Spring：不使用 Hibernate 的唯一 ID 验证器

Question

在您进行 POST 时，验证器检查是否有重复 ID 的最佳方法是什么？

我尝试创建自定义验证器，但总是得到 Internal Server Error

{ "时间戳": "2020-04-25T14:37:19.158+0000", “状态”：500， "error": "内部服务器错误", "message": "HV000030: No validator can be found for constraint 'com.omega.mtest.validator.IdConstraint' 验证类型 'java.lang.Integer'。检查 'id' 的配置", “路径”：“/用户” }

这是我的模型类

    public class User {

        @IdConstraint
        @Min(value = 1, message = "ID can't be zero or null")
        @Max(value = 1000000, message = "We collect a billion records")
        private int id;



        @Pattern(regexp = "^[a-zA-Z ]*$", message = "Input doesn't match for a full name")
        private String name;

        @Min(value = 10)
        @Max(value = 120, message = "We didn't expect that age")
        private int age;

        @Pattern(regexp = "^[a-zA-Z ]*$", message = "Input doesn't match for a city name")
        private String city;

        public User(int id, String name, int age, String city) {
            this.id = id;
            this.name = name;
            this.age = age;
            this.city = city;
        }

       //getters
    }

自定义验证器接口：

@Constraint(validatedBy = UserValidator.class)
@Target({ElementType.METHOD, ElementType.FIELD})
@Retention(RUNTIME)
public @interface IdConstraint {

    String message() default "The input list cannot contain two ugual IDs";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

接口的类实现

public class UserValidator implements ConstraintValidator<IdConstraint, List<User>> {

    @Override
    public void initialize(IdConstraint constraintAnnotation) {

    }

    @Override
    public boolean isValid(List<User> users, ConstraintValidatorContext context) {
        if (users.size() == 1) {
            return true;
        } else {
            for (int i = 0; i < users.size(); i++) {
                for (int j = 0; j < users.size(); j++) {
                    if (i != j) {
                        if (users.get(i).getId() == users.get(j).getId()) {
                            return true;
                        }
                    }
                }
            }
            return false;
        }
    }

控制器类：

@Validated
@RestController
public class UsersController {

    @Autowired
    public UserService userService;

    @RequestMapping(value = "/user", method = RequestMethod.POST)
    public ResponseEntity<User> createUser(@Valid @RequestBody User user) {
        return new ResponseEntity<>(userService.createUser(user), HttpStatus.CREATED);
    }

    @ExceptionHandler(ConstraintViolationException.class)
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    ResponseEntity<String> handleConstraintViolationException(ConstraintViolationException e) {
        return new ResponseEntity<>("Not valid due to validation error: " + e.getMessage(), HttpStatus.BAD_REQUEST);
    }

    @RequestMapping(value = "/users", method = RequestMethod.GET)
    public List<User> getUsers() {
        return userService.getAllUsers();
    }

    @RequestMapping(value = "/user/{id}", method = RequestMethod.GET)
    public User getUserById(@PathVariable int id) {
        return userService.findUserById(id);
    }
}

用户服务

public interface UserService {

    List<User> getAllUsers();

    User createUser(User user);

    User findUserById(int id);

    List<User> list();
}

回购

@Component
public class UserRepository implements UserService {

    private List<User> users;

    public UserRepository() {
        users = new ArrayList<>();
    }

    @Override
    public List<User> getAllUsers() {
        return users.stream().collect(Collectors.toList());
    }

    @Override
    public User createUser(User user) {
        users.add(user);
        return user;
    }


    @Override
    public User findUserById(int id) {
        return users.stream()
                .filter(t -> t.getId() == id)
                .findAny()
                .orElse(null);
    }

    @Override
    public List<User> list() {
        return users;
    }
}

Answer 1

首先，你在错误的地方使用了@IdConstraint，这意味着private int id。你必须把它放在List<User>上。当您有用户列表并且两个用户中的任何一个在请求正文中没有相同的 id 时，您的验证器就会工作。 你可以解决这两种方法。

检查就是服务：

在 post 端点中，您使用一个用户作为请求正文。因此，您可以使用存储库的getById() 检查服务中的数据库中是否存在 id。如果存在则引发异常，否则插入。

User user= userRepository.getById(user.getId());
if (ObjectUtils.isEmpty(user)) {
  throw new UserNotFoundException();
}

使用验证器：

在验证器函数中调用存储库并不是更好的方法。 但是，您仍然希望可以这样做。

public class UserIdValidator implements ConstraintValidator<IdConstraint, Integer> {

    @Autowired
    Private UserService userService;

    @Override
    public void initialize(IdConstraint constraintAnnotation) {

    }

    @Override
    public boolean isValid(Integer id, ConstraintValidatorContext context) {
      User user= userService.findUserById(id);
      if (ObjectUtils.isEmpty(user)) {
        return false;
      }
      return true;
    }
}

Answer 2

您的验证人签名不正确。

您在这里验证的不是用户列表，而是一个 Integer 。

这样

public class UserIdValidator implements ConstraintValidator<IdConstraint, Integer> {

那么你必须询问你的服务是否已经使用了这个id。

public class UserIdValidator implements ConstraintValidator<IdConstraint, Integer> {

    @Autowired
    Private UserService userService;

    @Override
    public void initialize(IdConstraint constraintAnnotation) {

    }

    @Override
    public boolean isValid(Integer id, ConstraintValidatorContext context) {
         return !userService.existsById(id);
        }
    }

Answer 3

我是这样做的，而且效果很好：

  @RequestMapping(value = "/user", method = RequestMethod.POST)
public ResponseEntity<User> createUser(@Valid @RequestBody User user) {
    Optional<User> check = userService.findUserById(user.getId());
    if (check.isPresent()) {
        return new ResponseEntity<>(userService.createUser(user), HttpStatus.CREATED);
    }
    return new ResponseEntity<>(null, HttpStatus.BAD_REQUEST);
}



@RequestMapping(value = "/user/{id}", method = RequestMethod.GET)
    public ResponseEntity<User> getUserById(@PathVariable int id) {
        if (userService.findUserById(id).isPresent()) {
            return new ResponseEntity<>(userService.findUserById(id).get(), HttpStatus.OK);
        }
        return new ResponseEntity<>(null, HttpStatus.BAD_REQUEST);
    }