class DatabaseWrapper(WRAPPED_BACKEND.DatabaseWrapper):
def __init__(self, *args, **kwargs):
super(DatabaseWrapper, self).__init__(*args, **kwargs)
self.threadlocal = MultiTenantThreadlocal()
if not self.threadlocal.get_dbname():
self.threadlocal.set_dbname(self.settings_dict['NAME'])
def get_threadlocal(self):
return self.threadlocal
def _cursor(self):
"""Supplies a cursor, executing the `USE` statement if required.
Ideally we'd override a get_new_connection DatabaseWrapper function,
but _cursor() is as close as it gets.
"""
cursor = super(DatabaseWrapper, self)._cursor()
dbname = self.threadlocal.get_dbname()
if not dbname:
raise ImproperlyConfigured('dbname not set at cursor create time')
# Cache the applied dbname as "mt_dbname" on the connection, avoiding
# an extra execute() if already set. Importantly, we assume no other
# code in the app is executing `USE`.
connection = cursor.cursor.connection
connection_dbname = getattr(connection, 'mt_dbname', None)
if connection_dbname != dbname:
start_time = time.time()
cursor.execute('USE `%s`;' % dbname)
time_ms = int((time.time() - start_time) * 1000)
LOGGER.debug('Applied dbname `%s` in %s ms' % (dbname, time_ms))
connection.mt_dbname = dbname
return cursor
