Question

我有几个实体

@Entity
@Table(name = "A")
public class A {

    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "alIdSeq")
    @SequenceGenerator(name = "aIdSeq", sequenceName = "a_id_seq", allocationSize = 1)
    private Long id;

    @JoinColumn(name = "a_id", referencedColumnName = "id")
    @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.PERSIST)
    private List<B> b = new ArrayList<>();

}

@Entity
@Table(name = "B")
public class B {

    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "blIdSeq")
    @SequenceGenerator(name = "aIdSeq", sequenceName = "b_id_seq", allocationSize = 1)
    private Long id;

}

示例：当我从回购中获取对象A并将新对象B添加到列表中时，存储库不会保存新对象B。

A a = aRepository.findById(someId);
B b = new B();
a.getB().add(B);

注意： Sql表不包含新的B。

Answer 1

您应该将合并添加到层叠，仅在持久化时设置

只需添加CascadeType.MERGE

@JoinColumn(name = "a_id", referencedColumnName = "id")
@OneToMany(fetch = FetchType.LAZY, cascade = {CascadeType.MERGE, CascadeType.PERSIST})
private List<B> b = new ArrayList<>();

Answer 2

您的对象a已经创建并且无法持久运行的主要问题并未发生。如果您尝试使用某些A元素创建（持久）新实体（B），则新B将包含在sql表中。

Spring Data不保存相关实体

2 个答案: