/
base.py
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/
base.py
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"""
PostgreSQL database backend for Django.
Requires psycopg 2: http://initd.org/projects/psycopg2
"""
import sys
from django.db import utils
from django.db.backends import *
from django.db.backends.signals import connection_created
from django.db.backends.postgresql_psycopg2.operations import DatabaseOperations
from django.db.backends.postgresql_psycopg2.client import DatabaseClient
from django.db.backends.postgresql_psycopg2.creation import DatabaseCreation
from django.db.backends.postgresql_psycopg2.version import get_version
from django.db.backends.postgresql_psycopg2.introspection import DatabaseIntrospection
from django.utils.log import getLogger
from django.utils.safestring import SafeUnicode, SafeString
from django.utils.timezone import utc
try:
import psycopg2 as Database
import psycopg2.extensions
except ImportError, e:
from django.core.exceptions import ImproperlyConfigured
raise ImproperlyConfigured("Error loading psycopg2 module: %s" % e)
DatabaseError = Database.DatabaseError
IntegrityError = Database.IntegrityError
psycopg2.extensions.register_type(psycopg2.extensions.UNICODE)
psycopg2.extensions.register_adapter(SafeString, psycopg2.extensions.QuotedString)
psycopg2.extensions.register_adapter(SafeUnicode, psycopg2.extensions.QuotedString)
logger = getLogger('django.db.backends')
def utc_tzinfo_factory(offset):
if offset != 0:
raise AssertionError("database connection isn't set to UTC")
return utc
class CursorWrapper(object):
"""
A thin wrapper around psycopg2's normal cursor class so that we can catch
particular exception instances and reraise them with the right types.
"""
def __init__(self, cursor):
self.cursor = cursor
def execute(self, query, args=None):
try:
return self.cursor.execute(query, args)
except Database.IntegrityError, e:
raise utils.IntegrityError, utils.IntegrityError(*tuple(e)), sys.exc_info()[2]
except Database.DatabaseError, e:
raise utils.DatabaseError, utils.DatabaseError(*tuple(e)), sys.exc_info()[2]
def executemany(self, query, args):
try:
return self.cursor.executemany(query, args)
except Database.IntegrityError, e:
raise utils.IntegrityError, utils.IntegrityError(*tuple(e)), sys.exc_info()[2]
except Database.DatabaseError, e:
raise utils.DatabaseError, utils.DatabaseError(*tuple(e)), sys.exc_info()[2]
def __getattr__(self, attr):
if attr in self.__dict__:
return self.__dict__[attr]
else:
return getattr(self.cursor, attr)
def __iter__(self):
return iter(self.cursor)
class DatabaseFeatures(BaseDatabaseFeatures):
needs_datetime_string_cast = False
can_return_id_from_insert = True
requires_rollback_on_dirty_transaction = True
has_real_datatype = True
can_defer_constraint_checks = True
has_select_for_update = True
has_select_for_update_nowait = True
has_bulk_insert = True
supports_tablespaces = True
can_distinct_on_fields = True
class DatabaseWrapper(BaseDatabaseWrapper):
vendor = 'postgresql'
operators = {
'exact': '= %s',
'iexact': '= UPPER(%s)',
'contains': 'LIKE %s',
'icontains': 'LIKE UPPER(%s)',
'regex': '~ %s',
'iregex': '~* %s',
'gt': '> %s',
'gte': '>= %s',
'lt': '< %s',
'lte': '<= %s',
'startswith': 'LIKE %s',
'endswith': 'LIKE %s',
'istartswith': 'LIKE UPPER(%s)',
'iendswith': 'LIKE UPPER(%s)',
}
def __init__(self, *args, **kwargs):
super(DatabaseWrapper, self).__init__(*args, **kwargs)
self.features = DatabaseFeatures(self)
autocommit = self.settings_dict["OPTIONS"].get('autocommit', False)
self.features.uses_autocommit = autocommit
if autocommit:
level = psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT
else:
level = psycopg2.extensions.ISOLATION_LEVEL_READ_COMMITTED
self._set_isolation_level(level)
self.ops = DatabaseOperations(self)
self.client = DatabaseClient(self)
self.creation = DatabaseCreation(self)
self.introspection = DatabaseIntrospection(self)
self.validation = BaseDatabaseValidation(self)
self._pg_version = None
def check_constraints(self, table_names=None):
"""
To check constraints, we set constraints to immediate. Then, when, we're done we must ensure they
are returned to deferred.
"""
self.cursor().execute('SET CONSTRAINTS ALL IMMEDIATE')
self.cursor().execute('SET CONSTRAINTS ALL DEFERRED')
def close(self):
self.validate_thread_sharing()
if self.connection is None:
return
try:
self.connection.close()
self.connection = None
except Database.Error:
# In some cases (database restart, network connection lost etc...)
# the connection to the database is lost without giving Django a
# notification. If we don't set self.connection to None, the error
# will occur a every request.
self.connection = None
logger.warning('psycopg2 error while closing the connection.',
exc_info=sys.exc_info()
)
raise
def _get_pg_version(self):
if self._pg_version is None:
self._pg_version = get_version(self.connection)
return self._pg_version
pg_version = property(_get_pg_version)
def _cursor(self):
settings_dict = self.settings_dict
if self.connection is None:
if settings_dict['NAME'] == '':
from django.core.exceptions import ImproperlyConfigured
raise ImproperlyConfigured("You need to specify NAME in your Django settings file.")
conn_params = {
'database': settings_dict['NAME'],
}
conn_params.update(settings_dict['OPTIONS'])
if 'autocommit' in conn_params:
del conn_params['autocommit']
if settings_dict['USER']:
conn_params['user'] = settings_dict['USER']
if settings_dict['PASSWORD']:
conn_params['password'] = settings_dict['PASSWORD']
if settings_dict['HOST']:
conn_params['host'] = settings_dict['HOST']
if settings_dict['PORT']:
conn_params['port'] = settings_dict['PORT']
self.connection = Database.connect(**conn_params)
self.connection.set_client_encoding('UTF8')
tz = 'UTC' if settings.USE_TZ else settings_dict.get('TIME_ZONE')
if tz:
try:
get_parameter_status = self.connection.get_parameter_status
except AttributeError:
# psycopg2 < 2.0.12 doesn't have get_parameter_status
conn_tz = None
else:
conn_tz = get_parameter_status('TimeZone')
if conn_tz != tz:
# Set the time zone in autocommit mode (see #17062)
self.connection.set_isolation_level(
psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT)
self.connection.cursor().execute(
self.ops.set_time_zone_sql(), [tz])
self.connection.set_isolation_level(self.isolation_level)
self._get_pg_version()
connection_created.send(sender=self.__class__, connection=self)
cursor = self.connection.cursor()
cursor.tzinfo_factory = utc_tzinfo_factory if settings.USE_TZ else None
return CursorWrapper(cursor)
def _enter_transaction_management(self, managed):
"""
Switch the isolation level when needing transaction support, so that
the same transaction is visible across all the queries.
"""
if self.features.uses_autocommit and managed and not self.isolation_level:
self._set_isolation_level(psycopg2.extensions.ISOLATION_LEVEL_READ_COMMITTED)
def _leave_transaction_management(self, managed):
"""
If the normal operating mode is "autocommit", switch back to that when
leaving transaction management.
"""
if self.features.uses_autocommit and not managed and self.isolation_level:
self._set_isolation_level(psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT)
def _set_isolation_level(self, level):
"""
Do all the related feature configurations for changing isolation
levels. This doesn't touch the uses_autocommit feature, since that
controls the movement *between* isolation levels.
"""
assert level in range(5)
try:
if self.connection is not None:
self.connection.set_isolation_level(level)
finally:
self.isolation_level = level
self.features.uses_savepoints = bool(level)
def _commit(self):
if self.connection is not None:
try:
return self.connection.commit()
except Database.IntegrityError, e:
raise utils.IntegrityError, utils.IntegrityError(*tuple(e)), sys.exc_info()[2]