title: PreUpdate cascade entity persist symfony 2.3
body: <p>I have a bit of problems with PreUpdate HasLifecycleCallbacks.</p>
  
  <p>I have an entity, let say "A" with have a OneToOne relation with the entity "B". 
  So I have:</p>
  
  <pre><code>/**
   * @ORM\Entity()
   * @ORM\HasLifecycleCallbacks
   */
   class A
  {
      /**
       * @ORM\OneToOne(targetEntity="B", inversedBy="attrA", cascade={"persist", "remove"})
       * @ORM\JoinColumn(name="fieldB", referencedColumnName="id")
       */
      private $attrB;
  
      public function __construct()
      {
          $this-&gt;attrB = new B();
      }
  
      /**
       * @ORM\PrePersist
       * @ORM\PreUpdate
       */
      public function updateSomthing(){
          //$gestor = fopen("/pruebitas.txt", "r");
          $this-&gt;attrB-&gt;setDate($this-&gt;getDate());
     }
  }
  </code></pre>
  
  <p>And class B is: </p>
  
  <pre><code>class B
  {
      /**
       * @ORM\OneToOne(targetEntity="A", mappedBy="attrB")
       */
      private $attrA;
  }
  </code></pre>
  
  <p>When I create a new entity A, everything works fine, the problem is when I update the entity A, the PreUpdate function is fire, (because it creates the file in the commented line), but the entity B does not persist in the database, even if the field in B should be updated.</p>
  
  <p>Any idea to cascade the persist on the PreUpdate??</p>
  
  <p>Thanks!!</p>