LINQ to SQL and Null strings, how do I use Contains?

Question

Here is the query

from a in this._addresses where a.Street.Contains(street) || a.StreetAdditional.Contains(streetAdditional) select a).ToList<Address>() 

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.

Is there a work around this?

Thanks,

Answer 1

I'd use the null-coalescing operator...

(from a in this._addresses where (a.Street ?? "").Contains(street) || (a.StreetAdditional ?? "").Contains(streetAdditional) select a).ToList<Address>() 

Answer 2

The most obvious one:

from a in this._addresses where (a.Street != null && a.Street.Contains(street)) || (a.StreetAdditional != null && a.StreetAdditional.Contains(streetAdditional)) select a).ToList<Address>() 

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).