base.py 文件源码

def _nodb_connection(self):
        nodb_connection = super(DatabaseWrapper, self)._nodb_connection
        try:
            nodb_connection.ensure_connection()
        except (Database.DatabaseError, WrappedDatabaseError):
            warnings.warn(
                "Normally Django will use a connection to the 'postgres' database "
                "to avoid running initialization queries against the production "
                "database when it's not needed (for example, when running tests). "
                "Django was unable to create a connection to the 'postgres' database "
                "and will use the default database instead.",
                RuntimeWarning
            )
            settings_dict = self.settings_dict.copy()
            settings_dict['NAME'] = settings.DATABASES[DEFAULT_DB_ALIAS]['NAME']
            nodb_connection = self.__class__(
                self.settings_dict.copy(),
                alias=self.alias,
                allow_thread_sharing=False)
        return nodb_connection