Spring Data JPA-删除子实体而不是在更新时设置为null？

Question

users
----
id (PK)
name

orders
------
id (PK)
userid (PK)
name

在使用JPA更新用户时，如果我尝试使用

User user = userRepository.getOne(id);
user.getOrders().clear();
userRepository.save(user);

JPA首先尝试将关联订单上的userid设置为null，然后删除该行。这将失败，因为userid是不可为空的，并且是主键的一部分。有没有一种方法可以告诉JPA它只需要删除Order行，而不首先将userid列设置为null？

映射：我有的映射是这样的：

@Entity
@Table(name = "users")
public class User implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name="id")
    public Long id;

    @Column(name="name")
    private String name;

    @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
    @JoinColumn(name="userid", referencedColumnName = "id", insertable = true, updatable = true)
    @Fetch(FetchMode.JOIN)
    private Set<Order> orders;

}

@Entity
@Table(name = "orders")
@IdClass(Order.OrderPk.class)
public class Order implements Serializable {

    @Id
    @Column(name="id")
    private Long id;

    @Id
    @Column(name="userid")
    private Long userId;

    @Column(name="name")
    private String name;

    public static class OrderPk implements Serializable  {

        private Long id;

        private Long userId;
    }
}

@Entity
@Table(name = "users")
public class User implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name="id", nullable = false)
    public Long id;

    @Column(name="name")
    private String name;

    @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER, mappedBy = "orderPk.user")
    @Fetch(FetchMode.JOIN)
    private Set<Order> orders;
}

@Entity
@Table(name = "orders")
public class Order implements Serializable {

    @EmbeddedId
    private OrderPk orderPk;

    @Column(name="name")
    private String name;

    @Embeddable
    public static class OrderPk implements Serializable {

        @GeneratedValue
        @Column(name="id", insertable = false, updatable = false, nullable = false)
        private Long id;

        @ManyToOne(fetch = FetchType.LAZY)
        @JoinColumn(name="userid", referencedColumnName = "id", insertable = false, updatable = false, nullable = false)
        private User user;
    }
}

Answer 1

您可以使用标识符保留联接，并确保delete不会尝试使用集合上的可更新和可插入注释将null写入集合FK。

@Entity
@Table(name = "users")
public class User implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name="id", nullable = false)
    public Long id;

    @Column(name="name")
    private String name;

    @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, fetch =     FetchType.EAGER)
    @JoinColumn(name = "userId", updatable = false, insertable = false)
    private Set<Order> orders;
}

@Entity
@Table(name = "orders")
public class Order implements Serializable {

    @Id
    @Column(name="id")
    private Long id;

    @Column(name="userid")
    private Long userId;

    @Column(name="name")
    private String name;
}

这个

@joincolumn（name=“userid”,updatable=false,insertable=false）