Why null is returned?

问题:

I can not understand what I'm doing wrong

Not null:

var workPanels = (IEnumerable)context.WorkPanels;

Null:

var nowWorkPanels = from wp in context.WorkPanels select wp;

Why?

回答1:

This shouldn't be the case. from wp in context.WorkPanels select wp; is equivalent to context.WorkPanels.Select(wp => wp);. The MS implementations of Select (Enumerable.Select / Queryable.Select) never return null.
There must be something else wrong somewhere else.