is it possible to have a conditional field in an anonymous type

i have some code that looks like this and creates a list from an existing collection

 var items = items.ConvertAll(r => new
            {
                description = FormatDescription(r),
                start = r.Milestone.HasValue ? r.Milestone.Value.ToString("yyyy-MM-ddTHH:mm:ssZ") : DateTime.Today.ToString("yyyy-MM-ddTHH:mm:ssZ"),
                classname = "significance" + r.SignificanceLevel,

As you can see, right now if i dont have a start date (r.Milestone) then i put in today's date. What i really want to do if say:

1. if i have a r.Milestone.Hasvalue show that date, if i dont have a value DONT HAVE THE START DATE field in the anonymous type at all.

Is it possible to have this conditional logic where开发者_如何学运维 you can remove the field all together inside this type of code?

No, you can't, mostly since it would make the anonymous class different in different executions and the class couldn't be type checked.

I'd recommend setting your Start date to null instead of a default, and checking for that later in your code.