CODEWITHSUNDEEP
javahibernatespring-bootrelationship
Adrian Adamczyk
Adrian Adamczyk

Reputation: 3080

Hibernate - delegate relations and their management to subclass in order to keep nice and tidy

Right now I have an User entity which contains its specific fields like id, name, password. The user is also an owner of Item entities, which are in Many-to-one and vice-versa relationship:

@Entity
@Table(name="users")
public class User {
    /* Id, name, password etc - strictly User specified */



    private List<Item> ownedItems;
    private List<Bike> ownedConsumables;


    @OneToMany(fetch = FetchType.EAGER, mappedBy = "owner")
    @Fetch(FetchMode.SELECT)
    public List<Item> getOwnedItems() {
        return ownedItems;
    }

    @OneToMany(fetch = FetchType.EAGER, mappedBy = "owner")
    @Fetch(FetchMode.SELECT)
    public List<Consumable> getOwnedConsumables() {
        return ownedConsumables;
    }




    // a lot of methods to manage collections to keep one-to-many consistency 
    // which are not related to strictly to User entity
}

Due to many consistency problems related with such an organisation (bidirectional), I want manage them myself by properly implementing methods like addItem, removeItem etc. These are not directly related to User entity and I think I should move this responsibility to another class. I thought about:

@Table(name="users")
public class User {
    /* Id, name, password etc - strictly User specified */

    private Inventory inventory;
}




public class Inventory {
    private User owner; // if needed - I think it will

    private List<Item> ownedItems;
    private List<Bike> ownedConsumables;


    @OneToMany(fetch = FetchType.EAGER, mappedBy = "owner")
    @Fetch(FetchMode.SELECT)
    public List<Item> getOwnedItems() {
        return ownedItems;
    }

    @OneToMany(fetch = FetchType.EAGER, mappedBy = "owner")
    @Fetch(FetchMode.SELECT)
    public List<Consumable> getOwnedConsumables() {
        return ownedConsumables;
    }

    // a lot of methods to manage collections to keep one-to-many consistency 
}

Is this possible to do with Hibernate? How can I map everything to properly populate these collections?

Another idea is to create a class which will retrieve User object and manage collections, but this one requires ownedItems and ownedConsumables fields to be exposed via getters. Seems a worse one.

Upvotes: 1

Views: 772

Answers (1)

JB Nizet
JB Nizet

Reputation: 692211

You can do that by annotating the class with @Embeddable, and the field inventory with @Embedded.

Upvotes: 1

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