How to add custom field type in ServiceStack.OrmLite which uses db function?

Question

How custom field types can be used which calls db extension functions? In this case PostGIS .

From PostGIS install page slightly altered:

CREATE TABLE 
  mytable ( 
    id SERIAL PRIMARY KEY,
    geom GEOMETRY(POINT, 26910)
  )
; 

INSERT INTO 
  mytable (geom) 
VALUES 
  (ST_GeomFromText('POINT(0 0)', 26910))
;

SELECT 
  id
FROM 
  mytable
WHERE 
  ST_DWithin(geom, ST_GeomFromText('POINT(0 0)', 26910), 1000)
;

How this table is generated in code? And how it is queried?

class mytable
{
  [AutoIncrement]
  [PrimaryKey]
  public int id;

  [???]
  public ??? geom;
}

Related SO question: How to define 'geography' type using Npgsql and OrmLite (using postgresql, postgis, c#)

Answer 1

Rather an old question but it came up for me when I was looking at this so I thought I would add this in case it helps others. Note that there may well be a better way to do this in ServiceStack now as it has massively increased functionality since the original question

I haven't yet been able to get this working using ServiceStack (the geometry fields return as null) but I have using Npgsql as follows.

SELECT - use ::Text as follows -

       var conn = new NpgsqlConnection(connectionString);
        conn.Open();

        var cmd = new NpgsqlCommand(
            "select  id, geom :: TEXT from mytable", conn);

INSERT - use a standard insert as follows -

         var conn = new NpgsqlConnection(connectionString);
        conn.Open();

        using (var cmd = new NpgsqlCommand(
            "INSERT INTO mytable( geom) VALUES ( st_geomfromtext ( 'POINT(0,0)':: TEXT, 1000))",
            conn)){cmd.ExecuteNonQuery()}