java - Spring Boot Hibernate @OneToMany 集合总是空的

Question

我尝试在 spring boot 中通过存储库加载一些数据。主要实体完全没问题并且包含数据。 @OneToMany 关系集合除外。 从调试输出中可以看到正确的查询，它肯定会返回数据。

问题:

• 即使执行生成的 SQL 并返回结果，bookings 列表也为空。
• stackoverflow 上没有线程可以解决我的问题。

我是这样尝试的:

Optional<Ad> pi = adRepository.findById(adID);
if (!pi.isPresent()) {
    return null;
}
Ad ad = pi.get();

List<Booking> bookings = ad.getItem().getBookings();

// bookings is null. why is it not populated?
// i've also tried use FetchType.EAGER. Didn't helped

广告

@Entity
@Table(schema = "xxx", name = "AD")
public class Ad {
    @Id
    @Column(name = "adID")
    private Long id;

    @OneToOne(optional=true, mappedBy="ad", fetch=FetchType.LAZY, cascade=CascadeType.ALL)
    private Item item;
}

项目

@Entity
@Table(schema="xxx", name="ITEM")
public class Item {
    @Id
    @OneToOne(optional=true, fetch=FetchType.LAZY)
    @JoinColumn(name="adID", unique=true, nullable=false, updatable=false)
    private Ad ad;

    @OneToMany(mappedBy = "item")
    private List<Booking> bookings;
}

预订

@Entity
@Table(schema = "xxx", name = "BOOKING")
public class Booking {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "bookID")
    private Long id;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "adID", nullable = false, referencedColumnName = "adID")
    private Item item;
}

Hibernate 生成的查询

select
bookings0_.adID as adID8_34_0_,
bookings0_.bookID as bookID1_34_0_,
bookings0_.bookID as bookID1_34_1_
from xxx.BOOKING bookings0_
where bookings0_.prditmID=1337

有什么我遗漏的吗？

问候

Answer 1

问题是 Item 类和 @Id 声明。 更改为并且有效。

@Entity
@Table(schema="xxx", name="ITEM")
public class Item {
    @Id
    @Column(name = "adID")
    private Long id;

    @OneToOne(optional=true, fetch=FetchType.LAZY)
    @JoinColumn(name="adID", unique=true, nullable=false, updatable=false)
    private Ad ad;

    @OneToMany(mappedBy = "item")
    private List<Booking> bookings;
}