I’m trying to use table splitting with EF Core 8 and I’m having some issues with the mappings. Here’s what my types look like:

public class Employee
{

    public int Id{ get; set; }

    public int Version{get; set}

    public string Name{ get; set; }

    // other properties
}

public class EmployeeSummary
{

    public int Id{ get; set; }

    public string Name{ get; set; }

    public Employee Emnployee { get;set;}
}

And here are the mappings:

public sealed class EmployeeTypeConfiguration: IEntityTypeConfiguration<Employee> 
{
    
    public void Configure(EntityTypeBuilder<Employee> builder) 
    {
        builder.ToTable("Employees");
        
        builder.HasKey(f => f.Id);
        builder.Property(f => f.Id).HasColumnName("EmpId");
        
        builder.Property(f => f.Version).IsConcurrencyToken( );

        builder.Property(f => f.Name).HasColumnName("Name");

       // other mappings
   }
}


public sealed class EmployeeSummaryTypeConfiguration: IEntityTypeConfiguration<EmployeeSummary> 
{
    public void Configure(EntityTypeBuilder<EmployeeSummary> builder) 
    {
        builder.ToTable("Employees");
        
        builder.HasKey(f => f.Id);
        builder.Property(f => f.Id).HasColumnName("EmpId");
        
        builder.Property<int>("Version").IsConcurrencyToken( );
        
        builder.Property(e => e.Name).HasColumnName("Name");

        builder.HasOne(f => f.Employee)
               .WithOne( )
               .HasForeignKey<Employee>(f1 => f1.Id);
        builder.Navigation(f => f.Employee).IsRequired( );

    }
}

After adding EmployeeSummary, I’m no longer able to insert a new Employee:

Employee emp = new("123123123");
employee.UpdateWorkPlace(newWorkplace);
// more code
dbContext.Set<Employee>().Add(emp)
await dbContext.SaveChangesAsync();  // throws exception

When I run the previous snippet, I’ll end up with the following error:

System.InvalidOperationException
The value of ‘Employee.Id’ is unknown when attempting to save changes. This is because the property is also part of a foreign key for which the principal entity in the relationship is not known.

What am I doing wrong?

Thanks.