Question

我在帖子中创建了一个OneToOne关系：https://stackoverflow.com/a/536102/494659

同样，我们有两个实体：Invoice＆amp; InvoiceSequence基本上是它的序列。

@Entity
@Table(name = "invoices", indexes = {...})
@JsonIgnoreProperties(ignoreUnknown = true)
public class Invoice implements Serializable {

    private static final long serialVersionUID = 1L;

    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid2")
    @Id
    private String id;

    @OneToOne(cascade = CascadeType.ALL, mappedBy = "invoice")
    private InvoiceSequence invoiceSequence;

    ...
}

和InvoiceSequence实体：

@Entity
public class InvoiceSequence {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long seqId;

    @OneToOne
    private Invoice invoice;

    @Override
    public String toString() {
        return new ToStringBuilder(this)
                .append("seqId", seqId)
                .toString();
    }
}

但是当我们保存Invoice时，InvoiceSequence保存为null。例如，在我的单元测试中;

Invoice invoice = new Invoice();
    invoice.setFleetId("F0001");
    invoice.setInvoicesStatus(InvoicesStatus.PENDING);
    invoice.setPricingId("1V1");
    invoice.setInvoiceDate(Date.from(toInstant));
    invoice.setTripId("000011111");
    invoice.setServiceId("001111");
    invoice.setUserId("1");
    invoice.setAmount(new BigDecimal("56"));
    invoiceService.save(invoice);

当我调试并查看（在内存中，H2）db时，我看到invoiceSequence为null。

问题非常简单：当我们插入新的Invoice 时，如何确保我们在long值中增加了InvoiceSequence？

但我不能让它发挥作用，任何想法我做错了什么？

由于

Answer 1

这似乎是实现序列的错误方法。你为什么不在Invoice中有另一个字段，例如sequence，并使用以下内容生成它：

Multiple Hibernate sequence generators for one entity with PostgreSQL

此外，如果您确实希望按照建议的方式执行此操作，则需要手动创建InvoiceSequence，然后在保存之前将其设置为Invoice。您还需要将Invoice设置为InvoiceSequence，如下所述：

https://www.callicoder.com/hibernate-spring-boot-jpa-one-to-one-mapping-example/

Spring Boot JPA OneToOne关系：如何在保存时强制插入两个实体？

1 个答案: