Entity Framework Core LineString conversion

Use AsLineString() to store a route’s ordered points as a plain JSON string in Entity Framework Core. Configure the property explicitly: BaseDbContext does not apply this converter automatically, and it does not provide native spatial mapping.

Define and configure a route

Define a route with a Cratis.Geospatial.LineString property:

using Cratis.Geospatial;

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

In your context’s OnModelCreating, with Cratis.Arc.EntityFrameworkCore and Microsoft.EntityFrameworkCore imported:

modelBuilder.Entity<DeliveryRoute>().Property(route => route.Path).AsLineString();

Inside a method, construct the route from points in longitude, latitude order:

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

The converter’s plain System.Text.Json output is:

{"Coordinates":[{"Longitude":-122.4194,"Latitude":37.7749},{"Longitude":-122.4185,"Latitude":37.775}]}

This is not GeoJSON, the geographic JSON format that uses a geometry type and numeric coordinate arrays. Neither the LineString record nor its string converter enforces a minimum of two points. Validate the sequence before persisting it.

Storage and queries

AsLineString() sets a value converter; it does not select a SQL column type or create a spatial index. It also does not add a structural value comparer to compare coordinate-array contents. Test the equality and change-tracking behavior your application depends on, especially when modifying an array in place. String conversion alone does not translate nested-coordinate LINQ expressions into SQL.

There is no LineStringColumn() helper for CreateTable. The separate AddLineStringColumn() migration helper declares geometry(LineString, 4326) on PostgreSQL, geography on SQL Server, and TEXT on SQLite. It does not make the string converter compatible with native spatial columns.

Use the storage-path matrix to choose between explicit string conversion, [Json], and application-configured native spatial mapping. Continue with Polygon conversion for areas.