Convert between SqlGeometry and DbGeometry

Question

Is there a simple way to convert between SqlGeometry and DbGeometry? I'm using a popular sql spatial helper library and all of the functions in there expect SqlGeometry. But when i use Entity Framework against an ESRI ArcSDE feature class the Shape field is returned as a DbGeometry. I can't call any of the methods I would like to (such as LocateAlongGeom) with that DbGeometry type. Maybe there is a way to serialize it as binary or text then read it back in as a SqlGeometry?

Geniegenii

Answer 1

//Convert from SqlGeometry to DbGeometry 
SqlGeometry sqlGeo = ...
DbGeometry dbGeo = DbGeometry.FromBinary(sqlGeo.STAsBinary().Buffer);

//Convert from DBGeometry to SqlGeometry
 SqlGeometry sqlGeo2 = SqlGeometry.STGeomFromWKB(new SqlBytes(dbGeo.AsBinary()), 0);

Symphysis

Shouldn't the DbGeometry to SqlGeometry conversion be... SqlGeometry sqlGeo2 = SqlGeometry.STGeomFromWKB(new SqlBytes(dbGeo.AsBinary()), dbGeo.CoordinateSystemId); To account for geometries that aren't in SRID-0? – Scintillate

Yes, I would assume you'd want to pass in the SRID in most cases. For most GPS coordinates you'd use 4326 for WGS84. spatialreference.org/ref/epsg/4326 – Unbidden

I believe you can also detect it dynamically using dbGeo.CoordinateSystemId in place of the zero above. – Unbidden

Answer 2

An easy way to manage multiple spatial types is via extension methods, like so: (using slightly modified versions of the code samples from @BizarroDavid)

public static class GeometryExtensions
{
    public static DbGeometry ToDbGeometry(this SqlGeometry sqlGeometry)
    {
        return DbGeometry.FromBinary(sqlGeometry.STAsBinary().Buffer);
    }

    public static SqlGeometry ToSqlGeometry(this DbGeometry dbGeometry)
    {
        return SqlGeometry.STGeomFromWKB(new SqlBytes(dbGeometry.AsBinary()), dbGeometry.CoordinateSystemId);
    }
}

Once you have them implemented, you can use them like so...

DbGeometry anyDbGeometry;
SqlGeometry anySqlGeometry;

//Convert to DbGeometry
anyDbGeometry = anySqlGeometry.ToDbGeometry();

//Convert to SqlGeometry
anySqlGeometry = anyDbGeometry.ToSqlGeometry();

Unbidden

Answer 3

Entity Framework doesn't support CURVES (CIRCLE) -> change to lines:

return DbGeometry.FromBinary(sqlGeometry.**STCurveToLine()**.STAsBinary().Buffer);

Kendricks