Comments on: LINQ, SingleOrDefault and NullObject

By: guest

guest — Mon, 22 Jun 2009 17:42:50 +0000

doesn’t this work:

samples
.Where(o => o.Name == “someother”)
.DefaultIfEmpty(MyObject.NullValue)
.Single()
.Greet();

By: Thomas Watson

Thomas Watson — Mon, 12 Jan 2009 14:12:43 +0000

Not sure how to post code here, because that didnt work! I will try this:

” public static TSource SingleOrEmpty(this IEnumerable source, Func predicate)
{
var myNullObject = (TSource)Activator.CreateInstance(typeof(TSource));
var myResult = source.SingleOrDefault(predicate);
return myResult == null ? myNullObject : myResult;
}”

By: Thomas Watson

Thomas Watson — Mon, 12 Jan 2009 14:06:31 +0000

Hey, thanks for th start. Its annoying to have to create null objects this way, so I thought I would extend it with reflection:

public static TSource SingleOrEmpty(this IEnumerable source, Func predicate)
{
var myNullObject = (TSource)Activator.CreateInstance(typeof(TSource));
var myResult = source.SingleOrDefault(predicate);
return myResult == null ? myNullObject : myResult;
}

By: LINQ Master

LINQ Master — Wed, 20 Aug 2008 14:03:29 +0000

Great example. It sucks that we have to write our own overloads for the Default extensions. Maybe MS will fix this in the next version of LINQ.

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