Saving bidirectional ManyToMany

Question

I have two entity classes annotated in the following way

@Entity
class A {
   @ManyToMany(mappedBy=\"A\", cascade=CascadeType.ALL)
   private List b         


        

Answer 1

As the relationship is bi-directional so as the application updates one side of the relationship, the other side should also get updated, and be in synch. In JPA, as in Java in general it is the responsibility of the application, or the object model to maintain relationships. If your application adds to one side of a relationship, then it must add to the other side.

This can be resolved through add or set methods in the object model that handle both sides of the relationships, so the application code does not need to worry about it. There are two ways to go about this, you can either only add the relationship maintenance code to one side of the relationship, and only use the setter from one side (such as making the other side protected), or add it to both sides and ensure you avoid a infinite loop.

Source: OneToMany#Getters_and_Setters