Problems with creating not null fields with Fluentnhibernate

Question

I have a problem creating the fields using Fluentnhibernate and Postgres. User class:

public class Usuario {
    public virtual int idUsuario { get; set; }
    public virtual string nome { get; set; }
    [NotNullNotEmpty]
    public virtual string login { get; set; }
    [NotNullNotEmpty]
    public virtual bool ativo { get; set; }
    [NotNullNotEmpty]
    public virtual string senha { get; set; }
}

User:

public UsuarioMap() {
    Table("usuario");
    Id(x => x.idUsuario).GeneratedBy.Identity().Column("id_usuario");
    Map(x => x.nome).Column("nome").Length(50);
    Map(x => x.login).Column("login").Not.Nullable().Length(30);
    Map(x => x.ativo).Column("ativo").Not.Nullable();
    Map(x => x.senha).Column("senha").Not.Nullable().Length(50);
}

If the table does not exist, it normally creates all fields, with correct size and validation not null:

CREATE TABLE public.usuario
(
    id_usuario integer NOT NULL DEFAULT nextval('usuario_id_usuario_seq'::regclass),
    nome character varying(50),
    login character varying(30) NOT NULL,
    ativo boolean NOT NULL,
    senha character varying(50) NOT NULL, 
    CONSTRAINT usuario_pkey PRIMARY KEY (id_usuario)
)

But if the table exists and I add a field in the map class, it just creates the field without the validations:

**Class Usuario**
[NotNullNotEmpty]
public virtual string teste { get; set; }

.

**Class UsuarioMap**
Map(x => x.teste).Column("teste").Length(60).Not.Nullable();

.

CREATE TABLE public.usuario
(
    id_usuario integer NOT NULL DEFAULT nextval('usuario_id_usuario_seq'::regclass),
    nome character varying(50),
    login character varying(30) NOT NULL,
    ativo boolean NOT NULL,
    senha character varying(50) NOT NULL,
    teste character varying(60),
    CONSTRAINT usuario_pkey PRIMARY KEY (id_usuario)
)

If anyone has been through this and can help me, I appreciate it because I am already two days researching and I could not solve.

Answer 1

Missing set the default value for this field and pass a value, because when creating a new field in an existing table if no value is passed it has to be null, by default. Soon this will put the appropriate rules and validations for this field.

Map(x => x.teste).Column("teste").Default("teste").Length(60).Not.Nullable();

Referent: Soen - Specifiying Default Value for Datetime Property in Fluennhibernate Mapping class