forked from CGM_Public/pretix_original
79 lines
2.5 KiB
Python
79 lines
2.5 KiB
Python
import contextlib
|
|
|
|
from django.db import transaction
|
|
from django.db.models import Aggregate
|
|
from django.db.models.expressions import OrderBy
|
|
|
|
|
|
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 FixedOrderBy(OrderBy):
|
|
# Workaround for https://code.djangoproject.com/ticket/28848
|
|
template = '%(expression)s %(ordering)s'
|
|
|
|
def as_sql(self, compiler, connection, template=None, **extra_context):
|
|
if not template:
|
|
if self.nulls_last:
|
|
template = '%s NULLS LAST' % self.template
|
|
elif self.nulls_first:
|
|
template = '%s NULLS FIRST' % self.template
|
|
connection.ops.check_expression_support(self)
|
|
expression_sql, params = compiler.compile(self.expression)
|
|
placeholders = {
|
|
'expression': expression_sql,
|
|
'ordering': 'DESC' if self.descending else 'ASC',
|
|
}
|
|
placeholders.update(extra_context)
|
|
template = template or self.template
|
|
params = params * template.count('%(expression)s')
|
|
return (template % placeholders).rstrip(), params
|
|
|
|
|
|
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')",
|
|
)
|