{Programming} & Life

Are you getting this?

System.InvalidOperationException:
The null value cannot be assigned to a member with type System.Int64 which is a non-nullable value type.

On something like this?

var totalSize = query.Sum(x => x.Size);

This occurs because your LINQ property (in my case “Size”) is not nullable, and needs to be nullable because your Sum() operation could potentially iterate over a list which is empty yielding your LINQ property value to be null.
Of course you can’t Sum() null as we know or the universe would explode, so try this instead:

var totalSize = query.Sum(x => (long?) x.Size);

This may very well just be a LINQ to SQL thing, but I am not sure. Maybe somebody else out there in the wide world web can enlighten me!

Best of luck!