[java] JPA OneToMany not deleting child

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<Child> childs = new HashSet<Child>();

 ...
}

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.

You can try this:

@OneToOne(orphanRemoval=true) or @OneToMany(orphanRemoval=true).

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.

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.

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<Child> childs = new HashSet<Child>();

I could not simple use 'ALL' as this would have deleted the parent as well.

@Entity 
class Employee {
     @OneToOne(orphanRemoval=true)
     private Address address;
}

See here.

You can try this:

@OneToOne(cascade = CascadeType.REFRESH) 

or

@OneToMany(cascade = CascadeType.REFRESH)