休眠：主键由外键构成

Question

So I have "OrderItem" class. Its primary key its suppose to be made of "productID" and "orderID" (both FK reference from another entities). How can I set that up using annotations?

Thanks in advance!!!!

Table : ordersItems
Attributes : productID (PK-PK) ------------------> Product
orderID (PK-PK) ------------------> Order

Given these entities:

@Entity
@Table(name="products")
public class Product {

    @Id
    @Column(name="productID")
    private Integer id;
    private String description;
}


@Entity
@Table(name="orders")
public class Order{

    @Id
    private int orderID;

    @OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER)
    @JoinColumn(name="orderID")
    private List<OrderItem> items;
}

@Entity
@Table(name="ordersItems")
public class OrderItem{

    @ManyToOne( cascade = {CascadeType.PERSIST, CascadeType.MERGE} )
    @JoinColumn(name="productID")
    private Product product;
    private int quantity;
    private float price;
}

Answer 1

You will have to make an embeddable domain class that has only the fields in your primary key built of foreign keys. The annotation is at the class level, @Embeddable, on the foreign key domain class.

Here is the docs for EmbeddedId

http://docs.oracle.com/javaee/6/api/javax/persistence/EmbeddedId.html