When reading Geometry and Geography values from the database, we need to specify the SRID explicitly to retain it in the DbGeometry / DbGeography type. (#1038)

merging, thanks, and sorry for delay

Author: Nij4t2

Dapper.EntityFramework/DbGeographyHandler.cs

@@ -51,7 +51,7 @@ public override DbGeography Parse(object value)
             if (value == null || value is DBNull) return null;
             if (value is SqlGeography geo)
             {
-                return DbGeography.FromBinary(geo.STAsBinary().Value);
+                return DbGeography.FromBinary(geo.STAsBinary().Value, geo.STSrid.Value);
             }
             return DbGeography.FromText(value.ToString());
         }

Dapper.EntityFramework/DbGeometryHandler.cs

@@ -51,7 +51,7 @@ public override DbGeometry Parse(object value)
             if (value == null || value is DBNull) return null;
             if (value is SqlGeometry geo)
             {
-                return DbGeometry.FromBinary(geo.STAsBinary().Value);
+                return DbGeometry.FromBinary(geo.STAsBinary().Value, geo.STSrid.Value);
             }
             return DbGeometry.FromText(value.ToString());
         }

Dapper.Tests/Providers/EntityFrameworkTests.cs

@@ -1,5 +1,7 @@
 #if ENTITY_FRAMEWORK
+using System;
 using System.Data.Entity.Spatial;
+using System.Linq;
 using Xunit;
 
 namespace Dapper.Tests.Providers
@@ -16,7 +18,7 @@ public EntityFrameworkTests()
         public void Issue570_DbGeo_HasValues()
         {
             EntityFramework.Handlers.Register();
-            const string redmond = "POINT (122.1215 47.6740)";
+            const string redmond = "POINT (-122.1215 47.6740)";
             DbGeography point = DbGeography.PointFromText(redmond, DbGeography.DefaultCoordinateSystemId);
             DbGeography orig = point.Buffer(20);
 
@@ -34,6 +36,29 @@ public void Issue22_ExecuteScalar_EntityFramework()
             var geo2 = connection.ExecuteScalar<DbGeography>("select @geo", new { geo });
             Assert.NotNull(geo2);
         }
+
+        [Fact]
+        public void TestGeometryParsingRetainsSrid()
+        {
+            const int srid = 27700;
+            var s = $@"DECLARE @EdinburghPoint GEOMETRY = geometry::STPointFromText('POINT(258647 665289)', {srid});
+SELECT @EdinburghPoint";
+            var edinPoint = connection.Query<DbGeometry>(s).Single();
+            Assert.NotNull(edinPoint);
+            Assert.Equal(srid, edinPoint.CoordinateSystemId);
+        }
+
+        [Fact]
+        public void TestGeographyParsingRetainsSrid()
+        {
+            const int srid = 4324;
+            var s = $@"DECLARE @EdinburghPoint GEOGRAPHY = geography::STPointFromText('POINT(-3.19 55.95)', {srid});
+SELECT @EdinburghPoint";
+            var edinPoint = connection.Query<DbGeography>(s).Single();
+            Assert.NotNull(edinPoint);
+            Assert.Equal(srid, edinPoint.CoordinateSystemId);
+        }
+
     }
 }
 #endif