132 lines
4.8 KiB
Python
132 lines
4.8 KiB
Python
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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################################################################################
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#
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# SQLBase7-SA -- SQLAlchemy driver/dialect for Centura SQLBase v7
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# Copyright © 2010 Lance Edgar
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#
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# This file is part of SQLBase7-SA.
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#
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# SQLBase7-SA is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# SQLBase7-SA is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with SQLBase7-SA. If not, see <http://www.gnu.org/licenses/>.
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#
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################################################################################
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from sqlalchemy.engine.default import DefaultDialect
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from sqlalchemy import types, and_
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from sqlalchemy.sql.expression import Join
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import sqlalchemy
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from pkg_resources import parse_version
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if parse_version(sqlalchemy.__version__) <= parse_version('0.5.99'):
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from sqlalchemy.sql.compiler import DefaultCompiler as CompilerBase
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else:
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from sqlalchemy.sql.compiler import SQLCompiler as CompilerBase
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class LimitClauseNotSupported(Exception):
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def __init__(self, limit, offset):
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self.limit = limit
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self.offset = offset
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def __str__(self):
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return "Centura SQLBase 7.5.1 doesn't support a LIMIT clause for the SELECT statement (received: limit = %u, offset = %u)" % (self.limit, self.offset)
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class SQLBase7Compiler(CompilerBase):
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# Most of the code below was copied from the Oracle dialect. Thanks to Michael Bayer
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# for pointing that out. Oh, and for writing SQLAlchemy; that was pretty cool.
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def visit_join(self, join, **kwargs):
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kwargs['asfrom'] = True
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return self.process(join.left, **kwargs) + ", " + self.process(join.right, **kwargs)
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def visit_select(self, select, **kwargs):
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froms = select._get_display_froms()
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whereclause = self._get_join_whereclause(froms)
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if whereclause is not None:
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select = select.where(whereclause)
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if select._limit is not None or select._offset is not None:
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raise LimitClauseNotSupported(select._limit, select._offset)
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kwargs['iswrapper'] = getattr(select, '_is_wrapper', False)
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return super(SQLBase7Compiler, self).visit_select(select, **kwargs)
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def _get_join_whereclause(self, froms):
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clauses = []
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def visit_join(join):
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clauses.append(join.onclause)
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for j in join.left, join.right:
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if isinstance(j, Join):
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visit_join(j)
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for f in froms:
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if isinstance(f, Join):
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visit_join(f)
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if clauses:
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return and_(*clauses)
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return None
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class SQLBase7Dialect(DefaultDialect):
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name = 'sqlbase7'
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statement_compiler = SQLBase7Compiler
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max_identifier_length = 18
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_type_map = {
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'CHAR' : types.CHAR,
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'DATE' : types.DATE,
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'DECIMAL' : types.DECIMAL,
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'FLOAT' : types.FLOAT,
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'SMALLINT' : types.SMALLINT,
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'TIME' : types.TIME,
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'TIMESTMP' : types.TIMESTAMP,
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'VARCHAR' : types.VARCHAR,
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}
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def create_connect_args(self, url):
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connection_string = ';'.join((
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"DRIVER={Centura SQLBase 3.5 32-bit Driver -NT & Win95}",
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"SERVER=%s" % url.host,
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"DATABASE=%s" % url.database,
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"UID=%s" % url.username,
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"PWD=%s" % url.password,
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))
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return [connection_string], {}
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def get_default_schema_name(self, connection):
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return 'SYSADM'
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def do_execute(self, cursor, statement, parameters, context=None):
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# For some (perhaps good?) reason, the SQLBase ODBC driver doesn't like
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# parameters if they're of Unicode or Long type. I'd hoped at first that
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# the "supports_unicode_binds" attribute would take care of the Unicode
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# problem but it didn't seem to. And now the Long parameters seem to
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# throw the same error, so...
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parameters = list(parameters)
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for i, parameter in enumerate(parameters):
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if isinstance(parameter, unicode):
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parameters[i] = str(parameter)
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elif isinstance(parameter, long):
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parameters[i] = int(parameter)
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super(SQLBase7Dialect, self).do_execute(cursor, statement, tuple(parameters), context)
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