c# - Only primitive types or enumeration types are supported in this context

Question

I've seen lots of questions on this topic, but I haven't been able to sort through any of them that actually solve the issue I'm seeing. I have an activities entity that tracks which employee it is assigned to as well as which employee created the record and updated it. If I remove the `where a.AssignedEmployee == currentUser' line of code, I don't get the run time error below.

Unable to create a constant value of type 'DataModels.Employee'. Only primitive types or enumeration types are supported in this context.

CONTROLLER

var query = from a in db.Activities
            where a.AssignedEmployee == currentUser
            where a.IsComplete == false
            orderby a.DueDate
            select a;
return View(query.ToList());

VIEW

@model IEnumerable<Data.DataModels.Activity>
..........

Answer 1

My guess is that error indicates that EF cannot translate the equality operator for Employee to SQL (regardless of whether you're assuming referential equality or an overridden == operator). Assuming the Employee class has a unique identifier try:

var query = from a in db.Activities
            where a.AssignedEmployeeId == currentUser.Id
            where a.IsComplete == false
            orderby a.DueDate
            select a;
return View(query.ToList());