import cx_Oracle

from django.db.backends.oracle.introspection import DatabaseIntrospection

class OracleIntrospection(DatabaseIntrospection):

    # Associating any OBJECTVAR instances with GeometryField.  Of course,

    # this won't work right on Oracle objects that aren't MDSYS.SDO_GEOMETRY,

    # but it is the only object type supported within Django anyways.

    data_types_reverse = DatabaseIntrospection.data_types_reverse.copy()

    data_types_reverse[cx_Oracle.OBJECT] = 'GeometryField'

    def get_geometry_type(self, table_name, geo_col):

        cursor = self.connection.cursor()

        try:

            # Querying USER_SDO_GEOM_METADATA to get the SRID and dimension information.

            try:

                cursor.execute('SELECT "DIMINFO", "SRID" FROM "USER_SDO_GEOM_METADATA" WHERE "TABLE_NAME"=%s AND "COLUMN_NAME"=%s',

                               (table_name.upper(), geo_col.upper()))

                row = cursor.fetchone()

            except Exception, msg:

                raise Exception('Could not find entry in USER_SDO_GEOM_METADATA corresponding to "%s"."%s"\n'

                                'Error message: %s.' % (table_name, geo_col, msg))

            # TODO: Research way to find a more specific geometry field type for

            # the column's contents.

            field_type = 'GeometryField'

            # Getting the field parameters.

            field_params = {}

            dim, srid = row

            if srid != 4326:

                field_params['srid'] = srid

            # Length of object array ( SDO_DIM_ARRAY ) is number of dimensions.

            dim = len(dim)

            if dim != 2:

                field_params['dim'] = dim

        finally:

            cursor.close()

        return field_type, field_params