LINQ, Unable to create a constant value of type XXX. Only primitive types or enumeration types are supported in this context

Question

In my application I have Lecturers and they have list of Courses they can teach and when I\'m deleting a course I want to remove connection to lecturers. Here\'s the code:

Answer 1

The Courses collection of below line should be null or empty.

 var toRemove = db.Lecturers
                        .Where(l => l.Courses.Contains(courseFromDb)).ToList();