问题描述
这里是查询
from a in this._addresses
where a.Street.Contains(street) || a.StreetAdditional.Contains(streetAdditional)
select a).ToList<Address>()
如果 where 子句中的两个属性都有值，这可以正常工作，但例如，如果 a.StreetAdditional 为空(大多数情况下)，我将收到空引用异常.
if both properties in the where clause have values this works fine, but if for example, a.StreetAdditional is null (Most of the times), I will get a null reference exception.
有办法解决这个问题吗?
Is there a work around this?
谢谢，
推荐答案
最明显的一个:
from a in this._addresses
where (a.Street != null && a.Street.Contains(street)) || (a.StreetAdditional != null && a.StreetAdditional.Contains(streetAdditional))
select a).ToList<Address>()
或者，您可以为 Contains 编写一个扩展方法，该方法接受空参数而不会出错.有人可能会说，有这样的方法不是很好，因为它看起来像一个普通的方法调用，但允许有空值(从而搁置正常的空检查实践).
Alternatively you could write an extension method for Contains that accepts a null argument without error. Some might say that it is not so pretty to have such a method, because it looks like a normal method call, but is allowed for null values (thereby setting aside normal null-checking practices).
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