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Cratis

Cratis Arc LineString storage and queries

Cratis Arc stores Cratis.Geospatial.LineString as a GeoJSON path so you can query for routes near a location or crossing a region. It preserves an ordered sequence of points; it does not compute distance traveled along a route.

Complete MongoDB setup to register the BSON serializers, which convert model values to MongoDB’s binary document format. The examples below add a route model and query fragments to that configured host.

Usage

Section titled “Usage”

Store the path on your route document:

using Cratis.Geospatial;
using MongoDB.Bson;


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

Inside a method, construct the path in travel order. Each point takes longitude first, then latitude:

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

Storage format

Section titled “Storage format”

With camel-case naming configured, Arc writes the path member as:

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

Each coordinate pair is [longitude, latitude]. Provide at least two points in their intended order and validate geographic ranges before storage. Neither the Cratis record nor the serializer checks the point count or ranges. MongoDB may reject invalid geometry when indexing or querying it.

Querying

Section titled “Querying”

To find routes near a location, query the path against a driver GeoJSON point. This method fragment uses an IMongoCollection<DeliveryRoute> named collection. Create the spatial index during setup, then use the filter when querying:

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 stored path is a Cratis LineString, while the query origin is a driver GeoJsonPoint<GeoJson2DGeographicCoordinates>. For this GeoJSON query, maxDistance: 1000 sets a 1,000-meter proximity bound. It does not measure distance traveled along the line. Keep index creation out of the per-query path.

For routes crossing a region, use GeoIntersects with a driver GeoJSON polygon. Use GeoWithin when the stored geometry must be contained within the query area. Polygon construction and queries shows the polygon argument; using it in a filter does not require reading stored Cratis polygons.

Limits

Section titled “Limits”

LineStringSerializer supplies the GeoJSON representation. Your application still owns geometry validation and routing logic, and arbitrary geometry methods are not guaranteed to translate into MongoDB queries. Check boundary cases and spatial results against your target MongoDB version.

If a path is optional, LineString? only makes the .NET property nullable. Arc’s current geometry BSON serializers neither write a null value nor read explicit BSON null. Choose and test an omission policy or a null-aware member serializer before persisting optional paths. Serializer null handling explains the difference between an absent field and an explicit null.

Use Point storage and queries when each document needs one location. For service areas and other boundaries, read the Polygon guide, including its typed-read limitation.

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