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Editorial Team
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Asked: 2026-05-27T18:51:50+00:00

I am developing a web application using JSF and JPA(Eclipse link). I have two

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I am developing a web application using JSF and JPA(Eclipse link). I have two entities with bidirectional OneToMany relationship. The owner entity is contact and target entity is customer. Single customer can have multiple contacts, like email, phone, etc. When the end user is adding a new customer, he also adds the contacts straight away. There is a need to cancel the saving of a new customer, even after adding contacts to that customer. I tried to add that functionality, but failed in the following way.

Can that senario be achieved directly by persistence?

Contact Entity

....
public class Contact implements Serializable {
    ....   
    @ManyToOne
    Customer customer;
    ....

Customer Entity

....
public class Customer implements Serializable {
    ....
    @OneToMany(mappedBy = "customer")
    private List<Contact> contacts;
    ....

Adding a new contact to Customer (current is an object of Customer class)

Contact contact = new Contact();
contact.setCustomer(current);
....
current.getInstitutionContacts().add(contact);

This works when the current is already a persisted one. If I tried to add a contact to yet to persist one, there is a java.lang.NullPointerException.

I can work around to achieve the functionality, but is there any way we can just collect the contacts to the array and persist them only when (and if only) the customer is persisted? By using cascade persist or lazy fetch, etc?

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1 Answer

  1. Editorial Team

    Sounds like you want Contacts to be Components, not Entities.

    The difference is that an entity has it’s own lifecycle; it lives outside the scope of its association, and deleting the parent does NOT necessarily have to delete the child. Also, if a child is an Entity, other classes can also have relationships with that child.

    Components are completely bound to the parent. They automatically go away if the parent goes away. They cannot be referenced by other associations or by other Entities. It’s like they are simple properties of the parent class.

    The only caveat is that I don’t know if all JPA implementations support having a collection of components.

    See this documentation. Particularly the part that says: "You can also use association annotations in an embeddable object (ie @OneToOne, @ManyToOne, @OneToMany or @ManyToMany). To override the association columns you can use @AssociationOverride."

    If the JPA implementation you are using does, you can use the @Embeddable annotation and @OneToMany

    Edit: — I also found info here http://en.wikibooks.org/wiki/Java_Persistence/Embeddables#Collections.

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