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"""
PostgreSQL database backend for Django.
Requires psycopg 2: http://initd.org/projects/psycopg2
"""
from django.conf import settings
from django.db.backends import (BaseDatabaseFeatures, BaseDatabaseWrapper,
BaseDatabaseValidation)
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.db.backends.postgresql_psycopg2.schema import DatabaseSchemaEditor
from django.db.utils import InterfaceError
from django.utils.encoding import force_str
from django.utils.functional import cached_property
from django.utils.safestring import SafeText, SafeBytes
from django.utils.timezone import utc
try:
import psycopg2 as Database
import psycopg2.extensions
except ImportError as 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_type(psycopg2.extensions.UNICODEARRAY)
psycopg2.extensions.register_adapter(SafeBytes, psycopg2.extensions.QuotedString)
psycopg2.extensions.register_adapter(SafeText, psycopg2.extensions.QuotedString)
def utc_tzinfo_factory(offset):
if offset != 0:
raise AssertionError("database connection isn't set to UTC")
return utc
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
uses_savepoints = True
supports_tablespaces = True
supports_transactions = True
can_introspect_ip_address_field = True
can_introspect_small_integer_field = True
can_distinct_on_fields = True
can_rollback_ddl = True
supports_combined_alters = True
nulls_order_largest = True
closed_cursor_error_class = InterfaceError
has_case_insensitive_like = False
requires_sqlparse_for_splitting = False
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)',
}
pattern_ops = {
'startswith': "LIKE %s || '%%%%'",
'istartswith': "LIKE UPPER(%s) || '%%%%'",
}
Database = Database
def __init__(self, *args, **kwargs):
super(DatabaseWrapper, self).__init__(*args, **kwargs)
self.features = DatabaseFeatures(self)
self.ops = DatabaseOperations(self)
self.client = DatabaseClient(self)
self.creation = DatabaseCreation(self)
self.introspection = DatabaseIntrospection(self)
self.validation = BaseDatabaseValidation(self)
def get_connection_params(self):
settings_dict = self.settings_dict
# None may be used to connect to the default 'postgres' db
if settings_dict['NAME'] == '':
from django.core.exceptions import ImproperlyConfigured
raise ImproperlyConfigured(
"settings.DATABASES is improperly configured. "
"Please supply the NAME value.")
conn_params = {
'database': settings_dict['NAME'] or 'postgres',
}
conn_params.update(settings_dict['OPTIONS'])
if 'autocommit' in conn_params:
del conn_params['autocommit']
if 'isolation_level' in conn_params:
del conn_params['isolation_level']
if settings_dict['USER']:
conn_params['user'] = settings_dict['USER']
if settings_dict['PASSWORD']:
conn_params['password'] = force_str(settings_dict['PASSWORD'])
if settings_dict['HOST']:
conn_params['host'] = settings_dict['HOST']
if settings_dict['PORT']:
conn_params['port'] = settings_dict['PORT']
return conn_params
def get_new_connection(self, conn_params):
connection = Database.connect(**conn_params)
# self.isolation_level must be set:
# - after connecting to the database in order to obtain the database's
# default when no value is explicitly specified in options.
# - before calling _set_autocommit() because if autocommit is on, that
# will set connection.isolation_level to ISOLATION_LEVEL_AUTOCOMMIT;
# and if autocommit is off, on psycopg2 < 2.4.2, _set_autocommit()
# needs self.isolation_level.
options = self.settings_dict['OPTIONS']
try:
self.isolation_level = options['isolation_level']
except KeyError:
self.isolation_level = connection.isolation_level
else:
# Set the isolation level to the value from OPTIONS. This isn't
# needed on psycopg2 < 2.4.2 because it happens as a side-effect
# of _set_autocommit(False).
if (self.isolation_level != connection.isolation_level and
self.psycopg2_version >= (2, 4, 2)):
connection.set_session(isolation_level=self.isolation_level)
return connection
def init_connection_state(self):
settings_dict = self.settings_dict
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:
cursor = self.connection.cursor()
try:
cursor.execute(self.ops.set_time_zone_sql(), [tz])
finally:
cursor.close()
# Commit after setting the time zone (see #17062)
if not self.get_autocommit():
self.connection.commit()
def create_cursor(self):
cursor = self.connection.cursor()
cursor.tzinfo_factory = utc_tzinfo_factory if settings.USE_TZ else None
return cursor
def _set_isolation_level(self, isolation_level):
assert isolation_level in range(1, 5) # Use set_autocommit for level = 0
if self.psycopg2_version >= (2, 4, 2):
self.connection.set_session(isolation_level=isolation_level)
else:
self.connection.set_isolation_level(isolation_level)
def _set_autocommit(self, autocommit):
with self.wrap_database_errors:
if self.psycopg2_version >= (2, 4, 2):
self.connection.autocommit = autocommit
else:
if autocommit:
level = psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT
else:
level = self.isolation_level
self.connection.set_isolation_level(level)
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 is_usable(self):
try:
# Use a psycopg cursor directly, bypassing Django's utilities.
self.connection.cursor().execute("SELECT 1")
except Database.Error:
return False
else:
return True
def schema_editor(self, *args, **kwargs):
"Returns a new instance of this backend's SchemaEditor"
return DatabaseSchemaEditor(self, *args, **kwargs)
@cached_property
def psycopg2_version(self):
version = psycopg2.__version__.split(' ', 1)[0]
return tuple(int(v) for v in version.split('.'))
@cached_property
def pg_version(self):
with self.temporary_connection():
return get_version(self.connection)
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