Unable to create a constant value of type 'System.Object'. Only primitive types ('such as Int32, String, and Guid') are supported in this context

Question

I'm using MVC and Entity Framework. I've created a class in my model folder with this code below. I keep getting the error message above with both queries below. I know there is a known issue on referencing non-scalar variables, but I'm not sure how to implement a workaround:

http://msdn.microsoft.com/en-us/library/bb896317.aspx#Y1442

private MovieLibraryDBEntities movieLibraryDBEntitiesContext;

public int getNumberOfEntriesReserved()
{
    return (from m in movieLibraryDBEntitiesContext.Movies
            where m.CheckedOut.Equals(1)
            select m).Count();

    //return movieLibraryDBEntitiesContext.Movies
    //  .Where(e => e.CheckedOut.Equals(1))
    //  .Select (e => e.Title).Count();
}

Answer 1

You cannot use m.CheckedOut.Equals(1) in linq-to-entities query. Use m.CheckedOut == 1 but CheckedOut must be integer.

Answer 2

This is an older question. I had the same problem when trying to filter a nullable column using the IQueryable interface. I solved the problem by first checking to see if the object had a value and then checking the value.

widgets = widgets.Where(x => x.ID.HasValue.Equals(true) &&  x.ID.Value.Equals(widgetID));

Answer 3

same issue using Any() i had to change my where clause to search on primitive types, for me int

so this

where order.User == user

becomes this

where order.User.UserId == user.UserId

There is a blog post explaining the quirk.