EF 6, Fluent Api mapping in inheritance classes

Question

I am training in class mapping for the Entity Framework using the Fluent API and I have some questions.

The first is as follows: Map a Foreign key with attributes would be like this:

public int EmpresaId {get; set;}
[ForeignKey("EmpresaId")]
public Empresa Empresa {get; set;}

With Fluent API it would be like this:

HasRequired(p => p.Empresa).WithMany().HasForeignKey(p => p.EmpresaId);

Is that correct? What I don’t understand is this WithMany() since it is a simple foreign key connection and is not a ICollection<>, for example. So why WithMany()?

The other question would be, how would the mapping with the Fluent API of these classes, since two inherit from the first?

public class Pessoa
{
    public int Id {get; set;}
    public string Nome {get; set;}
}

public class PessoaFisica : Pessoa
{
    public string CPF {get; set;}
}

public class PessoaJuridica : Pessoa
{
    public string CNPJ {get; set;}
}

Answer 1

Withmany

Is used WithMany() to specify a Many relationship. What’s really weird is the fact that you’re using WithMany() unencumbered. WithMany() serves for you to specify the inverse relation.

For example, if that chunk of code refers to a person, the correct mapping would be like this:

HasRequired(p => p.Empresa)
    .WithMany(e => e.Pessoas)
    .HasForeignKey(p => p.EmpresaId);

Classe Pessoa

One Pessoa in theory can only be Physical or Legal, right? The correct thing would be to do:

public abstract class Pessoa
{
    public int Id {get; set;}
    public string Nome {get; set;}
}

public class PessoaFisica : Pessoa
{
    public string CPF {get; set;}
}

public class PessoaJuridica : Pessoa
{
    public string CNPJ {get; set;}
}

In the Fluent API:

modelBuilder.Entity<PessoaFisica>()
    .HasKey(pf => pf.Id);
modelBuilder.Entity<PessoaFisica>()
    .Property(pf => pf.Nome)
    .HasMaxLength(70)
    .IsRequired();
modelBuilder.Entity<PessoaJuridica>()
    .HasKey(pj => pj.Id);
modelBuilder.Entity<PessoaJuridica>()
    .Property(pj => pj.Nome)
    .HasMaxLength(70)
    .IsRequired();

Answer 2

James, probably your class must be something like this:

public Pessoa {
    public int Id { get; set; }
    public int EmpresaId {get; set;}
    [ForeignKey("EmpresaId")]
    public Empresa Empresa {get; set;}
}

Hence your Company class should be something around

public Empresa {
    public int Id { get; set; }
    //... 
    public ICollection<Pessoa> Pessoas {get; set;}
}

Am I right, sir? If it is, your Fluent relationship should represent as follows:

modelBuilder.Entity<Pessoa>()
            .HasRequired(p => p.Empresa)
            .WithMany(e => e.Pessoas)
            .HasForeignKey(p => p.EmpresaId);

What happens is this: The person Entity<Pessoa> has a mandatory field (required) HasRequired(p => p.Empresa) which is part of a company list WithMany(e => e.Pessoas);

That is, that person needs to have a company and that person will be linked to the people that exist in that company (ICollection).