Spring-Validation 모범사례

오류메시지를 조금 더 친절하게 안내하기 위한 작업

package com.example.exception.advice;

import com.example.exception.controller.ApiController;
import com.example.exception.dto.Error;

import com.example.exception.dto.ErrorResponse;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.MissingServletRequestParameterException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;

import javax.servlet.http.HttpServletRequest;
import javax.validation.ConstraintViolationException;
import javax.validation.Path;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;


@RestControllerAdvice(basePackageClasses = ApiController.class)
public class ApiControllerAdvice {

    @ExceptionHandler(value = Exception.class)
    public ResponseEntity exception(Exception e){
        System.out.println(e.getClass().getName());
        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("");
    }

    @ExceptionHandler(value = MethodArgumentNotValidException.class)
    public ResponseEntity methodArgumentNotValidException(MethodArgumentNotValidException e,HttpServletRequest httpServletRequest){

        List<Error> errorList = new ArrayList<>();

        BindingResult bindingResult = e.getBindingResult();
        bindingResult.getAllErrors().forEach(error -> {
            FieldError field = (FieldError) error;

            String fieldName = field.getField();
            String message = field.getDefaultMessage();
            String value = field.getRejectedValue().toString();

            Error errorMessage = new Error();
            errorMessage.setField(fieldName);
            errorMessage.setMessage(message);
            errorMessage.setInvalidValue(value);

            errorList.add(errorMessage);
        });

        ErrorResponse errorResponse = new ErrorResponse();
        errorResponse.setErrorList(errorList);
        errorResponse.setMessage("");
        errorResponse.setRequestUrl(httpServletRequest.getRequestURI());
        errorResponse.setStatusCode(HttpStatus.BAD_REQUEST.toString());
        errorResponse.setResultCode("FAIL");

        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(errorResponse);
    }

    @ExceptionHandler(value = ConstraintViolationException.class)
    public ResponseEntity constraintViolationException(ConstraintViolationException e, HttpServletRequest httpServletRequest){

        List<Error> errorList = new ArrayList<>();

        e.getConstraintViolations().forEach(error ->{
            Stream<Path.Node> stream= StreamSupport.stream(error.getPropertyPath().spliterator(),false);
            List<Path.Node> list =stream.collect(Collectors.toList());
            String field=list.get(list.size()-1).getName();
            String message = error .getMessage();
            String invalidvalue=error.getInvalidValue().toString();

            Error errorMessage = new Error();
            errorMessage.setField(field);
            errorMessage.setMessage(message);
            errorMessage.setInvalidValue(invalidvalue);

            errorList.add(errorMessage);
        });

        ErrorResponse errorResponse = new ErrorResponse();
        errorResponse.setErrorList(errorList);
        errorResponse.setMessage("");
        errorResponse.setRequestUrl(httpServletRequest.getRequestURI());
        errorResponse.setStatusCode(HttpStatus.BAD_REQUEST.toString());
        errorResponse.setResultCode("FAIL");

        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(errorResponse);
    }

    @ExceptionHandler(value = MissingServletRequestParameterException.class)
    public  ResponseEntity missingServletRequestParameterException(MissingServletRequestParameterException e, HttpServletRequest httpServletRequest){

        List<Error> errorList = new ArrayList<>();

        String fieldName=e.getParameterName();
        String invalidValue=e.getMessage();

        Error errorMessage = new Error();
        errorMessage.setField(fieldName);
        errorMessage.setMessage(e.getMessage());

        ErrorResponse errorResponse = new ErrorResponse();
        errorResponse.setErrorList(errorList);
        errorResponse.setMessage("");
        errorResponse.setRequestUrl(httpServletRequest.getRequestURI());
        errorResponse.setStatusCode(HttpStatus.BAD_REQUEST.toString());
        errorResponse.setResultCode("FAIL");

        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(errorResponse);
    }
}

각 에러마다 정의하여 깔끔하게 전달할수있다.

package com.example.exception.dto;

import java.util.List;

public class ErrorResponse {

    String statusCode;
    String requestUrl;
    String code;
    String message;
    String resultCode;

    List<Error> errorList;

    public String getStatusCode() {
        return statusCode;
    }

    public void setStatusCode(String statusCode) {
        this.statusCode = statusCode;
    }

    public String getRequestUrl() {
        return requestUrl;
    }

    public void setRequestUrl(String requestUrl) {
        this.requestUrl = requestUrl;
    }

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public String getResultCode() {
        return resultCode;
    }

    public void setResultCode(String resultCode) {
        this.resultCode = resultCode;
    }

    public List<Error> getErrorList() {
        return errorList;
    }

    public void setErrorList(List<Error> errorList) {
        this.errorList = errorList;
    }
}

package com.example.exception.dto;

public class Error {

    private String field;
    private String message;
    private String invalidValue;

    public String getField() {
        return field;
    }

    public void setField(String field) {
        this.field = field;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public String getInvalidValue() {
        return invalidValue;
    }

    public void setInvalidValue(String invalidValue) {
        this.invalidValue = invalidValue;
    }
}

package com.example.exception.controller;

import com.example.exception.dto.User;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;

import javax.validation.Valid;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

@RestController
@RequestMapping("/api/user")
@Validated
public class ApiController {

    @GetMapping("")
    public User get(
            @Size(min=2)
            @RequestParam String name,

            @NotNull
            @Min(1)
            @RequestParam Integer age){
        //required false: RequestParam이 없어도 동작하되 null값이 됨
        User user=new User();
        user.setName(name);
        user.setAge(age);

        return user;
    }

    @PostMapping("")
    public User post(@Valid @RequestBody User user){
        System.out.println(user);
        return user;
    }
}

package com.example.exception.dto;

import javax.validation.constraints.Min;
import javax.validation.constraints.NotEmpty;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

public class User {
    @NotEmpty
    @Size(min=1, max = 10)
    private String name;

    @Min(1)
    @NotNull
    private Integer age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}