This is sample code to bind GeoRuby objects as SDO_GEOMETRY datatype. See: https://github.com/rsim/oracle-enhanced/pull/268

geometry-sample.rb

require 'oci8'
require 'geo_ruby'

module OCI8::Object::Mdsys
  class SdoGeometry < OCI8::Object::Base
    set_typename('MDSYS.SDO_GEOMETRY')
  end
end

class OCI8::BindType::GeoRuby < OCI8::BindType::Object
  def self.create(con, val, param, max_array_size)
    self.new(con, val, con.get_tdo_by_class(OCI8::Object::Mdsys::SdoGeometry), max_array_size)
  end

  def set(val)
    super(val && georuby_to_sdo_geometry(val))
  end

  def get()
    val = super()
    return nil if val.nil?
    elem_info = val.sdo_elem_info
    ordinates = val.sdo_ordinates
    sdo_geometry_to_georuby(val.sdo_gtype, val.sdo_srid, val.sdo_point, elem_info && elem_info.to_ary, ordinates && ordinates.to_ary)
  end

private
  def georuby_to_sdo_geometry(val)
    case val
    when GeoRuby::SimpleFeatures::Point
      # 2D or 3D Point-Only Geometry
      # http://docs.oracle.com/cd/E11882_01/appdev.112/e11830/sdo_objrelschema.htm#BGHIFACF
      # http://georuby.rubyforge.org/georuby-doc/classes/GeoRuby/SimpleFeatures/Point.html
      # I don't know how to handle the M coordinate.
      {
        :sdo_gtype => val.z ? 3001 : 2001,
        :sdo_srid => val.srid,
        :sdo_point => {
          :x => val.x,
          :y => val.y,
          :z => val.z
        },
        :sdo_elem_info => nil,
        :sdo_ordinates => nil
      }
    when GeoRuby::SimpleFeatures::LineString
      # as https://github.com/daqo/oracle-enhanced/blob/61385aafba140e4b72a0d8eeac1f58e9561a0cb3/lib/active_record/connection_adapters/oracle_enhanced_adapter.rb#L759 does.
      {
        :sdo_gtype => 2002,
        :sdo_srid => val.srid,
        :sdo_point => nil,
        :sdo_elem_info => [1, 2, 1],
        :sdo_ordinates => val.points.inject([]) do |ary, point|
          case point
          when GeoRuby::SimpleFeatures::Point
            ary << point.x
            ary << point.y
          when Array
            ary << point[0]
            ary << point[1]
          else
            raise "Unsupported type #{point.class}"
          end
          ary
        end
      }
    when GeoRuby::SimpleFeatures::Polygon
      # as https://github.com/daqo/oracle-enhanced/blob/61385aafba140e4b72a0d8eeac1f58e9561a0cb3/lib/active_record/connection_adapters/oracle_enhanced_adapter.rb#L782 does.
      {
        :sdo_gtype => 2003,
        :sdo_srid => val.srid,
        :sdo_point => nil,
        :sdo_elem_info => [1, 3, 1],
        :sdo_ordinates => val.rings.inject([]) do |ary, ring|
          ring.points.inject(ary) do |ary, point|
            case point
            when GeoRuby::SimpleFeatures::Point
              ary << point.x
              ary << point.y
            when Array
              ary << point[0]
              ary << point[1]
            else
              raise "Unsupported type #{point.class}"
            end
            ary
          end
          ary
        end
      }
    else
      raise "unsupported type #{val.class}"
    end
  end

  def sdo_geometry_to_georuby(gtype, srid, point, elem_info, ordinates)
    case gtype
    when 2001
      return GeoRuby::SimpleFeatures::Point.from_x_y(point.x, point.y, val.sdo_srid) if point
    when 3001
      return GeoRuby::SimpleFeatures::Point.from_x_y_z(point.x, point.y, point.z, val.sdo_srid) if point
    when 2002
      coordinates = []
      while not ordinates.empty?
        coordinates << [ordinates.shift, ordinates.shift]
      end
      return GeoRuby::SimpleFeatures::LineString.from_coordinates(coordinates, val.sdo_srid)
    end
    raise "Could not convert {:gtype => #{gtype}, :point => #{point}, :elem_info => #{elem_info}, :ordinates => #{ordinates}}, to GeoRuby"
  end
end

# for OCI8::Cursor#define
OCI8::BindType::Mapping[:geo_ruby] = OCI8::BindType::GeoRuby

# for OCI8::Cursor#bind_param
OCI8::BindType::Mapping[GeoRuby::SimpleFeatures::Point] = OCI8::BindType::GeoRuby
OCI8::BindType::Mapping[GeoRuby::SimpleFeatures::LineString] = OCI8::BindType::GeoRuby
OCI8::BindType::Mapping[GeoRuby::SimpleFeatures::Polygon] = OCI8::BindType::GeoRuby

if defined? ActiveRecord::ConnectionAdapters::SpatialOracleColumn
  OCI8::BindType::Mapping[ActiveRecord::ConnectionAdapters::SpatialOracleColumn] = OCI8::BindType::GeoRuby
end

if $0 == __FILE__
  #  -- You need to create test_sdo_geometry in advance.
  #  CREATE TABLE test_sdo_geometry (id varchar2(20), geo sdo_geometry)

  conn = OCI8.new('ruby/oci8@//localhost/XE')

  cursor = conn.parse('insert into test_sdo_geometry values(:1, :2)')

  point = GeoRuby::SimpleFeatures::Point.from_x_y(10,20,123)
  line = GeoRuby::SimpleFeatures::LineString.from_coordinates([[1.5,45.2],[-54.12312,-0.012]],256)

  cursor.bind_param(1, 'point')
  cursor.bind_param(2, point)
  cursor.exec

  cursor.bind_param(1, 'line')
  cursor.bind_param(2, line)
  cursor.exec

  cursor = conn.parse("select * from test_sdo_geometry where id in ('point', 'line')")
  
  # OCI8::Cursor#define(pos, :geo_ruby) is required to fetch a SDO_GEOMETRY column as a GeoRuby object for now.
  # Ruby-oci8 may be changed to work fine without this.
  cursor.define(2, :geo_ruby)
  
  cursor.exec do |row|
    case row[0]
    when 'point'
      raise "#{point} != #{row[1]}" if point != row[1]
    when 'line'
      raise "#{line} != #{row[1]}" if line != row[1]
    end
  end
end

I created an issue rsim/oracle-enhanced#310 on oracle-enhanced repo.

I am trying to hook this into my code, I need primarily to be able to set a MDSYS.SDO_GEOMETRY to NULL without errors. I have the impression it is not connected correctly. Where is the ActiveRecord::ConnectionAdapters::SpatialOracleColumn defined? It is imho not defined in oracle-enhanced.

This code is now in a initializer, but a MDSYS.SDO_GEOMETRY column is still not recognised when doing a bind_param.

ActiveRecord::ConnectionAdapters::SpatialOracleColumn is in https://github.com/ps2/spatial_adapter/blob/master/lib/spatial_adapter/oracle_enhanced.rb.

I had tested this code without rails. I posted a pull request to fix one issue with rails. But one issue remains. See rsim/oracle-enhanced#311.