可空插入缓存？ [英] Can null be inserted into Cache?

问题描述

我积极参与我的ASP.NET网站上使用缓存。

I actively use caching in my ASP.NET web site.

不过，从数据库请求某些对象真的是不存在的。举例来说，我检查，如果有一个折扣通过寻找纪录 =产品编号@产品编号特定产品在 ProductsDiscount 表。记录缺位意味着没有折扣。

Though, some objects requested from db are really absent. For instance, I'm checking if there is a Discount for the particular product by looking record with ProductId=@ProductId in ProductsDiscount table. Absence of the record means no discount.

你觉得这是一个好主意，把空优惠对象到缓存？

Do you think it is a good idea to put null discount objects into Cache?

或者，我会更好地创造更好的东西（使用空对象模式，例如）。其实，我真的不喜欢主意，开始使用空对象模式，因为这将需要大量的重新设计的，我想避免，至少现在。

Or I would better invent something better (using null-object pattern, for instance). In fact, I don't really like idea to start using null-object pattern as it will require a lot of redesign that I would like to avoid at least right now.

感谢。任何想法都欢迎。

Thanks. Any thoughts are welcome.

P.S。事实上，我甚至不能把空物体进入高速缓存，当我尝试拨打：

P.S. In fact, I can't even put null object into Cache, when I try to call:

HttpContext.Current.Cache.Insert("name...", null);

我收到：

值不能为空。

P.P.S。为什么MSDN不能说明这种行为？

P.P.S. Why MSDN tells nothing about this behavior?

推荐答案

有关你的情况，你可以使用 DBNull.Value 作为无数据标记：

For your case, you could use DBNull.Value as the 'no data' marker:

HttpContext.Current.Cache.Insert("name...", DBNull.Value);

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