在多对多关系的情况下获取结果

Question

我有三张桌子

1. 员工：存储员工信息

2. role_description：存储我拥有的角色类型，例如管理员、区域经理、国家经理

3. employee_role_details：从员工和角色描述中具有多对多关系以及一些额外的字段。

现在我在从员工表中获取包含 (employee_id, email) 的结果时遇到问题，从employee_role_details 中获取 (role_ownership, role_id) 以及从对应于 role_description 中的角色 ID 的角色描述中获取 (role_name 和角色描述)。

Employee.java

@Entity
@Table(name = "employee", uniqueConstraints= @UniqueConstraint(columnNames={"employee_email"}))
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "employee_id")
    private long employeeId;

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

    @Column(name = "employee_email", unique = true, nullable = false)
    private String employeeEmail;

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

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

    @Column(name = "is_active")
    private Boolean isActive = true;

    @Transient
    private long EmployeeRoleId;

    @Transient
    private String roleName;

    @Transient
    private int totalpage;

    @OneToMany(mappedBy = "employee", cascade = CascadeType.ALL)
    //@JsonIgnore
    @JsonManagedReference(value = "employeeRoleRecord-employee")
    @LazyCollection(LazyCollectionOption.FALSE)
    private List<EmployeeRoleRecord> roleRecords = new ArrayList<>();

    @OneToMany(mappedBy = "assignedTo", cascade = CascadeType.ALL)
    @JsonManagedReference(value = "complaint-treatment-employee")
    @LazyCollection(LazyCollectionOption.FALSE)
    private List<ComplaintsCategory> complaintCategoryAssignedTo = new ArrayList<>();

EmployeeDescription.java

@Entity
@Table(name = "role_description")
public class RoleDescription {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "role_id")
    private long roleId;

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

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

    @Column(name = "status")
    private boolean status;

    @OneToMany(mappedBy = "description", cascade = CascadeType.ALL)
    @JsonManagedReference(value = "employeeRoleRecord-roleDescription")
    @LazyCollection(LazyCollectionOption.FALSE)
    private List<EmployeeRoleRecord> roleRecords = new ArrayList<EmployeeRoleRecord>();

员工角色记录

@Entity
@Table(name = "employee_role_record")
public class EmployeeRoleRecord {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "employee_role_id")
    private long employeeRoleId;

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

    @Column(name = "status")
    private boolean status = true;


    @ManyToOne(cascade=CascadeType.ALL)
    @JsonBackReference(value = "employeeRoleRecord-employee")
    @JoinColumn(name = "employee_id")
    private Employee employee;

    @ManyToOne(cascade=CascadeType.ALL)
    @JsonBackReference(value = "employeeRoleRecord-roleDescription")
    @JoinColumn(name = "role_id")
    private RoleDescription description;

    @Transient
    private long roleId;

dao 内的代码

public Employee getEmployeeByEmail(String email) {
        return (Employee) sessionFactory.getCurrentSession()
                .createCriteria(Employee.class)
                .add(Restrictions.eq("employeeEmail", email)).uniqueResult();
    }

服务：

public Employee getSurveyData(String employeeEmail){

        Employee loggedInEmployee =
                 loginDao.getEmployeeByEmail(employeeEmail);

        Employee  loggedInEmployeeRecord = new Employee();

            loggedInEmployeeRecord.setEmployeeId(loggedInEmployee.getEmployeeId());
            loggedInEmployeeRecord.setEmployeeName(loggedInEmployee.getEmployeeName());

            List<EmployeeRoleRecord> employeeRoleRecords = loggedInEmployee.getRoleRecords();

            List<EmployeeRoleRecord> employeeRoleRecord = new  ArrayList<>();

            for(EmployeeRoleRecord record :  employeeRoleRecords){

                EmployeeRoleRecord employeeRole = new EmployeeRoleRecord();

                employeeRole.setRoleId(record.getDescription().getRoleId());
                employeeRole.setRoleName(record.getDescription().getRoleName());
                employeeRole.setRoleOwnership(record.getRoleOwnership());
                employeeRole.setStatus(record.isStatus());
                employeeRoleRecord.add(employeeRole);
            }

            loggedInEmployeeRecord.setRoleRecords(employeeRoleRecord);


         return loggedInEmployee;
    }

输出：

    {
  "employeeId": 1,
  "employeeName": "Dhyanandra Singh",
  "employeeEmail": "admin",
  "contactNo": "9893651872",
  "password": "123456",
  "isActive": true,
  "roleRecords": [
    {
      "employeeRoleId": 1,
      "roleOwnership": "overall project",
      "status": true,
      "roleId": 0,
      "roleName": null
    }
  ],
}

问题：

我得到的 json 输出在角色记录列表中不包含角色 ID 和角色名称。

Answer 1

问题是：

EmployeeRoleRecord 类上的 roleId 属性映射为@Transient，这意味着它没有持久化到数据库中，因此 Hibernate 无法获取该字段的结果。

查看您的类建模，我无法确定您要使用 roleId 映射的确切内容，我建议两种可能的方法：

1. 不要在 getEmployeeByEmail 方法上直接返回您的查询。先得到结果，然后迭代，在每条记录上手动设置你想要的roleId；

2. 检查您的模型方案并为 roleId 进行正确映射，它可能应该引用另一个实体，因此请确保正确映射关系以在单个查询中获得结果。

祝你好运。

Answer 2

在 EmployeeRoleRecord 中添加了临时 roleId 和 roleName，然后在服务中进行了一些修改。就像在其中迭代列表设置 roleId 和 roleName 一样。

public Employee getSurveyData(String employeeEmail){

            Employee loggedInEmployee =
                     loginDao.getEmployeeByEmail(employeeEmail);

            Employee  loggedInEmployeeRecord = new Employee();

                loggedInEmployeeRecord.setEmployeeId(loggedInEmployee.getEmployeeId());
                loggedInEmployeeRecord.setEmployeeName(loggedInEmployee.getEmployeeName());
                loggedInEmployeeRecord.setEmployeeEmail(loggedInEmployee.getEmployeeEmail());
                loggedInEmployeeRecord.setContactNo(loggedInEmployee.getContactNo());

                List<EmployeeRoleRecord> employeeRoleRecords = loggedInEmployee.getRoleRecords();

                List<EmployeeRoleRecord> employeeRoleRecord = new  ArrayList<>();

                for(EmployeeRoleRecord record :  employeeRoleRecords){

                    EmployeeRoleRecord employeeRole = new EmployeeRoleRecord();

                    employeeRole.setEmployeeRoleId(employeeRole.getEmployeeRoleId());
                    employeeRole.setRoleId(record.getDescription().getRoleId());
                    employeeRole.setRoleName(record.getDescription().getRoleName());
                    employeeRole.setRoleOwnership(record.getRoleOwnership());
                    employeeRole.setStatus(record.isStatus());
                    employeeRoleRecord.add(employeeRole);
                }

                loggedInEmployeeRecord.setRoleRecords(employeeRoleRecord);


             return loggedInEmployeeRecord;
        }