java - 如何在 Java Spring 上获取字段变量
问题描述
我的学习项目有一个问题,在“如果条件值为空,然后如果条件值字段为空”的情况下,例如我的代码遵循这些代码:
对于实体Users.java:
@Entity
public class Users {
private Long id;
private String employeeId;
private String fullName;
private String username;
private String password;
...
public Users() {
}
Some Code Setter and Getter....
}
对于实体Employee.java:
@Entity
public Class Employee {
private Long id;
private String employeeId;
private String fullName;
...
public Employee() {
}
Some Code Setter and Getter....
}
然后对于我的类服务,我有使用存储库插入数据员工的案例。如果我们在将数据插入表 Employee 之前有验证数据,我们需要检查表用户不为空,然后字段employeeId应为空。我的代码如下:
对于存储库UserRepo.java和EmployeeRepo.java:
@Repository
public interface EmployeeRepo extends CrudRepository<Employee, Long> {
}
@Repository
public interdace UsersRepo extends CrudRepository<Users, Long> {
@Transactional
@Modifying(clearAutomatically = true, flushAutomatically = true)
@Query("UPDATE Users u SET u.employeeId = :employeeId WHERE u.id = :id")
public void updateEmployeeIdUsers(@Param("id") Long id, @Param("employeeId") String employeeId);
}
对于服务用户Service.java:
@Service("usersService")
public class UsersService {
@Autowired
private UsersRepo repo;
public Optional<Users> findById(Long id) {
return repo.findById(id);
}
public void updateEmployeeIdUsers(Long id, String employeeId) {
repo.updateEmployeeIdUsers(id, employeeId);
}
}
对于服务EmployeeService.java:
@Service("employeeService")
public class EmployeeService {
@Autowired
private EmployeeRepo employeeRepo;
@Autowired
private UsersService userService;
public Employee insertEmployee(Employee employee) throws Exception {
Optional<Users> users = userService.findById(employee.getId());
Users userOptional = new Users(); **//on this my problem**
userOptional.getEmployeeId(); **//on this my problem**
if (!users.isPresent()) {
throw new Exception("User ID : "+ employee.getId() +" Not Founded");
}else if (!(userOptional == null)) { **//on this my problem**
throw new Exception("User employeID : "+ employee.getEmployeeId() +" Already Exist on Users");
}
String str1 = "TEST";
Long idUser = employee.getId();
userService.updateEmployeeIdUsers(idUser, str1);
return employeeRepo.save(employee);
}
}
在此代码上,如果 userOptional 始终为 NULL,则我们在 else 上有问题,我尝试调试以查看 employeeId 的值,只是我看到的始终为 Null。所以对我的问题有任何想法,因为我尝试某些案例总是因我的问题而失败。如果对我的问题有任何想法,请回复这些我的问题。非常感谢您回答我的问题。
解决方案
对于建议的解决方案,我将假设以下内容:
Employee
和之间有关系Users
。- 一个
Employee
只能与一个相关Users
username
是自然的关键Users
employeeId
是自然的关键Employee
所以实体:
@Entity
public class Users {
@Id
// This one is an example, you can use the configuration you need
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator= "users_seq")
@SequenceGenerator(name="users_seq", initialValue=1, allocationSize=1, sequenceName = "users_id_seq")
private Long id;
@Column(name = "fullname")
private String fullName;
// Probably this column should be unique and you need to configure in that way here and in your database
@Column
private String username;
@Column
private String password;
// Getter & setter & constructors
}
@Entity
public class Employee {
@Id
// This one is an example, you can use the configuration you need
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator= "employee_seq")
@SequenceGenerator(name="employee_seq", initialValue=1, allocationSize=1, sequenceName = "employee_id_seq")
private Long id;
/**
* Assuming this is your specific identifier for an employee (not related with database PK)
* If the assumption is correct, this column should be unique and you need to configure in
* that way here and in your database
*/
@Column(name = "employeeid")
private String employeeId;
/**
* Not sure if this relation could be nullable or not
*/
@OneToOne
@JoinColumn(name = "users_id")
private Users users;
// Getter & setter & constructors
}
如您所见,两个实体中都没有“重复列”,并且 和之间存在单向OneToOne
关系。如果您需要双向的,此链接将为您提供帮助:双向Employee
Users
OneToOne
存储库:
@Repository
public interface UsersRepository extends CrudRepository<Users, Long> {
Optional<Users> findByUsername(String username);
}
@Repository
public interface EmployeeRepository extends CrudRepository<Employee, Long> {
Optional<Employee> findByEmployeeId(String employeeId);
}
服务:_
@Service
public class UsersService {
@Autowired
private UsersRepository repository;
public Optional<Users> findByUsername(String username) {
return Optional.ofNullable(username)
.flatMap(repository::findByUsername);
}
public Optional<Users> save(Users user) {
return Optional.ofNullable(user)
.map(repository::save);
}
}
@Service
public class EmployeeService {
@Autowired
private EmployeeRepository repository;
@Autowired
private UsersService usersService;
public Optional<Employee> insert(Employee newEmployee) {
/**
* The next line don't make sense:
*
* Optional<Users> users = userService.findById(employee.getId());
*
* I mean:
*
* 1. Usually, id column is configured with @GeneratedValue and manage by database. So you don't need to ask
* if that value exists or not in Users.
*
* 2. Even if you are including id's values manually in both entities what should be "asked" is:
*
* 2.1 Is there any Users in database with the same username than newEmployee.users.username
* 2.2 Is there any Employee in database with the same employeeId
*
* Both ones, are the natural keys of your entities (and tables in database).
*/
return Optional.ofNullable(newEmployee)
.filter(newEmp -> null != newEmp.getUsers())
.map(newEmp -> {
isNewEmployeeValid(newEmp);
// Required because newEmp.getUsers() is a new entity (taking into account the OneToOne relation)
usersService.save(newEmp.getUsers());
repository.save(newEmp);
return newEmp;
});
}
private void isNewEmployeeValid(Employee newEmployee) {
if (usersService.findByUsername(newEmployee.getUsers().getUsername()).isPresent()) {
throw new RuntimeException("Username: "+ newEmployee.getUsers().getUsername() +" exists in database");
}
if (repository.findByEmployeeId(newEmployee.getEmployeeId()).isPresent()) {
throw new RuntimeException("EmployeeId: "+ newEmployee.getEmployeeId() +" exists in database");
}
}
}
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