Spring：不使用休眠的唯一ID验证程序

Question

在执行POST时，由验证程序检查以确保没有重复ID的最佳方法是什么？

我试图创建一个自定义验证器，但总是得到一个Internal Server Error

{“ timestamp”：“ 2020-04-25T14：37：19.158 + 0000”，“状态”：500，“错误”：“内部服务器错误”，“ message”：“ HV000030：找不到约束类型'com.omega.mtest.validator.IdConstraint'的验证器，验证类型'java.lang.Integer'。检查'id'的配置”，“路径”：“ /用户”}

这是我的模特班

    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
    }

自定义验证程序界面：

@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);
    }
}

UserService

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

您的验证者签名不正确。

这里您不是验证用户列表，而是一个整数。

喜欢这个

public class UserValidator implements ConstraintValidator<IdConstraint, Integer> {

然后，您必须通过注入服务或存储库来在验证器中恢复用户列表

public class UserValidator implements ConstraintValidator<IdConstraint, Integer> {

    @Autowired
    Private UserService userService;

    @Override
    public void initialize(IdConstraint constraintAnnotation) {

    }

    @Override
    public boolean isValid(Integer id, ConstraintValidatorContext context) {
     List<User> users = userService.list();
        if (users.isEmpty()) {
            return true;
        } else {
            for (int i = 0; i < users.size(); i++) {
              if (users.get(i).getId().equals(id)) {
                   return false;
                        }
                    }
                }
            }
            return true;
        }
    }

Answer 2

首先，您在错误的位置使用@IdConstraint表示private int id。您必须将其放在List<User>上。当您拥有用户列表且两个用户中的任何一个都不具有相同的ID时，验证程序就可以工作。

在发布端点中，您正在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。