Save only if not null

Question

How do I map with Hibernate @OneToOne and save only if the information has data in the related table?

Example:

public class ObservacaoPessoa {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public Integer id;

    public Integer PessoaId;
    public String TextoObservacao;

}

public class Pessoas {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public Integer id;

    public String Nome;

    public ObservacaoPessoa Obs;

}

I want to make Pessoas.Save but only record the Obs if any value has been reported.

Answer 1

I think what you want is the optional = true in the @OneToOne.

In addition, the inverse relationship (because it is bidirectional) can be done with the mappedBy:

public class ObservacaoPessoa {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    @OneToOne(mappedBy = "obs")
    private Pessoa pessoa;

    private String textoObservacao;

}

public class Pessoas {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    private String nome;

    @OneToOne(optional = true, cascade = CascadeType.ALL)
    private ObservacaoPessoa obs;

}

Other things I notice is that the fields should be private. Do not use public fields, this is a bad programming practice.

To enter an entity, you would do something more or less like this:

EntityManager em = ...;
Pessoa p = ...;
ObservacaoPessoa obs = ...;
if (obs != null) {
    p.setObs(obs);
    obs.setPessoa(p);
}
em.persist(p);

Finally, to make bi-directional mapping work, you must manually set both sides of the relation as you would with any other two Java objects that need to be referenced cyclically.