Added support for SA 0.5 (previously only 0.6 was supported).

sqlbase7_sa/sqlbase7.py

@@ -0,0 +1,132 @@
+#!/usr/bin/env python
+# -*- coding: utf-8  -*-
+################################################################################
+#
+#  SQLBase7-SA -- SQLAlchemy driver/dialect for Centura SQLBase v7
+#  Copyright © 2010 Lance Edgar
+#
+#  This file is part of SQLBase7-SA.
+#
+#  SQLBase7-SA 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.
+#
+#  SQLBase7-SA 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 SQLBase7-SA.  If not, see <http://www.gnu.org/licenses/>.
+#
+################################################################################
+
+
+from sqlalchemy.engine.default import DefaultDialect
+from sqlalchemy import types, and_
+from sqlalchemy.sql.expression import Join
+
+
+import sqlalchemy
+from pkg_resources import parse_version
+if parse_version(sqlalchemy.__version__) <= parse_version('0.5.99'):
+    from sqlalchemy.sql.compiler import DefaultCompiler as CompilerBase
+else:
+    from sqlalchemy.sql.compiler import SQLCompiler as CompilerBase
+
+
+class LimitClauseNotSupported(Exception):
+
+    def __init__(self, limit, offset):
+        self.limit = limit
+        self.offset = offset
+
+    def __str__(self):
+        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)
+
+
+class SQLBase7Compiler(CompilerBase):
+
+    # Most of the code below was copied from the Oracle dialect.  Thanks to Michael Bayer
+    # for pointing that out.  Oh, and for writing SQLAlchemy; that was pretty cool.
+
+    def visit_join(self, join, **kwargs):
+        kwargs['asfrom'] = True
+        return self.process(join.left, **kwargs) + ", " + self.process(join.right, **kwargs)
+
+    def visit_select(self, select, **kwargs):
+        froms = select._get_display_froms()
+        whereclause = self._get_join_whereclause(froms)
+        if whereclause is not None:
+            select = select.where(whereclause)
+
+        if select._limit is not None or select._offset is not None:
+            raise LimitClauseNotSupported(select._limit, select._offset)
+
+        kwargs['iswrapper'] = getattr(select, '_is_wrapper', False)
+        return super(SQLBase7Compiler, self).visit_select(select, **kwargs)
+
+    def _get_join_whereclause(self, froms):
+        clauses = []
+
+        def visit_join(join):
+            clauses.append(join.onclause)
+            for j in join.left, join.right:
+                if isinstance(j, Join):
+                    visit_join(j)
+                
+        for f in froms:
+            if isinstance(f, Join):
+                visit_join(f)
+
+        if clauses:
+            return and_(*clauses)
+        return None
+
+
+class SQLBase7Dialect(DefaultDialect):
+    
+    name = 'sqlbase7'
+
+    statement_compiler = SQLBase7Compiler
+
+    max_identifier_length = 18
+
+    _type_map = {
+        'CHAR'          : types.CHAR,
+        'DATE'          : types.DATE,
+        'DECIMAL'       : types.DECIMAL,
+        'FLOAT'         : types.FLOAT,
+        'SMALLINT'      : types.SMALLINT,
+        'TIME'          : types.TIME,
+        'TIMESTMP'      : types.TIMESTAMP,
+        'VARCHAR'       : types.VARCHAR,
+        }
+
+    def create_connect_args(self, url):
+        connection_string = ';'.join((
+                "DRIVER={Centura SQLBase 3.5 32-bit Driver -NT & Win95}",
+                "SERVER=%s" % url.host,
+                "DATABASE=%s" % url.database,
+                "UID=%s" % url.username,
+                "PWD=%s" % url.password,
+                ))
+        return [connection_string], {}
+
+    def get_default_schema_name(self, connection):
+        return 'SYSADM'
+    
+    def do_execute(self, cursor, statement, parameters, context=None):
+        # For some (perhaps good?) reason, the SQLBase ODBC driver doesn't like
+        # parameters if they're of Unicode or Long type.  I'd hoped at first that
+        # the "supports_unicode_binds" attribute would take care of the Unicode
+        # problem but it didn't seem to.  And now the Long parameters seem to
+        # throw the same error, so...
+        parameters = list(parameters)
+        for i, parameter in enumerate(parameters):
+            if isinstance(parameter, unicode):
+                parameters[i] = str(parameter)
+            elif isinstance(parameter, long):
+                parameters[i] = int(parameter)
+        super(SQLBase7Dialect, self).do_execute(cursor, statement, tuple(parameters), context)