# access.py
# Copyright (C) 2007 Paul Johnston, paj@pajhome.org.uk
# Portions derived from jet2sql.py by Matt Keranen, mksql@yahoo.com
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""
Support for the Microsoft Access database.
This dialect is *not* ported to SQLAlchemy 0.6.
This dialect is *not* tested on SQLAlchemy 0.6.
"""
from sqlalchemy import sql,schema,types,exc,pool
from sqlalchemy.sql import compiler,expression
from sqlalchemy.engine import default,base,reflection
from sqlalchemy import processors
class AcNumeric(types.Numeric):
def get_col_spec(self):
return "NUMERIC"
def bind_processor(self, dialect):
return processors.to_str
def result_processor(self, dialect, coltype):
return None
class AcFloat(types.Float):
def get_col_spec(self):
return "FLOAT"
def bind_processor(self, dialect):
"""By converting to string, we can use Decimal types round-trip."""
return processors.to_str
class AcInteger(types.Integer):
def get_col_spec(self):
return "INTEGER"
class AcTinyInteger(types.Integer):
def get_col_spec(self):
return "TINYINT"
class AcSmallInteger(types.SmallInteger):
def get_col_spec(self):
return "SMALLINT"
class AcDateTime(types.DateTime):
def __init__(self, *a, **kw):
super(AcDateTime, self).__init__(False)
def get_col_spec(self):
return "DATETIME"
class AcDate(types.Date):
def __init__(self, *a, **kw):
super(AcDate, self).__init__(False)
def get_col_spec(self):
return "DATETIME"
class AcText(types.Text):
def get_col_spec(self):
return "MEMO"
class AcString(types.String):
def get_col_spec(self):
return "TEXT" + (self.length and ("(%d)" % self.length) or "")
class AcUnicode(types.Unicode):
def get_col_spec(self):
return "TEXT" + (self.length and ("(%d)" % self.length) or "")
def bind_processor(self, dialect):
return None
def result_processor(self, dialect, coltype):
return None
class AcChar(types.CHAR):
def get_col_spec(self):
return "TEXT" + (self.length and ("(%d)" % self.length) or "")
class AcBinary(types.LargeBinary):
def get_col_spec(self):
return "BINARY"
class AcBoolean(types.Boolean):
def get_col_spec(self):
return "YESNO"
class AcTimeStamp(types.TIMESTAMP):
def get_col_spec(self):
return "TIMESTAMP"
class AccessExecutionContext(default.DefaultExecutionContext):
def _has_implicit_sequence(self, column):
if column.primary_key and column.autoincrement:
if isinstance(column.type, types.Integer) and not column.foreign_keys:
if column.default is None or (isinstance(column.default, schema.Sequence) and \
column.default.optional):
return True
return False
def post_exec(self):
"""If we inserted into a row with a COUNTER column, fetch the ID"""
if self.compiled.isinsert:
tbl = self.compiled.statement.table
if not hasattr(tbl, 'has_sequence'):
tbl.has_sequence = None
for column in tbl.c:
if getattr(column, 'sequence', False) or self._has_implicit_sequence(column):
tbl.has_sequence = column
break
if bool(tbl.has_sequence):
# TBD: for some reason _last_inserted_ids doesn't exist here
# (but it does at corresponding point in mssql???)
#if not len(self._last_inserted_ids) or self._last_inserted_ids[0] is None:
self.cursor.execute("SELECT @@identity AS lastrowid")
row = self.cursor.fetchone()
self._last_inserted_ids = [int(row[0])] #+ self._last_inserted_ids[1:]
# print "LAST ROW ID", self._last_inserted_ids
super(AccessExecutionContext, self).post_exec()
const, daoEngine = None, None
class AccessDialect(default.DefaultDialect):
colspecs = {
types.Unicode : AcUnicode,
types.Integer : AcInteger,
types.SmallInteger: AcSmallInteger,
types.Numeric : AcNumeric,
types.Float : AcFloat,
types.DateTime : AcDateTime,
types.Date : AcDate,
types.String : AcString,
types.LargeBinary : AcBinary,
types.Boolean : AcBoolean,
types.Text : AcText,
types.CHAR: AcChar,
types.TIMESTAMP: AcTimeStamp,
}
name = 'access'
supports_sane_rowcount = False
supports_sane_multi_rowcount = False
ported_sqla_06 = False
def type_descriptor(self, typeobj):
newobj = types.adapt_type(typeobj, self.colspecs)
return newobj
def __init__(self, **params):
super(AccessDialect, self).__init__(**params)
self.text_as_varchar = False
self._dtbs = None
def dbapi(cls):
import win32com.client, pythoncom
global const, daoEngine
if const is None:
const = win32com.client.constants
for suffix in (".36", ".35", ".30"):
try:
daoEngine = win32com.client.gencache.EnsureDispatch("DAO.DBEngine" + suffix)
break
except pythoncom.com_error:
pass
else:
raise exc.InvalidRequestError("Can't find a DB engine. Check http://support.microsoft.com/kb/239114 for details.")
import pyodbc as module
return module
dbapi = classmethod(dbapi)
def create_connect_args(self, url):
opts = url.translate_connect_args()
connectors = ["Driver={Microsoft Access Driver (*.mdb)}"]
connectors.append("Dbq=%s" % opts["database"])
user = opts.get("username", None)
if user:
connectors.append("UID=%s" % user)
connectors.append("PWD=%s" % opts.get("password", ""))
return [[";".join(connectors)], {}]
def last_inserted_ids(self):
return self.context.last_inserted_ids
def do_execute(self, cursor, statement, params, **kwargs):
if params == {}:
params = ()
super(AccessDialect, self).do_execute(cursor, statement, params, **kwargs)
def _execute(self, c, statement, parameters):
try:
if parameters == {}:
parameters = ()
c.execute(statement, parameters)
self.context.rowcount = c.rowcount
except Exception, e:
raise exc.DBAPIError.instance(statement, parameters, e)
def has_table(self, connection, tablename, schema=None):
# This approach seems to be more reliable that using DAO
try:
connection.execute('select top 1 * from [%s]' % tablename)
return True
except Exception, e:
return False
def reflecttable(self, connection, table, include_columns):
# This is defined in the function, as it relies on win32com constants,
# that aren't imported until dbapi method is called
if not hasattr(self, 'ischema_names'):
self.ischema_names = {
const.dbByte: AcBinary,
const.dbInteger: AcInteger,
const.dbLong: AcInteger,
const.dbSingle: AcFloat,
const.dbDouble: AcFloat,
const.dbDate: AcDateTime,
const.dbLongBinary: AcBinary,
const.dbMemo: AcText,
const.dbBoolean: AcBoolean,
const.dbText: AcUnicode, # All Access strings are unicode
const.dbCurrency: AcNumeric,
}
# A fresh DAO connection is opened for each reflection
# This is necessary, so we get the latest updates
dtbs = daoEngine.OpenDatabase(connection.engine.url.database)
try:
for tbl in dtbs.TableDefs:
if tbl.Name.lower() == table.name.lower():
break
else:
raise exc.NoSuchTableError(table.name)
for col in tbl.Fields:
coltype = self.ischema_names[col.Type]
if col.Type == const.dbText:
coltype = coltype(col.Size)
colargs = \
{
'nullable': not(col.Required or col.Attributes & const.dbAutoIncrField),
}
default = col.DefaultValue
if col.Attributes & const.dbAutoIncrField:
colargs['default'] = schema.Sequence(col.Name + '_seq')
elif default:
if col.Type == const.dbBoolean:
default = default == 'Yes' and '1' or '0'
colargs['server_default'] = schema.DefaultClause(sql.text(default))
table.append_column(schema.Column(col.Name, coltype, **colargs))
# TBD: check constraints
# Find primary key columns first
for idx in tbl.Indexes:
if idx.Primary:
for col in idx.Fields:
thecol = table.c[col.Name]
table.primary_key.add(thecol)
if isinstance(thecol.type, AcInteger) and \
not (thecol.default and isinstance(thecol.default.arg, schema.Sequence)):
thecol.autoincrement = False
# Then add other indexes
for idx in tbl.Indexes:
if not idx.Primary:
if len(idx.Fields) == 1:
col = table.c[idx.Fields[0].Name]
if not col.primary_key:
col.index = True
col.unique = idx.Unique
else:
pass # TBD: multi-column indexes
for fk in dtbs.Relations:
if fk.ForeignTable != table.name:
continue
scols = [c.ForeignName for c in fk.Fields]
rcols = ['%s.%s' % (fk.Table, c.Name) for c in fk.Fields]
table.append_constraint(schema.ForeignKeyConstraint(scols, rcols, link_to_name=True))
finally:
dtbs.Close()
@reflection.cache
def get_table_names(self, connection, schema=None, **kw):
# A fresh DAO connection is opened for each reflection
# This is necessary, so we get the latest updates
dtbs = daoEngine.OpenDatabase(connection.engine.url.database)
names = [t.Name for t in dtbs.TableDefs if t.Name[:4] != "MSys" and t.Name[:4] != "~TMP"]
dtbs.Close()
return names
class AccessCompiler(compiler.SQLCompiler):
extract_map = compiler.SQLCompiler.extract_map.copy()
extract_map.update ({
'month': 'm',
'day': 'd',
'year': 'yyyy',
'second': 's',
'hour': 'h',
'doy': 'y',
'minute': 'n',
'quarter': 'q',
'dow': 'w',
'week': 'ww'
})
def visit_select_precolumns(self, select):
"""Access puts TOP, it's version of LIMIT here """
s = select.distinct and "DISTINCT " or ""
if select.limit:
s += "TOP %s " % (select.limit)
if select.offset:
raise exc.InvalidRequestError('Access does not support LIMIT with an offset')
return s
def limit_clause(self, select):
"""Limit in access is after the select keyword"""
return ""
def binary_operator_string(self, binary):
"""Access uses "mod" instead of "%" """
return binary.operator == '%' and 'mod' or binary.operator
def label_select_column(self, select, column, asfrom):
if isinstance(column, expression.Function):
return column.label()
else:
return super(AccessCompiler, self).label_select_column(select, column, asfrom)
function_rewrites = {'current_date': 'now',
'current_timestamp': 'now',
'length': 'len',
}
def visit_function(self, func):
"""Access function names differ from the ANSI SQL names; rewrite common ones"""
func.name = self.function_rewrites.get(func.name, func.name)
return super(AccessCompiler, self).visit_function(func)
def for_update_clause(self, select):
"""FOR UPDATE is not supported by Access; silently ignore"""
return ''
# Strip schema
def visit_table(self, table, asfrom=False, **kwargs):
if asfrom:
return self.preparer.quote(table.name, table.quote)
else:
return ""
def visit_join(self, join, asfrom=False, **kwargs):
return (self.process(join.left, asfrom=True) + (join.isouter and " LEFT OUTER JOIN " or " INNER JOIN ") + \
self.process(join.right, asfrom=True) + " ON " + self.process(join.onclause))
def visit_extract(self, extract, **kw):
field = self.extract_map.get(extract.field, extract.field)
return 'DATEPART("%s", %s)' % (field, self.process(extract.expr, **kw))
class AccessDDLCompiler(compiler.DDLCompiler):
def get_column_specification(self, column, **kwargs):
colspec = self.preparer.format_column(column) + " " + column.type.dialect_impl(self.dialect).get_col_spec()
# install a sequence if we have an implicit IDENTITY column
if (not getattr(column.table, 'has_sequence', False)) and column.primary_key and \
column.autoincrement and isinstance(column.type, types.Integer) and not column.foreign_keys:
if column.default is None or (isinstance(column.default, schema.Sequence) and column.default.optional):
column.sequence = schema.Sequence(column.name + '_seq')
if not column.nullable:
colspec += " NOT NULL"
if hasattr(column, 'sequence'):
column.table.has_sequence = column
colspec = self.preparer.format_column(column) + " counter"
else:
default = self.get_column_default_string(column)
if default is not None:
colspec += " DEFAULT " + default
return colspec
def visit_drop_index(self, drop):
index = drop.element
self.append("\nDROP INDEX [%s].[%s]" % (index.table.name, self._validate_identifier(index.name, False)))
class AccessIdentifierPreparer(compiler.IdentifierPreparer):
reserved_words = compiler.RESERVED_WORDS.copy()
reserved_words.update(['value', 'text'])
def __init__(self, dialect):
super(AccessIdentifierPreparer, self).__init__(dialect, initial_quote='[', final_quote=']')
dialect = AccessDialect
dialect.poolclass = pool.SingletonThreadPool
dialect.statement_compiler = AccessCompiler
dialect.ddlcompiler = AccessDDLCompiler
dialect.preparer = AccessIdentifierPreparer
dialect.execution_ctx_cls = AccessExecutionContext
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