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# postgresql/pg8000.py
# Copyright (C) 2005-2017 the SQLAlchemy authors and contributors <see AUTHORS
# file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""
.. dialect:: postgresql+pg8000
:name: pg8000
:dbapi: pg8000
:connectstring: \
postgresql+pg8000://user:password@host:port/dbname[?key=value&key=value...]
:url: https://pythonhosted.org/pg8000/
.. _pg8000_unicode:
Unicode
-------
pg8000 will encode / decode string values between it and the server using the
PostgreSQL ``client_encoding`` parameter; by default this is the value in
the ``postgresql.conf`` file, which often defaults to ``SQL_ASCII``.
Typically, this can be changed to ``utf-8``, as a more useful default::
#client_encoding = sql_ascii # actually, defaults to database
# encoding
client_encoding = utf8
The ``client_encoding`` can be overridden for a session by executing the SQL:
SET CLIENT_ENCODING TO 'utf8';
SQLAlchemy will execute this SQL on all new connections based on the value
passed to :func:`.create_engine` using the ``client_encoding`` parameter::
engine = create_engine(
"postgresql+pg8000://user:pass@host/dbname", client_encoding='utf8')
.. _pg8000_isolation_level:
pg8000 Transaction Isolation Level
-------------------------------------
The pg8000 dialect offers the same isolation level settings as that
of the :ref:`psycopg2 <psycopg2_isolation_level>` dialect:
* ``READ COMMITTED``
* ``READ UNCOMMITTED``
* ``REPEATABLE READ``
* ``SERIALIZABLE``
* ``AUTOCOMMIT``
.. versionadded:: 0.9.5 support for AUTOCOMMIT isolation level when using
pg8000.
.. seealso::
:ref:`postgresql_isolation_level`
:ref:`psycopg2_isolation_level`
"""
from ... import util, exc
import decimal
from ... import processors
from ... import types as sqltypes
from .base import (
PGDialect, PGCompiler, PGIdentifierPreparer, PGExecutionContext,
_DECIMAL_TYPES, _FLOAT_TYPES, _INT_TYPES)
import re
from sqlalchemy.dialects.postgresql.json import JSON
class _PGNumeric(sqltypes.Numeric):
def result_processor(self, dialect, coltype):
if self.asdecimal:
if coltype in _FLOAT_TYPES:
return processors.to_decimal_processor_factory(
decimal.Decimal, self._effective_decimal_return_scale)
elif coltype in _DECIMAL_TYPES or coltype in _INT_TYPES:
# pg8000 returns Decimal natively for 1700
return None
else:
raise exc.InvalidRequestError(
"Unknown PG numeric type: %d" % coltype)
else:
if coltype in _FLOAT_TYPES:
# pg8000 returns float natively for 701
return None
elif coltype in _DECIMAL_TYPES or coltype in _INT_TYPES:
return processors.to_float
else:
raise exc.InvalidRequestError(
"Unknown PG numeric type: %d" % coltype)
class _PGNumericNoBind(_PGNumeric):
def bind_processor(self, dialect):
return None
class _PGJSON(JSON):
def result_processor(self, dialect, coltype):
if dialect._dbapi_version > (1, 10, 1):
return None # Has native JSON
else:
return super(_PGJSON, self).result_processor(dialect, coltype)
class PGExecutionContext_pg8000(PGExecutionContext):
pass
class PGCompiler_pg8000(PGCompiler):
def visit_mod_binary(self, binary, operator, **kw):
return self.process(binary.left, **kw) + " %% " + \
self.process(binary.right, **kw)
def post_process_text(self, text):
if '%%' in text:
util.warn("The SQLAlchemy postgresql dialect "
"now automatically escapes '%' in text() "
"expressions to '%%'.")
return text.replace('%', '%%')
class PGIdentifierPreparer_pg8000(PGIdentifierPreparer):
def _escape_identifier(self, value):
value = value.replace(self.escape_quote, self.escape_to_quote)
return value.replace('%', '%%')
class PGDialect_pg8000(PGDialect):
driver = 'pg8000'
supports_unicode_statements = True
supports_unicode_binds = True
default_paramstyle = 'format'
supports_sane_multi_rowcount = True
execution_ctx_cls = PGExecutionContext_pg8000
statement_compiler = PGCompiler_pg8000
preparer = PGIdentifierPreparer_pg8000
description_encoding = 'use_encoding'
colspecs = util.update_copy(
PGDialect.colspecs,
{
sqltypes.Numeric: _PGNumericNoBind,
sqltypes.Float: _PGNumeric,
JSON: _PGJSON,
sqltypes.JSON: _PGJSON
}
)
def __init__(self, client_encoding=None, **kwargs):
PGDialect.__init__(self, **kwargs)
self.client_encoding = client_encoding
def initialize(self, connection):
self.supports_sane_multi_rowcount = self._dbapi_version >= (1, 9, 14)
super(PGDialect_pg8000, self).initialize(connection)
@util.memoized_property
def _dbapi_version(self):
if self.dbapi and hasattr(self.dbapi, '__version__'):
return tuple(
[
int(x) for x in re.findall(
r'(\d+)(?:[-\.]?|$)', self.dbapi.__version__)])
else:
return (99, 99, 99)
@classmethod
def dbapi(cls):
return __import__('pg8000')
def create_connect_args(self, url):
opts = url.translate_connect_args(username='user')
if 'port' in opts:
opts['port'] = int(opts['port'])
opts.update(url.query)
return ([], opts)
def is_disconnect(self, e, connection, cursor):
return "connection is closed" in str(e)
def set_isolation_level(self, connection, level):
level = level.replace('_', ' ')
# adjust for ConnectionFairy possibly being present
if hasattr(connection, 'connection'):
connection = connection.connection
if level == 'AUTOCOMMIT':
connection.autocommit = True
elif level in self._isolation_lookup:
connection.autocommit = False
cursor = connection.cursor()
cursor.execute(
"SET SESSION CHARACTERISTICS AS TRANSACTION "
"ISOLATION LEVEL %s" % level)
cursor.execute("COMMIT")
cursor.close()
else:
raise exc.ArgumentError(
"Invalid value '%s' for isolation_level. "
"Valid isolation levels for %s are %s or AUTOCOMMIT" %
(level, self.name, ", ".join(self._isolation_lookup))
)
def set_client_encoding(self, connection, client_encoding):
# adjust for ConnectionFairy possibly being present
if hasattr(connection, 'connection'):
connection = connection.connection
cursor = connection.cursor()
cursor.execute("SET CLIENT_ENCODING TO '" + client_encoding + "'")
cursor.execute("COMMIT")
cursor.close()
def do_begin_twophase(self, connection, xid):
connection.connection.tpc_begin((0, xid, ''))
def do_prepare_twophase(self, connection, xid):
connection.connection.tpc_prepare()
def do_rollback_twophase(
self, connection, xid, is_prepared=True, recover=False):
connection.connection.tpc_rollback((0, xid, ''))
def do_commit_twophase(
self, connection, xid, is_prepared=True, recover=False):
connection.connection.tpc_commit((0, xid, ''))
def do_recover_twophase(self, connection):
return [row[1] for row in connection.connection.tpc_recover()]
def on_connect(self):
fns = []
if self.client_encoding is not None:
def on_connect(conn):
self.set_client_encoding(conn, self.client_encoding)
fns.append(on_connect)
if self.isolation_level is not None:
def on_connect(conn):
self.set_isolation_level(conn, self.isolation_level)
fns.append(on_connect)
if len(fns) > 0:
def on_connect(conn):
for fn in fns:
fn(conn)
return on_connect
else:
return None
dialect = PGDialect_pg8000
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