deleting parent exception with jpa - jpa

Question

With netbeans 8.1 I have generated entity and jpa controller.
I have a parent entity and a child with a one to one relation.
The child entity has primary key equals to foreign key to the parent:
#Entity
#Table(name = "parent")
#XmlRootElement
public class Parent implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Basic(optional = false)
#Column(name = "id")
private Integer id;
#OneToOne(cascade = CascadeType.ALL, mappedBy = "parent")
private Child child;
public Parent() {
}
etc....
}
#Entity
#Table(name = "child")
#XmlRootElement
public class Child implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Basic(optional = false)
#Column(name = "parent_id")
private Integer parentId;
#JoinColumn(name = "parent_id", referencedColumnName = "id", insertable = false, updatable = false)
#OneToOne(optional = false)
private Parent parent;
public Child() {
}
etc....
}
When I try to delete the parent I get:
IllegalOrphanException: This Parent (model.Parent[ id=1 ]) cannot be destroyed since the Child model.Child[ parentId=1 ] in its child field has a non-nullable parent field.
To avoid this I should delete the child first, but due to cascade.ALL it should be already done automatically.

Answer 1

Coding Child class as follows works
#Entity
#Table(name = "child")
#XmlRootElement
public class Child implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#JoinColumn(name = "parent_id", referencedColumnName = "id")
#OneToOne(optional = false)
private Parent parent;
...
}
Tables look like
create table child (parent_id integer not null,..., primary key (parent_id))
create table parent (id integer not null, ..., primary key (id))
alter table child add constraint ... foreign key (parent_id) references parent
The removal of a parent (em.remove(parent)) leads to
delete from child where parent_id=?
delete from parent where id=?