https://github.com/apdevelop/linq2db-postgis-extensions
.NET Standard 2.0 library with extensions methods for PostGIS geometries methods access with linq2db
https://github.com/apdevelop/linq2db-postgis-extensions
csharp dotnet geometry linq2db netstandard20 nettopologysuite npgsql ogc postgis postgresql spatial
Last synced: 15 days ago
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.NET Standard 2.0 library with extensions methods for PostGIS geometries methods access with linq2db
- Host: GitHub
- URL: https://github.com/apdevelop/linq2db-postgis-extensions
- Owner: apdevelop
- License: mit
- Created: 2017-02-26T12:09:04.000Z (almost 9 years ago)
- Default Branch: master
- Last Pushed: 2024-05-09T15:27:50.000Z (over 1 year ago)
- Last Synced: 2025-10-24T06:27:37.178Z (3 months ago)
- Topics: csharp, dotnet, geometry, linq2db, netstandard20, nettopologysuite, npgsql, ogc, postgis, postgresql, spatial
- Language: C#
- Homepage:
- Size: 394 KB
- Stars: 24
- Watchers: 4
- Forks: 5
- Open Issues: 7
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-gis - Linq2db-Postgis-Extensions - .NET Standard 2.0 library with OGC extensions methods on geometry (`NpgsqlTypes.PostgisGeometry` or `NetTopologySuite.Geometries.Geometry`) instances, providing strongly typed access to [PostGIS](http://postgis.net/) functions on server side while using [linq2db](https://github.com/linq2db/linq2db) LINQ to database provider. (Geospatial Library / C Sharp)
README
# Linq2db PostGIS Extensions
.NET Standard 2.0 library with OGC extensions methods on geometry (`NpgsqlTypes.PostgisGeometry` or `NetTopologySuite.Geometries.Geometry`) instances, providing strongly typed access to [PostGIS](http://postgis.net/) functions on server side while using [linq2db](https://github.com/linq2db/linq2db) LINQ to database provider.
### Two implementations
| Property | LinqToDBPostGisNpgsqlTypes | LinqToDBPostGisNetTopologySuite |
| -------------- |:---------------------------:|:------------------------------------:|
| Extending type | `NpgsqlTypes.PostgisGeometry` | `NetTopologySuite.Geometries.Geometry` |
| Npgsql version | 3.x | 4.x |
| PostGIS reference version | 1.5 | 3.0/3.1/3.2/3.3 |
| Status | Legacy | Active |
| NuGet | — | [](https://www.nuget.org/packages/LinqToDBPostGisNTS/) |
| Dependencies | linq2db, Npgsql | linq2db (>= 3.0.0),
NetTopologySuite (>= 2.0.0),
NetTopologySuite.IO.PostGis (>= 2.0.0),
Npgsql (>= 4.1.0),
Npgsql.NetTopologySuite (>= 4.1.0) |
### Usage
`NpgsqlTypes.PostgisGeometry` or `NetTopologySuite.Geometries.Geometry` gets additional methods, similar to `Microsoft.SqlServer.Types.SqlGeometry`
[OGC Methods on Geometry Instances](https://docs.microsoft.com/sql/t-sql/spatial-geometry/ogc-methods-on-geometry-instances?view=sql-server-2016) or
[NetTopologySuite plugin for Entity Framework Core for PostgreSQL](https://www.npgsql.org/efcore/mapping/nts.html).
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):
```c#
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();
}
```
```c#
[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 Polygons { get { return GetTable(); } }
public ITable Cities { get { return GetTable(); } }
}
```
### Technologies
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](https://github.com/linq2db/linq2db), [Npgsql](https://github.com/npgsql/npgsql).
### Getting started with demo application
* Make sure you have PostgreSQL DBMS with PostGIS extension installed. Execute `SELECT PostGIS_Full_Version()` query to check PostGIS version.
* Create new database named "postgistest" (or any other name), add support of spatial features for this database.
* Execute SQL script `Sql\create_tables.sql` in this database.
* Open solution `LinqToDBPostGis.sln` in Visual Studio.
* Check database connection string in `App.config` of all projects.
* Run application, view table data along with PostGIS functions results in console output.
### TODOs
* Implement full set of PostGIS methods.
* Add support for PostGIS `geography` data type.
* Test on various versions of PostgreSQL/PostGIS and platforms (including .NET 5 and later).
* More tests for corner cases.
### References
* [PostGIS Reference](https://postgis.net/docs/reference.html)
* [PostGIS/NetTopologySuite Type Plugin](https://www.npgsql.org/doc/types/nts.html)
* [Spatial Mapping with NetTopologySuite in Entity Framework Core](https://www.npgsql.org/efcore/mapping/nts.html)
* [How to teach LINQ to DB convert custom .NET methods and objects to SQL - Sql.Function attribute](http://blog.linq2db.com/2016/06/how-to-teach-linq-to-db-convert-custom.html)