queryset.py 文件源码

def _get_output(self, output):

        if isinstance(output, str) or isinstance(output, SON):
            out = output

        elif isinstance(output, dict):
            ordered_output = []
            for part in ('replace', 'merge', 'reduce'):
                value = output.get(part)
                if value:
                    ordered_output.append((part, value))
                    break

            else:
                raise OperationError("actionData not specified for output")

            db_alias = output.get('db_alias')
            remaing_args = ['db', 'sharded', 'nonAtomic']

            if db_alias:
                ordered_output.append(('db', get_db(db_alias).name))
                del remaing_args[0]

            for part in remaing_args:
                value = output.get(part)
                if value:
                    ordered_output.append((part, value))

            out = SON(ordered_output)

        else:
            raise ConfusionError('Bad output type %r'.format(type(output)))

        return out