title: jpa hibernate one-to-one update
body: <p>I'm working on an apartment management software and I'm having an issue.</p>
  
  <p>There is two entities I have :</p>
  
  <pre><code>@Entity
  public class Tenant extends AbstractEntity { //AbstractEntity contains the id
      @Column(nullable = false)
      private int number;
      @OneToOne
      private Apartment apartment;
  }
  </code></pre>
  
  <p>and</p>
  
  <pre><code>@Entity
  public class Apartment extends AbstractEntity { //AbstractEntity contains the id
      @Column(nullable = false)
      private int number;
      @OneToOne
      private Tenant tenant;
  }
  </code></pre>
  
  <p>But when I do </p>
  
  <pre><code>EntityManager em = emProvider.get();
  em.getTransaction().begin();
  
  em.merge(apartment);
  em.flush();
  
  em.getTransaction().commit();
  </code></pre>
  
  <p>It only save the Tenant into the Apartment but I would like it also update the Apartment into the Tenant.</p>
  
  <p>Do I really need to set the apartment field into the tenant or there is a way to fix it simply?
  Thanks</p>
  
  <p>Cordially,
  Baskwo</p>