def _db_type_for_alter_column(self, field):
        try:
            return field.db_type(connection=self._get_connection())
        except TypeError:
            return field.db_type()
Returns a field's type suitable for ALTER COLUMN.
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/South-1.0.2/south/db/generic.py/DatabaseOperations._db_type_for_alter_column