.NET Standard 2.0 library with OGC extensions methods on geometry (NpgsqlTypes.PostgisGeometry
or NetTopologySuite.Geometries.Geometry
) instances, providing strongly typed access to PostGIS functions on server side while using linq2db LINQ to database provider.
NpgsqlTypes.PostgisGeometry
or NetTopologySuite.Geometries.Geometry
gets additional methods, similar to Microsoft.SqlServer.Types.SqlGeometry
OGC Methods on Geometry Instances or
NetTopologySuite plugin for Entity Framework Core for PostgreSQL.
These methods will be translated into PostGIS SQL operations, so evaluation will happen on the server side. Calling these methods on client side results in throwing InvalidOperationException
.
Naming convention follows OGC methods names, starting with ST*
prefix.
Using extensions methods inside LINQ expression (Npgsql 4):
using LinqToDBPostGisNetTopologySuite
using (var db = new PostGisTestDataConnection())
{
NetTopologySuite.Geometries.Point point = new Point(new Coordinate(1492853, 6895498)) { SRID = 3857 };
var dms = db.Select(() => GeometryOutput.STAsLatLonText(point));
var nearestCity = db.Cities
.OrderBy(c => c.Geometry.STDistance(point))
.FirstOrDefault();
var selected = db.Polygons
.Where(p => p.Geometry.STArea() > 150.0)
.OrderBy(p => p.Geometry.STDistance(point))
.ToList();
var stats = db.Polygons
.Select(c => new
{
Id = c.Id,
Name = c.Name,
Area = c.Geometry.STArea(),
Distance = c.Geometry.STDistance(point),
NumPoints = c.Geometry.STNPoints(),
Srid = c.Geometry.STSrId(),
Wkt = c.Geometry.STAsText(),
})
.ToList();
}
[Table("test_geometry", Schema = "public")]
public class PolygonEntity
{
[Column("geom")]
public NetTopologySuite.Geometries.Geometry Geometry { get; set; }
}
[Table("owm_cities", Schema = "public")]
public class CityEntity
{
[Column("geom")]
public NetTopologySuite.Geometries.Geometry Geometry { get; set; }
}
class PostGisTestDataConnection : LinqToDB.Data.DataConnection
{
public ITable<PolygonEntity> Polygons { get { return GetTable<PolygonEntity>(); } }
public ITable<CityEntity> Cities { get { return GetTable<CityEntity>(); } }
}
Developed using MS Visual Studio 2019. Tested on PostgreSQL version 9.6/11, PostGIS version 2.5/3.0/3.1/3.2. Depends on linq2db, Npgsql.
SELECT PostGIS_Full_Version()
query to check PostGIS version.Sql\create_tables.sql
in this database.LinqToDBPostGis.sln
in Visual Studio.App.config
of all projects.geography
data type.