LineString serializer

Arc’s LineStringSerializer stores a Cratis line as GeoJSON. Use it for paths, not for computed distance along a route. Complete MongoDB setup before these model/query fragments.

Usage

using Cratis.Geospatial;
using MongoDB.Bson;

public class DeliveryRoute
{
    public ObjectId Id { get; set; }
    public required LineString Path { get; set; }
}

Construction fragment inside a method:

var route = new LineString([
    new Point(-122.4194, 37.7749),
    new Point(-122.4185, 37.7750),
    new Point(-122.4170, 37.7755)
]);

Storage format

With camel-case naming, the path member is:

{"path":{"type":"LineString","coordinates":[[-122.4194,37.7749],[-122.4185,37.775],[-122.417,37.7755]]}}

Provide at least two points in their intended order. The Cratis record/serializer does not validate that count or geographic ranges. MongoDB may reject invalid geometry when indexing or querying it.

Querying

For an IMongoCollection<DeliveryRoute> named collection, this method fragment finds nearby routes:

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

await collection.Indexes.CreateOneAsync(new CreateIndexModel<DeliveryRoute>(
    Builders<DeliveryRoute>.IndexKeys.Geo2DSphere(route => route.Path)));
var origin = new GeoJsonPoint<GeoJson2DGeographicCoordinates>(
    new GeoJson2DGeographicCoordinates(-122.418, 37.775));
var nearby = await collection.Find(Builders<DeliveryRoute>.Filter.Near(
    route => route.Path, origin, maxDistance: 1000)).ToListAsync();

The filter argument is a driver GeoJSON point, not a Cratis point. Perform index creation during setup. The radius is in meters for this GeoJSON query; it is not distance traveled along the line.

To find routes crossing a region, use GeoIntersects with a driver GeoJSON polygon. GeoWithin instead asks whether the stored geometry is contained within the query area. See polygon construction and queries.

Limits

Serialization supplies a GeoJSON shape, not validation, a routing engine, or guaranteed query translation from arbitrary geometry methods. Test boundary cases and spatial query results in your target MongoDB version.

LineString? 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.

See Point and Polygon for the other supported geometry types.