JPA一对一双向映射不起作用

• Z时代
• 2024-01-10
• 分类：问答

我有下面的Employees和Departments类，当我做一个从员工到部门类的单向映射时，它的工作正常，我将获得员工详细信息以及部门详细JPA一对一双向映射不起作用

@Entity 
@Table(name="EMPLOYEES") 
public class Employees implements Serializable { 
@Id 
@Column(name="EMPLOYEE_ID") 
private Integer employee_id; 
@Column(name="FIRST_NAME") 
private String first_name; 
@Column(name="LAST_NAME") 
private String last_name; 
@Column(name="EMAIL") 
private String email; 
@Column(name="PHONE_NUMBER") 
private String phone_number; 
@Column(name="HIRE_DATE") 
private Date hire_date; 
@Column(name="JOB_ID") 
private String job_id; 
@Column(name="SALARY") 
private double salary; 
@Column(name="COMMISSION_PCT") 
private String commission_pct; 
@Column(name="MANAGER_ID") 
private String manager_id; 
@OneToOne 
@JoinColumn(name="department_id") 
private Departments departments; 
} 

对于上述映射我正确地得到结果，但是当我把双向定向映射部门类，如下，得到错误而访问员工

@Entity 
@Table(name="DEPARTMENTS") 
public class Departments { 
@Id 
@Column(name="DEPARTMENT_ID") 
private Integer department_id; 
@Column(name="DEPARTMENT_NAME") 
private String department_name; 
@Column(name="MANAGER_ID") 
private String manager_id; 
@Column(name="LOCATION_ID") 
private String location_id; 
@OneToOne(mappedBy="departments") 
private Employees employees; 
public Employees getEmployees() { 
    return employees; 
} 
} 
    org.hibernate.event.internal.DefaultLoadEventListener doOnLoad 
INFO: HHH000327: Error performing load command : org.hibernate.HibernateException: More than one row with the given identifier was found: 90, for class: com.example.demo.entity.Employees 

下面是代码访问e mployees

@RequestMapping(value="/getEmployees",method=RequestMethod.GET) 
public ResponseEntity<List<Employees>> getEmployees(){ 
    System.out.println("Employees are "); 
    List<Employees> employees =(List<Employees>) employeeRepo.findOne(new Integer(100)); 
    //System.out.println(employees.getDepartments()); 
    return new ResponseEntity(employees,HttpStatus.OK); 
} 

同样下面是用于检索其多次与双向映射给出相同的结果（递归结果）

代码的部门用于访问部门

@RequestMapping(value="/getDepartments",method=RequestMethod.GET) 
    public ResponseEntity<Departments> getDepartments(){ 
     System.out.println("Departments are "); 
     Departments dept = (Departments) departmentRepo.findOne(new Integer(10)); 
     return new ResponseEntity(dept,HttpStatus.OK); 
    } 

代码请有人帮助我呢？

回答：

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