Question

我有两个类，它们的表彼此具有双向关系。员工可以与多个服务类别相关联，反之亦然。连接表在Service Categories类中声明。

当我希望保存Employee对象时，在连接表中没有保存任何内容，但如果我尝试打印与员工相关的服务类别，那么我将获得所有详细信息

if(employee.getServiceCategories()!= null && employee.getServiceCategories().size()>0){
  for(ServiceCategory serviceCategory : employee.getServiceCategories()){
    logger.debug("employee's serviceCategory id : " + serviceCategory.getId());
    logger.debug("employee's ServiceCat Name  : " + serviceCategory.getServiceCatName());
  }
}

Employee.java

@Entity
@Table(name = "employee")
public class Employee extends BaseEntity {
  @Id
  @Column(name = "id")
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  @ManyToMany(mappedBy="employees")
  private List<ServiceCategory> serviceCategories = new ArrayList<>();
}

ServiceCategory.java

@Entity
@Table(name = "servicecategory")
public class ServiceCategory  extends BaseEntity {
  @Id
  @Column(name = "id")
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  @ManyToMany(targetEntity = Employee.class, cascade = { CascadeType.ALL })
  @JoinTable(name = "servicecategory_employee", joinColumns = { @JoinColumn(name = "servicecatid") }, inverseJoinColumns = { @JoinColumn(name = "empid") })
  private List<Employee> employees = new ArrayList<>();
}

感谢您的帮助。

更新

我将Employee.java中的代码更改为

@ManyToMany(mappedBy="employees", cascade = CascadeType.ALL)
private List<ServiceCategory> serviceCategories = new ArrayList<>();

此外，我现在使用以下代码，同时在我的DAO类中保存Employee

public void addEmployee(Employee employee) throws SmrException {
        Session session = this.sessionFactory.getCurrentSession();
        session.merge(employee);
        logger.info("Employee saved successfully, employee Details="
                + employee);
    }

但结果仍然相同。我无法在连接表中保存数据

Answer 1

您正在设置关联的反面（具有#circular { width: 150px; height: 150px; border-radius: 150px; -webkit-border-radius: 150px; -moz-border-radius: 150px; background: url(http://media-cdn.tripadvisor.com/media/photo-s/02/5f/16/e4/la-jolla-cove.jpg) no-repeat; position: absolute; top: 15px; left: 35px; } div.SanDiego { background-color: #ff604c; padding: 15px; opacity: 0.5; position: absolute; top: 220px; left: 35px; font-size: 20px; color: #999; } #maps { background-color: white; height: 300px; width: 220px; border-style: solid; border-color: #B4B4B4; float: left; position: relative; } #menu { right: 52px; bottom: 638px; } body { background-color: #E8E8E8; } nav { background-color: white; height: 75px; width: 1140px; float: left; border-style: solid; border-color: #B4B4B4; margin-left: 30px; } nav ul {} nav ul li { list-style-type: none; width: 150px; float: left; text-align: center; } li a { text-decoration: none; color: #999; line-height: 50px; display: block; } li a:hover { text-decoration: underline; color: #FF604C; }属性的那个）。 JPA仅考虑所有者方（没有 mappedBy属性）。

您需要将员工添加到其所有服务类别，而不仅仅是将服务类别添加到员工。

Spring许多对双向保存数据

1 个答案: