JPA OneToMany not deleting child

Question

I have a problem with a simple  OneToMany mapping between a parent and a child entity  All works well  only that child records are not deleted when I remove them from the collection   The parent    Entity public class Parent        Id      Column name    ID       private Long id        OneToMany cascade    CascadeType ALL   mappedBy    parent       private Set lt Child gt  childs   new HashSet lt Child gt               The child    Entity public class Child        Id      Column name    ID       private Long id        ManyToOne cascade   CascadeType ALL       JoinColumn name  PARENTID   nullable   false      private Parent parent             If I now delete and child from the childs Set  it does not get deleted from the database  I tried nullifying the child parent reference  but that did not work either   The entities are used in a web application  the delete happens as part of an Ajax request  I don t have a list of deleted childs when the save button is pressed  so I can t delete them implicitly

User · Answer

As explained  it is not possible to do what I want with JPA  so I employed the hibernate cascade annotation  with this  the relevant code in the Parent class now looks like this    OneToMany cascade    CascadeType PERSIST  CascadeType MERGE  CascadeType REFRESH   mappedBy    parent    Cascade  org hibernate annotations CascadeType SAVE UPDATE              org hibernate annotations CascadeType DELETE              org hibernate annotations CascadeType MERGE              org hibernate annotations CascadeType PERSIST              org hibernate annotations CascadeType DELETE ORPHAN   private Set lt Child gt  childs   new HashSet lt Child gt       I could not simple use  ALL  as this would have deleted the parent as well

User · Answer

JPA s behaviour is correct  meaning as per the specification   objects aren t deleted simply because you ve removed them from a OneToMany collection  There are vendor-specific extensions that do that but native JPA doesn t cater for it   In part this is because JPA doesn t actually know if it should delete something removed from the collection  In object modeling terms  this is the difference between composition and  aggregation    In composition  the child entity has no existence without the parent  A classic example is between House and Room  Delete the House and the Rooms go too   Aggregation is a looser kind of association and is typified by Course and Student  Delete the Course and the Student still exists  probably in other Courses    So you need to either use vendor-specific extensions to force this behaviour  if available  or explicitly delete the child AND remove it from the parent s collection   I m aware of    Hibernate  cascade delete orphan  See 10 11  Transitive persistence  and EclipseLink  calls this  private ownership   See How to Use the  PrivateOwned Annotation

User · Answer

In addition to cletus  answer  JPA 2 0  final since december 2010  introduces an orphanRemoval attribute on  OneToMany annotations  For more details see this blog entry   Note that since the spec is relatively new  not all JPA 1 provider have a final JPA 2 implementation  For example  the Hibernate 3 5 0-Beta-2 release does not yet support this attribute

User · Answer

Entity  class Employee         OneToOne orphanRemoval true       private Address address      See here

User · Answer

You can try this    OneToOne cascade   CascadeType REFRESH     or    OneToMany cascade   CascadeType REFRESH

User · Answer

Here cascade  in the context of remove  means that the children are removed if you remove the parent  Not the association  If you are using Hibernate as your JPA provider  you can do it using hibernate specific cascade

User · Answer

You can try this    OneToOne orphanRemoval true  or  OneToMany orphanRemoval true

[java] JPA OneToMany not deleting child

Examples related to java

Examples related to jpa

Examples related to jpa-1.0