#!/usr/bin/env python # -*- coding: utf-8 -*- ################################################################################ # # sqlalchemy-pervasive -- SQLAlchemy Dialect for Pervasive PSQL # Copyright © 2013 Sacramento Natural Foods Co-op, Inc # # This file is part of sqlalchemy-pervasive. # # sqlalchemy-pervasive is free software: you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by the # Free Software Foundation, either version 3 of the License, or (at your # option) any later version. # # sqlalchemy-pervasive is distributed in the hope that it will be useful, but # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY # or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for # more details. # # You should have received a copy of the GNU General Public License along with # sqlalchemy-pervasive. If not, see . # ################################################################################ """ Support for the Pervasive PSQL database engine. """ from sqlalchemy.sql.compiler import SQLCompiler from sqlalchemy.engine.default import DefaultDialect from sqlalchemy.exc import InvalidRequestError class PervasiveCompiler(SQLCompiler): """ Custom SQL statement compiler for Pervasive PSQL. """ def get_select_precolumns(self, select): # This logic was copied from the ``sqlalchemy-access`` dialect. s = 'DISTINCT ' if select._distinct else '' if select._limit: s += 'TOP {0} '.format(select._limit) if select._offset: raise InvalidRequestError( "Pervasive PSQL does not support limit with an offset") return s def limit_clause(self, select): return '' def visit_true(self, expr, **kw): return '1' def visit_false(self, expr, **kw): return '0' class PervasiveDialect(DefaultDialect): name = 'pervasive' statement_compiler = PervasiveCompiler