s.Location)
    )
);

// Query for stores near a point
var nearbyStores = await collection.Find(
    Builders<Store>.Filter.Near(
        s => s.Location,
        new Point(-122.4, 37.78),
        maxDistance: 5000 // 5km in meters
    )
).ToListAsync();

Checking if Point is Within Area

// Find points within a polygon boundary
var storesInArea = await collection.Find(
    Builders<Store>.Filter.GeoWithin(
        s => s.Location,
        polygon
    )
).ToListAsync();

Best Practices

Coordinate Order: Always use [longitude, latitude] (not latitude, longitude)
Create Indexes: Create 2dsphere indexes on Point properties for efficient spatial queries
Null Handling: Points can be nullable (Point?) for optional locations
Validation: Ensure longitude is between -180 and 180, latitude between -90 and 90

LineString — Routes and paths
Polygon — Geographic areas