Bidirectional relationships and JPA

Question

Hi, all!
Consider the following class containing bidirectional relationship:
@Entity
public class Node {
private Node parent;
private Collection<Node> childNodes = new HashSet<Node>();
@ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.REFRESH, CascadeType.MERGE})
public Node getParent() {
return parent;
public void setParent(final Node parent) {
this.parent = parent;
@OneToMany(fetch = FetchType.LAZY, mappedBy = "parent", cascade = {CascadeType.ALL})
public Collection<Node> getChildNodes() {
return childNodes;
public void setChildNodes(final Collection<Node> childNodes) {
this.childNodes = childNodes;
How should this bidirectional relationship be maintained?
Should I maintain synchronization between childNodes and parent programmatically like this:
public void setParent(final Node parent) {
if ( this.parent != parent ) {
this.parent = parent;
parent.addChild(this);
public void addChild(final Node child) {
if ( !childNodes.contains(child) ) {
childNodes.add(child);
child.setParent(this);
or can JPA provider (toplink essentials in J2SE environment) do it for me some way (may be some kind of weaving?).
What is the best practice for this?
Any help highly appreciated, thanks in advance!

Answer 1

In JPA you are responsible for maintaining bi-directional relationships in your own code, it is not part of the specification.