Question

I’d like to change the default behavior of .Where method for specific case(s).

All my Business Objects inherit from BaseObject that has property int ID {get; set;}

// Base class
public abstract class BaseObject
{
    public abstract int ID {get; set;}
}

I have 2 classes:

public partial class User : BaseObject
{
    public override int ID {get; set;}
    public string Username { get; set; }
    public int ProfileID { get; set; }

    public virtual Profile Profile { get; set; }
}

public partial class Profile : BaseObject
{
    public override int ID { get; set; }
    public string Name { get; set; }
    public virtual ICollection<User> Users { get; set; }

    public static Profile GetAdminProfile()
    {
        return new Profile(){ID = 3, Name = "Admin profile"};
    }
}

I would like to write

// This throws Unable to create a constant value of type 'Profile'... exception
User admin = Users.Where(user.Profile == Profile.GetAdminProfile()).FirstOrDefault();

instead of

User admin = Users.Where(user.Profile.ID == Profile.GetAdminProfile().ID).FirstOrDefault();

Is there a way to achieve this?

Answer 1

This is a known problem in Entity Framework. You will have follow the second approach.