How to do Linq aggregates when there might be an empty set?

Question

I have a Linq collection of Things, where Thing has an Amount (decimal) property.

I\'m trying to do an aggregate on this for a

Answer 1

To get a non-nullable result, you need to cast the amount to a nullable type, and then handle the case of Sum returning null.

decimal total = myThings.Sum(t => (decimal?)t.Amount) ?? 0;

There's another question devoted to the (ir)rationale.