java - 为什么 JpaRepository 的删除方法实际上并没有从数据库中删除元素？

Question

我有这两门课:

@Entity
public class Dinner {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long dinnerId;

    @Column(unique = true)
    private String date;

    @OneToMany(mappedBy="dinner", orphanRemoval = true, cascade = CascadeType.PERSIST)
    private List<DinnerTable> tables = new ArrayList<>();

@Entity
public class DinnerTable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long dinnerTableId;
    private int places;

    @ManyToOne
    @JoinColumn(name = "dinner_id")
    @JsonIgnore
    private Dinner dinner;

如果我执行此操作，即使它为每个dinnerTable执行deleteById方法，它也不会删除任何内容。

@Override
public void test1(String date) {
    Dinner dinner = dinnerService.getByDate(date);

    for(DinnerTable table: dinner.getTables()){
         dinnerTableRepository.deleteById(table.getDinnerTableId());
    }
}

相反，如果我执行此方法，它会从数据库中正确删除 DiningTable 对象。

@Override
public void test2(String date) {
    Dinner dinner = dinnerService.getByDate(date);

    dinnerTableRepository.deleteById(1);
    dinnerTableRepository.deleteById(2);
    dinnerTableRepository.deleteById(3);
}

这些方法位于该服务类中

@Service
@Transactional
public class DinnerServiceImpl implements DinnerService {...}

DinnerTableRepository 就是这个类:

@Repository
public interface DinnerTableRepository extends JpaRepository<DinnerTable, Long> {
}

编辑

这也不起作用:

List<DinnerTable> tables = dinner.getTables();
for(int i = 1; i < 3; i++){           
    dinnerTableRepository.deleteById(tables.get(i).getDinnerTableId());
}

这工作正常，它实际上从数据库中删除了 DiningTable 对象:

long id = 40;  //id of the first DinnerTable to remove
for(int i = 1; i < 3; i++){
    dinnerTableRepository.deleteById(id + i);
}

编辑2

这有效:

List<Long> ids = new ArrayList<>(Arrays.asList(43L, 44L, 45L));
for(Long id: ids){
    dinnerTableRepository.deleteById(id);
}

编辑3

这样就可以了:

for(int i = 0; i < dinner.getTables().size(); i++){
    dinner.removeTable(dinner.getTables().get(i));
}
dinnerRepository.save(dinner);

Answer 1

您在 @OneToMany 和 @ManyToOne 中遇到问题。

此外，我正在使用 Project Lombok注释

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table

据我了解，Dinner-class 是主要对象，DinnerTable-class 是依赖对象。

在此示例中，我将使用@OneToMany/@ManyToOne双向。

read this about cascade

试试这个代码:

Diner.java:

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table
public class Dinner {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "dinner_generator")
    @SequenceGenerator(name="dinner_generator", sequenceName = "dinner_seq", allocationSize = 1, initialValue = 1)
    private long dinnerId;

    @Column(unique = true)
    private String date;

    @OneToMany(
            mappedBy = "professor",
            cascade = CascadeType.ALL,
            orphanRemoval = true
    )
    private List<DinnerTable> tables = new ArrayList<>();

    /* 
    Use methods below to add or remove tables!!!!!!
    */

    public void addDinnertable(DinnerTable dinnerTable) {
        tables.add(dinnerTable);
        dinnerTable.setDinner(this);
    }

    public void removeDinnertable(DinnerTable dinnerTable) {
        tables.remove(dinnerTable);
        dinnerTable.setDinner(null);
    }

DinnerTable.java:

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table
public class DinnerTable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "dintable_generator")
    @SequenceGenerator(name="dintable_generator", sequenceName = "dintable_seq", allocationSize = 1, initialValue = 1)
    private Long id;

    private long dinnerTableId;

    private int places;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "dinner_id")
    private Dinner dinner;