Problem modelling relationship in Entity Framework using code first

Question

I\'m trying to learn code first within the Entity Framework and am having trouble modelling a relationship. It\'s a basic HR database which for the sake of this has two enti

Answer 1

That because your model configuration is incomplete - you started your own mapping with Fluent API so you must tell EF that these properties are indeed FKs for relations. For employee use:

modelBuilder.Entity()
            .HasOptional(x => x.Department)
            .WithMany()
            .HasForeignKey(x => x.DepartmentID);

And for department use:

modelBuilder.Entity()
            .HasOptional(x => x.Manager)
            .WithMany()
            .HasForeignKey(x => x.ManagerID);
modelBuilder.Entity()
            .HasOptional(x => x.TeamAdministrator);
            .WithMany()
            .HasForeignKey(x => x.TeamAdministratorID);

Btw. without collection navigation properties on opposite side of relations it will be hard to use model (all WithMany are empty). At least Department should have:

public virtual ICollection Employees { get; set;}

And mapping should be modified to:

modelBuilder.Entity()
            .HasOptional(x => x.Department)
            .WithMany(y => y.Employees)
            .HasForeignKey(x => x.DepartmentID);