Files
pretix_original/src/pretix/helpers/database.py
2021-05-07 12:00:30 +02:00

106 lines
3.5 KiB
Python

#
# This file is part of pretix (Community Edition).
#
# Copyright (C) 2014-2020 Raphael Michel and contributors
# Copyright (C) 2020-2021 rami.io GmbH and contributors
#
# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
# Public License as published by the Free Software Foundation in version 3 of the License.
#
# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
# this file, see <https://pretix.eu/about/en/license>.
#
# This program 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 Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along with this program. If not, see
# <https://www.gnu.org/licenses/>.
#
import contextlib
from django.db import transaction
from django.db.models import Aggregate, Field, Lookup
class DummyRollbackException(Exception):
pass
@contextlib.contextmanager
def rolledback_transaction():
"""
This context manager runs your code in a database transaction that will be rolled back in the end.
This can come in handy to simulate the effects of a database operation that you do not actually
want to perform.
Note that rollbacks are a very slow operation on most database backends. Also, long-running
transactions can slow down other operations currently running and you should not use this
in a place that is called frequently.
"""
try:
with transaction.atomic():
yield
raise DummyRollbackException()
except DummyRollbackException:
pass
else:
raise Exception('Invalid state, should have rolled back.')
@contextlib.contextmanager
def casual_reads():
"""
Kept for backwards compatibility.
"""
yield
class GroupConcat(Aggregate):
function = 'group_concat'
template = '%(function)s(%(field)s, "%(separator)s")'
def __init__(self, *expressions, **extra):
if 'separator' not in extra:
# For PostgreSQL separator is an obligatory
extra.update({'separator': ','})
super().__init__(*expressions, **extra)
def as_postgresql(self, compiler, connection):
return super().as_sql(
compiler, connection,
function='string_agg',
template="%(function)s(%(field)s::text, '%(separator)s')",
)
class ReplicaRouter:
def db_for_read(self, model, **hints):
return 'default'
def db_for_write(self, model, **hints):
return 'default'
def allow_relation(self, obj1, obj2, **hints):
db_list = ('default', 'replica')
if obj1._state.db in db_list and obj2._state.db in db_list:
return True
return None
def allow_migrate(self, db, app_label, model_name=None, **hintrs):
return True
@Field.register_lookup
class NotEqual(Lookup):
lookup_name = 'ne'
def as_sql(self, compiler, connection):
lhs, lhs_params = self.process_lhs(compiler, connection)
rhs, rhs_params = self.process_rhs(compiler, connection)
params = lhs_params + rhs_params
return '%s <> %s' % (lhs, rhs), params