from MySQLdb.constants import FIELD_TYPE

from django.contrib.gis.gdal import OGRGeomType

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

class MySQLIntrospection(DatabaseIntrospection):

    # Updating the data_types_reverse dictionary with the appropriate

    # type for Geometry fields.

    data_types_reverse = DatabaseIntrospection.data_types_reverse.copy()

    data_types_reverse[FIELD_TYPE.GEOMETRY] = 'GeometryField'

    def get_geometry_type(self, table_name, geo_col):

        cursor = self.connection.cursor()

        try:

            # In order to get the specific geometry type of the field,

            # we introspect on the table definition using `DESCRIBE`.

            cursor.execute('DESCRIBE %s' %

                           self.connection.ops.quote_name(table_name))

            # Increment over description info until we get to the geometry

            # column.

            for column, typ, null, key, default, extra in cursor.fetchall():

                if column == geo_col:

                    # Using OGRGeomType to convert from OGC name to Django field.

                    # MySQL does not support 3D or SRIDs, so the field params

                    # are empty.

                    field_type = OGRGeomType(typ).django

                    field_params = {}

                    break

        finally:

            cursor.close()

        return field_type, field_params