Question

请告诉我，我明白当你调用getOrders（）时，必须返回完整的Set？

订单表中的FK。

或者您只需要使用HQL（JPQL）来获取Orders对象？

我变空了。当我调用getter时设置orderSet = bid.getOrders（）;在调试中我不显示任何动作。

@Entity
@Table(name = "bid") 
public class Bid {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@OneToMany(mappedBy = "bid_id",cascade = CascadeType.ALL,fetch = FetchType.EAGER)
private Set<Order> orders = new HashSet<>();
@Column(name = "title")
private String title;
@Column(name = "description")
private String description;


public Set<Order> getOrders() {
    return orders;
}

public void setOrders(Set<Order> orders) {
    this.orders = orders;
}

@Entity
@Table(name = "orders")
public class Order {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
@Column(name = "title")
private String title;

@ManyToOne(optional = true,fetch = FetchType.EAGER,cascade = 
CascadeType.ALL)
@JoinColumn(name = "bid")
private Bid bid_id;

@Repository
@Transactional
public class BidDao {

@PersistenceContext
private EntityManager entityManager;

public void create(Bid bid){
    entityManager.persist(bid);
}

}

Answer 1

试试这个

从一方到多方

@OneToMany (targetEntity = Order.class, cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)

@JoinColumn (name = "order_id", referencedColumnName = "id")

从多方到一方

@ManyToOne(targetEntity = Bid.class, optional = true,fetch = FetchType.EAGER,cascade =
        CascadeType.ALL)

@JoinColumn(name = "order_id", referencedColumnName = "id")

Hibernate @OneToMany为空集

1 个答案: