java - 如何删除 spring-data-jpa 中多边的项目？

Question

Department和Employee之间是双向的一对多关系。

@Setter
@Getter
@Entity
@Table(name = "t_department")
public class Department {
    @Id
    private String id;

    private String name;

    @OneToMany(mappedBy = "department",fetch = FetchType.EAGER,cascade = CascadeType.ALL)
    private List<Employee> employees;
}


@Setter
@Getter
@Entity
@Table(name = "t_employee")
public class Employee {
    @Id
    private String id;

    private String name;

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "dept_id")
    private Department department;
}

@Repository
public interface EmployeeRepository extends JpaRepository<Employee, String> {

}

在数据库中，我有那些记录。

t_department:
+----+------------+
| id | name       |
+----+------------+
| 2  | accounting |
| 3  | logistics  |
+----+------------+

t_employee:
+----+------+---------+
| id | name | dept_id |
+----+------+---------+
| 3  | Tom  | 2       |
| 4  | Tina | 3       |
+----+------+---------+

当我试图删除一个 Employee(id="3") 时，

    @Test
    @Transactional
    public void should_delete_employee_success_when_delete_employee_given_a_exist_employee_id_in_DB() {
        employeeRepository.delete("3");
    }

但在控制台中，它只打印了 2 条 select 语句而没有删除:

Hibernate: select employee0_.id as id1_2_0_, employee0_.dept_id as dept_id3_2_0_, employee0_.name as name2_2_0_, department1_.id as id1_1_1_, department1_.name as name2_1_1_ from t_employee employee0_ left outer join t_department department1_ on employee0_.dept_id=department1_.id where employee0_.id=?
Hibernate: select employees0_.dept_id as dept_id3_2_0_, employees0_.id as id1_2_0_, employees0_.id as id1_2_1_, employees0_.dept_id as dept_id3_2_1_, employees0_.name as name2_2_1_ from t_employee employees0_ where employees0_.dept_id=?

然后我去看了数据库，什么都没做。

spring-data-jpa 是如何工作的？我困惑了好几天。

提前感谢您的回答。

Answer 1

CrudRepository有方法 delete(<entity>)和 deleteById() .您应该使用 deleteById 而不是实体。