A @Embeddable that behaves like a @OneToOne (HIBERNATE)

Question

Hi,

I have a class named Parent as follows

@Entity
public class Parent {

    @Id
    @GeneratedValue
    private Integer id;

    @Embedded
    private Message message;

}

DBA (minimal OOP knowledge) has designed both Parent and Message properties in PARENT table. Message class behaves like a @OneToOne mapping because, at some cases, according to business requirement, it has:

• Independent lifespan of the owning entity instance (Parent class)

But @Embeddable class, by default, share the same table of the owning entity (Another approach could be use a @SecondaryTable). So, i have a @Embeddable class - share the the same table of the owning entity - that behaves like a @OneToOne - according to business requirement.

Sometimes i want to update a Parent object but I DO NOT WANT to update a Message @Embedded property due business requirement (see above). When i retrieve my updateable Parent object, its message property will be null. Then Message properties will be null in database because its lifespan is bound to the lifespan of the owning entity instance (Parent). So how can i avoid @Embedded Message property to be updatable ?

Regards,

Answer 1

Can you provide more details?
Normally Hibernate will NOT try to update something that did not change, e.g. if your Message wasn't touched by UI code columns it's mapped to would not be part of the UPDATE statement. If they are, that means Message was changed by your UI, and that's where you should be looking for a cause of this.

Answer 2

Hi,

as said:

DBA (minimal OOP knowledge) has designed both Parent and Message properties in PARENT table. Message class behaves like a @OneToOne mapping because, at some cases, according to business requirement, it has:

• Independent lifespan of the owning entity instance (Parent class)

But @Embeddable component, by default, share the same table of the owning entity (Another approach could be use a @SecondaryTable). So, i have a @Embeddable component - share the the same table of the owning entity - that behaves like a @OneToOne - according to business requirement.

So in order to support it, a workaround is introduced as follows

I have created a UpdateableParent in order to use it in UI interface. UpdateableParent only contains necessary updatable fields without its @Embedded Message property.

public class UpdateableParent {

    // Parent class properties whithout its @Embedded Message property

    // getters and setters

}

So when i retrieve my UpdateableParent object, i use Automatic dirty checking feature according to:

public class ParentRepositoryImpl implements ParentRepositoryImpl {

    // dependency injection
    private SessionFactory sessionFactory;

    // Spring transaction boundary
    public void updateParent(UpdateableParent updateableParent) {

        // load method loads a proxy Parent object
        Parent parent = (Parent) sessionFactory.openSession().load(Parent.class, updateableParent.getId());

        // Them i copy updatable parent properties to proxied parent object, nothing else
        // Automatic dirty checking only updates modified fields in proxied Parent object
        BeanUtils.copyProperties(updateableParent, parent);

    }
}

This way, only UpdateableParent properties will be updateable in database.

Regards,

Arthur Ronald F D Garcia (Java programmer)

Natal/RN (Brazil)