Django用动态值注释

嗨，在我的模型中，我的属性完全在缓存中，而不是在数据库中

class Model(models.Model):
    
    ....

    @property
    def _get_last_seen_cache_name(self) -> str:
        return f'{self.hostname.upper()}_last_seen'

    @property
    def last_seen(self) -> datetime | None:
        cached = cache.get(self._get_last_seen_cache_name, None)
        if isinstance(cached, datetime):
            return cached
        return None

    def update_last_seen(self) -> None:
        cache.set(self._get_last_seen_cache_name, get_now().replace(microsecond=0), None)

如何使用这个值last_seenqueryset进行注释。希望在管理页面中对该列进行排序。但为此，我需要从注释的缓存中获取值，使用正确的键名执行cache.get()

queryset = super().get_queryset(request)
queryset = queryset.annotate(last_seen=Value(cache.get(Concat('hostname', Value('_last_seen')))), CharField()))

或

queryset = queryset.annotate(last_seen=Value(cache.get(f"{F('hostname')_last_seen}")), CharField()))

I can annotate with literal value, but how annotate with dynamic value, that doesnt exist in database, but in cache 或 in mem或y only? How to do hostname substitution in a function?