java - Hibernate OneToMany 列表为空

Question

我的实体:

客户.class

@Entity
@Table(name="customer", schema = "pbis", catalog = "feivel")
public class Customer {

    @Id
    @Column(name = "customerid")
    private long id;
    ...
    @OneToMany(mappedBy = "customer", fetch = FetchType.LAZY)
    private Set<Invoice> invoices;

    @OneToMany(mappedBy = "customer", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    private Set<Receipt> receipts;
}

发票.类

@Entity
@Table(name="invoice", schema = "pbis", catalog = "feivel")
public class Invoice {
    @Id
    @Column(name = "invoicenumber")
    private long invoiceNumber;

    @ManyToOne
    @JoinColumn(name = "customerid", insertable = false, updatable = false)
    private Customer customer;
}

收据类

@Entity
@Table(name = "receipts", schema = "pbis", catalog = "feivel")
public class Receipt {
    @EmbeddedId
    private ReceiptId id;

    @ManyToOne
    @JoinColumn(name = "customerid", insertable = false, updatable = false)
    private Customer customer;

一个简单的 Hibernate 查询

SELECT c FROM Customer WHERE c.id = :id

我得到了 c.getInvoices().size(); 的正确大小但是c.getReceipts().size();返回零

当我使用 eclipselink 进行相同的查询时，我得到了收据和发票的正确大小。

EntityManagerFactory emf = Persistence.createEntityManagerFactory("eclipselink");
EntityManager em = emf.createEntityManager();

javax.persistence.Query q = em.createQuery("SELECT c FROM Customer c WHERE c.id = :id");
q.setParameter("id", Long.valueOf(event.getText()));

将 Criteria 与 ResultTransformer 一起使用也可以给我正确的收据大小

Criteria c = session.createCriteria(Customer.class);
c.add(Restrictions.eq("id", Long.valueOf(event.getText())));
c.setFetchMode("receipts", FetchMode.JOIN);
c.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);
for (Object o : c.list()) {
    Customer r = (Customer) o;
    System.out.println(r.getReceipts().size());
}

使用SELECT r FROM Receipt WHERE r.customer.id = :id，我得到了正确的r.getCustomer()，但收据集仍然是空的。

那么..我的映射或者我的想法哪里错了？

谢谢

Answer 1

查看 hibernate sql 日志，我发现收据实体中的附加 @ManyToOne 映射出现了错误。

我将Optional = true添加到映射中，现在我得到了正确的配方集大小。

尽管我认为没有它它应该也能工作，因为 Java 文档说可选默认为 true。