nullable object must have a value

Question

There is paradox in the exception description: Nullable object must have a value (?!)

This is the problem:

I have a DateTimeExtended class, tha

Answer 1

When using LINQ extension methods (e.g. Select, Where), the lambda function might be converted to SQL that might not behave identically to your C# code. For instance, C#'s short-circuit evaluated && and || are converted to SQL's eager AND and OR. This can cause problems when you're checking for null in your lambda.

Example:

MyEnum? type = null;
Entities.Table.Where(a => type == null || 
    a.type == (int)type).ToArray();  // Exception: Nullable object must have a value