Question

I have a situation were I have a class Called Order with a generated OrderID :

    @Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq_gen")
@SequenceGenerator(name = "seq_gen", sequenceName = "OID_SEQ1")
@Column(name = "ORDER_ID",nullable = false)
public long getOrderId()
{
    return this.OrderId;
}

it also has a one-to-many mapping with a class/ table called items:

    @OneToMany(fetch = FetchType.LAZY,mappedBy = "orders",targetEntity = Items.class)
public Set<Items> getItems()
{
    return this.items;
}

within the items class is an embedded/composite id:

    @EmbeddedId
@AttributeOverrides({@AttributeOverride(name = "OrderId",column = @Column(name = "ORDER_ID",nullable = false)),
        @AttributeOverride(name = "role",column = @Column(name = "ROLE",nullable = false,length = 10))})
public ItemId getId()
{
    return this.id;
}

My problem is part of this id is the primary key of the parent Order.class. In other words the sequence value. This means I cannot set this value anywhere and when I call:

entitymanager.persist(order);

The parent Order object writes to the db BUT none of the items within the Set are persisted. There is only one insert statement and all the references to orderId in the Items objects are null????

How can I populate these ID’s with the generated Seq ID?

Many thanks for any help with this!

Answer 1

Eventually figured this out with the help of another post:
onetomany-and-composite-primary-keys
The answer was in fact quite simple. We need to use the Casade annotation to casade the Id down to the child object. so the one to many mapping above becomes:

@OneToMany(cascade = CascadeType.ALL,fetch = FetchType.LAZY,mappedBy = "orders",targetEntity = Items.class) public Set<Items> getItems() {     return this.items; } 

When implementing this review the different cascade types.

Good luck