在 Spring JPA 中没有通过 Setter 更新表

Question

我是 Spring Boot 和 Spring Data JPA 的新手。所以在这里我试图实现一个示例项目，其中员工有工人列表，同时添加一个新工人有员工详细信息也表明他为特定员工工作。我能够更新工作表并完美地获取详细信息。我也在尝试更新 Employee 表，以便在获取特定员工的同时，我也希望获取与他关联的员工列表。但这并没有发生，到目前为止，我还没有使用任何查询，因为它看起来很简单，我认为保存和设置器会有所帮助。

Employee.Java

@Entity
public class Employee {

@Id
private int empId;

private String empName;
private String location;

@OneToMany
private List<Worker> workers;



public Employee(){

}


public Employee(int empId, String empName, String location) {
    super();
    this.empId = empId;
    this.empName = empName;
    this.location = location;
}

public List<Worker> getWorkers() {
    return workers;
}


public void setWorkers(List<Worker> workers) {
    this.workers = workers;
}


public int getEmpId() {
    return empId;
}
public void setEmpId(int empId) {
    this.empId = empId;
}
public String getEmpName() {
    return empName;
}
public void setEmpName(String empName) {
    this.empName = empName;
}
public String getLocation() {
    return location;
}
public void setLocation(String location) {
    this.location = location;
}


public void setWorkers(Worker worker) {
    this.workers.add(worker);

}


@Override
public String toString() {
    return "Employee [empId=" + empId + ", empName=" + empName + ", location=" + location + ", workers=" + workers
            + "]";
}

/*@Override
public String toString() {
    return "Employee [empId=" + empId + ", empName=" + empName + ", location=" + location + "]";
}*/

Worker.Java

@Entity
public class Worker {

@Id
private int id;

private String name;

@ManyToOne
@JoinColumn(name="empId")
private Employee employee;



public Worker(int id, String name , int empId) {
    super();
    this.id = id;
    this.name = name;
    this.employee = new Employee(empId,"","");
}

public Worker() {
    // TODO Auto-generated constructor stub
}

public Employee getEmployee() {
    return employee;
}

public void setEmployee(Employee employee) {
    this.employee = employee;
}

public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}

WorkerController.Java

@RestController
public class WorkerController {

@Autowired
WorkerRepository workerService;

@Autowired
EmployeeRepository employeeService;



@GetMapping("/employees/{id}/workers")
public List<Worker> getAllWorker(@PathVariable("id") int empId){
    return workerService.findByEmployeeEmpId(empId);
}

@PostMapping("/employees/{id}/workers")
public String addNewEmployee(@RequestParam("name") String name ,
        @RequestParam("workerId") int id , @PathVariable("id") int empId){
     Worker worker = new Worker();
     List<Worker> workers = new ArrayList<Worker>();
     worker.setId(id);
     worker.setName(name);
     worker.setEmployee(new Employee(empId,"",""));
     workerService.save(worker);
     workers.add(worker);
     employeeService.findById(empId).get().setWorkers(workers);
     Employee emp = new Employee();
     emp = employeeService.findById(empId).get();
     return "Successfully added";
     }

     }

添加 worker 后，我检索以下内容作为输出

[
{
    "id": 108,
    "name": "vijay",
    "employee": {
        "empId": 99,
        "empName": "darsha",
        "location": "mumbai",
        "workers": []
    }
},
{
    "id": 110,
    "name": "suraj",
    "employee": {
        "empId": 99,
        "empName": "darsha",
        "location": "mumbai",
        "workers": []
    }
}
]

但是在检索时我可以看到员工表没有更新。有人可以指导我吗？

{
"empId": 99,
"empName": "darsha",
"location": "mumbai",
"workers": []
}

Answer 1

你说：

"...在获取特定员工时，我想要员工列表 与他相关联的也将被取走”

那么你必须在员工方面写一个 OneToMany 关系。您所做的是尝试为每个 Worker 获取一个 Employee ，该 Employee 当然正在工作并且存在于您的 JSON 结果中。

这里是 Emplyees 类方面的 OneToMany 示例：

@OneToMany(mappedBy="employee", fetch=FetchType.EAGER, cascade=CascadeType.ALL)
private List<Worker> worker = new ArrayList<>();

注意：mappedBy 必须在您的 Worker Class 中引用变量 Emplyee employee。

请尝试不同的获取类型。

Answer 2

为什么你没有得到你的@OneToMany 属性是由于默认情况下所有@OneToMany 关联（如列表、集合）的获取类型是惰性的。

为了克服这个问题。将默认的惰性获取更改为急切获取。

修改你的实体映射到这个。

@OneToMany(mappedBy="employee", fetch=FetchType.EAGER, cascade=CascadeType.ALL) private List<Worker> worker = new ArrayList<>();

在获取时，您可能会得到递归映射。为避免这种情况，只需将 @JsonIgnoreProperties 添加到工人类的员工字段中即可。

例子：

@JsonIgnoreProperties("employee")
@ManyToOne
@JoinColumn(name="empId") 
private Employee employee;