Update bean validation

src/main/java/io/spring/api/ArticlesApi.java

@@ -1,19 +1,28 @@
 package io.spring.api;
 
 import com.fasterxml.jackson.annotation.JsonRootName;
-import io.spring.api.exception.InvalidRequestException;
-import io.spring.application.Page;
 import io.spring.application.ArticleQueryService;
+import io.spring.application.Page;
 import io.spring.core.article.Article;
 import io.spring.core.article.ArticleRepository;
 import io.spring.core.user.User;
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.util.HashMap;
+import javax.validation.Constraint;
+import javax.validation.ConstraintValidator;
+import javax.validation.ConstraintValidatorContext;
+import javax.validation.Payload;
+import javax.validation.Valid;
+import javax.validation.constraints.NotBlank;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
-import javax.validation.constraints.NotBlank;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.ResponseEntity;
 import org.springframework.security.core.annotation.AuthenticationPrincipal;
-import org.springframework.validation.BindingResult;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
@@ -21,9 +30,6 @@ import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 
-import javax.validation.Valid;
-import java.util.HashMap;
-
 @RestController
 @RequestMapping(path = "/articles")
 public class ArticlesApi {
@@ -37,45 +43,43 @@ public class ArticlesApi {
   }
 
   @PostMapping
-    public ResponseEntity createArticle(@Valid @RequestBody NewArticleParam newArticleParam,
+  public ResponseEntity createArticle(
-                                        BindingResult bindingResult,
+      @Valid @RequestBody NewArticleParam newArticleParam, @AuthenticationPrincipal User user) {
-                                        @AuthenticationPrincipal User user) {
+    Article article =
-        if (bindingResult.hasErrors()) {
+        new Article(
-            throw new InvalidRequestException(bindingResult);
-        }
-
-        if (articleQueryService.findBySlug(Article.toSlug(newArticleParam.getTitle()), null).isPresent()) {
-            bindingResult.rejectValue("title", "DUPLICATED", "article name exists");
-            throw new InvalidRequestException(bindingResult);
-        }
-
-        Article article = new Article(
             newArticleParam.getTitle(),
             newArticleParam.getDescription(),
             newArticleParam.getBody(),
             newArticleParam.getTagList(),
             user.getId());
     articleRepository.save(article);
-        return ResponseEntity.ok(new HashMap<String, Object>() {{
+    return ResponseEntity.ok(
+        new HashMap<String, Object>() {
+          {
             put("article", articleQueryService.findById(article.getId(), user).get());
-        }});
+          }
+        });
   }
 
   @GetMapping(path = "feed")
-    public ResponseEntity getFeed(@RequestParam(value = "offset", defaultValue = "0") int offset,
+  public ResponseEntity getFeed(
+      @RequestParam(value = "offset", defaultValue = "0") int offset,
       @RequestParam(value = "limit", defaultValue = "20") int limit,
       @AuthenticationPrincipal User user) {
     return ResponseEntity.ok(articleQueryService.findUserFeed(user, new Page(offset, limit)));
   }
 
   @GetMapping
-    public ResponseEntity getArticles(@RequestParam(value = "offset", defaultValue = "0") int offset,
+  public ResponseEntity getArticles(
+      @RequestParam(value = "offset", defaultValue = "0") int offset,
       @RequestParam(value = "limit", defaultValue = "20") int limit,
       @RequestParam(value = "tag", required = false) String tag,
       @RequestParam(value = "favorited", required = false) String favoritedBy,
       @RequestParam(value = "author", required = false) String author,
       @AuthenticationPrincipal User user) {
-        return ResponseEntity.ok(articleQueryService.findRecentArticles(tag, author, favoritedBy, new Page(offset, limit), user));
+    return ResponseEntity.ok(
+        articleQueryService.findRecentArticles(
+            tag, author, favoritedBy, new Page(offset, limit), user));
   }
 }
 
@@ -84,10 +88,37 @@ public class ArticlesApi {
 @NoArgsConstructor
 class NewArticleParam {
   @NotBlank(message = "can't be empty")
+  @DuplicatedArticleConstraint
   private String title;
+
   @NotBlank(message = "can't be empty")
   private String description;
+
   @NotBlank(message = "can't be empty")
   private String body;
+
   private String[] tagList;
 }
+
+@Documented
+@Constraint(validatedBy = DuplicatedArticleValidator.class)
+@Target({ElementType.METHOD, ElementType.FIELD, ElementType.PARAMETER, ElementType.TYPE_USE})
+@Retention(RetentionPolicy.RUNTIME)
+@interface DuplicatedArticleConstraint {
+  String message() default "article name exists";
+
+  Class<?>[] groups() default {};
+
+  Class<? extends Payload>[] payload() default {};
+}
+
+class DuplicatedArticleValidator
+    implements ConstraintValidator<DuplicatedArticleConstraint, String> {
+
+  @Autowired private ArticleQueryService articleQueryService;
+
+  @Override
+  public boolean isValid(String value, ConstraintValidatorContext context) {
+    return !articleQueryService.findBySlug(Article.toSlug(value), null).isPresent();
+  }
+}

src/main/java/io/spring/api/CommentsApi.java

@@ -1,24 +1,26 @@
 package io.spring.api;
 
 import com.fasterxml.jackson.annotation.JsonRootName;
-import io.spring.api.exception.InvalidRequestException;
 import io.spring.api.exception.NoAuthorizationException;
 import io.spring.api.exception.ResourceNotFoundException;
-import io.spring.core.service.AuthorizationService;
-import io.spring.application.data.CommentData;
 import io.spring.application.CommentQueryService;
+import io.spring.application.data.CommentData;
 import io.spring.core.article.Article;
 import io.spring.core.article.ArticleRepository;
 import io.spring.core.comment.Comment;
 import io.spring.core.comment.CommentRepository;
+import io.spring.core.service.AuthorizationService;
 import io.spring.core.user.User;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import javax.validation.Valid;
+import javax.validation.constraints.NotBlank;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
-import javax.validation.constraints.NotBlank;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.ResponseEntity;
 import org.springframework.security.core.annotation.AuthenticationPrincipal;
-import org.springframework.validation.BindingResult;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
@@ -27,11 +29,6 @@ import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.RestController;
 
-import javax.validation.Valid;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
 @RestController
 @RequestMapping(path = "/articles/{slug}/comments")
 public class CommentsApi {
@@ -40,7 +37,8 @@ public class CommentsApi {
   private CommentQueryService commentQueryService;
 
   @Autowired
-    public CommentsApi(ArticleRepository articleRepository,
+  public CommentsApi(
+      ArticleRepository articleRepository,
       CommentRepository commentRepository,
       CommentQueryService commentQueryService) {
     this.articleRepository = articleRepository;
@@ -49,51 +47,62 @@ public class CommentsApi {
   }
 
   @PostMapping
-    public ResponseEntity<?> createComment(@PathVariable("slug") String slug,
+  public ResponseEntity<?> createComment(
+      @PathVariable("slug") String slug,
       @AuthenticationPrincipal User user,
-                                                     @Valid @RequestBody NewCommentParam newCommentParam,
+      @Valid @RequestBody NewCommentParam newCommentParam) {
-                                                     BindingResult bindingResult) {
     Article article = findArticle(slug);
-        if (bindingResult.hasErrors()) {
-            throw new InvalidRequestException(bindingResult);
-        }
     Comment comment = new Comment(newCommentParam.getBody(), user.getId(), article.getId());
     commentRepository.save(comment);
-        return ResponseEntity.status(201).body(commentResponse(commentQueryService.findById(comment.getId(), user).get()));
+    return ResponseEntity.status(201)
+        .body(commentResponse(commentQueryService.findById(comment.getId(), user).get()));
   }
 
   @GetMapping
-    public ResponseEntity getComments(@PathVariable("slug") String slug,
+  public ResponseEntity getComments(
-                                      @AuthenticationPrincipal User user) {
+      @PathVariable("slug") String slug, @AuthenticationPrincipal User user) {
     Article article = findArticle(slug);
     List<CommentData> comments = commentQueryService.findByArticleId(article.getId(), user);
-        return ResponseEntity.ok(new HashMap<String, Object>() {{
+    return ResponseEntity.ok(
+        new HashMap<String, Object>() {
+          {
             put("comments", comments);
-        }});
+          }
+        });
   }
 
   @RequestMapping(path = "{id}", method = RequestMethod.DELETE)
-    public ResponseEntity deleteComment(@PathVariable("slug") String slug,
+  public ResponseEntity deleteComment(
+      @PathVariable("slug") String slug,
       @PathVariable("id") String commentId,
       @AuthenticationPrincipal User user) {
     Article article = findArticle(slug);
-        return commentRepository.findById(article.getId(), commentId).map(comment -> {
+    return commentRepository
+        .findById(article.getId(), commentId)
+        .map(
+            comment -> {
               if (!AuthorizationService.canWriteComment(user, article, comment)) {
                 throw new NoAuthorizationException();
               }
               commentRepository.remove(comment);
               return ResponseEntity.noContent().build();
-        }).orElseThrow(ResourceNotFoundException::new);
+            })
+        .orElseThrow(ResourceNotFoundException::new);
   }
 
   private Article findArticle(String slug) {
-        return articleRepository.findBySlug(slug).map(article -> article).orElseThrow(ResourceNotFoundException::new);
+    return articleRepository
+        .findBySlug(slug)
+        .map(article -> article)
+        .orElseThrow(ResourceNotFoundException::new);
   }
 
   private Map<String, Object> commentResponse(CommentData commentData) {
-        return new HashMap<String, Object>() {{
+    return new HashMap<String, Object>() {
+      {
         put("comment", commentData);
-        }};
+      }
+    };
   }
 }
 

src/main/java/io/spring/api/CurrentUserApi.java

@@ -1,19 +1,28 @@
 package io.spring.api;
 
 import com.fasterxml.jackson.annotation.JsonRootName;
-import io.spring.api.exception.InvalidRequestException;
 import io.spring.application.UserQueryService;
-import io.spring.application.data.UserWithToken;
 import io.spring.application.data.UserData;
+import io.spring.application.data.UserWithToken;
 import io.spring.core.user.User;
 import io.spring.core.user.UserRepository;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.util.HashMap;
+import java.util.Map;
+import javax.validation.Constraint;
+import javax.validation.ConstraintValidator;
+import javax.validation.ConstraintValidatorContext;
+import javax.validation.Valid;
+import javax.validation.constraints.Email;
+import lombok.AllArgsConstructor;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
-import javax.validation.constraints.Email;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.ResponseEntity;
 import org.springframework.security.core.annotation.AuthenticationPrincipal;
-import org.springframework.validation.BindingResult;
+import org.springframework.stereotype.Service;
+import org.springframework.validation.annotation.Validated;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PutMapping;
 import org.springframework.web.bind.annotation.RequestBody;
@@ -21,79 +30,127 @@ import org.springframework.web.bind.annotation.RequestHeader;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
-import javax.validation.Valid;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Optional;
-
 @RestController
 @RequestMapping(path = "/user")
 public class CurrentUserApi {
+
   private UserQueryService userQueryService;
-    private UserRepository userRepository;
+  private UserService userService;
 
   @Autowired
-    public CurrentUserApi(UserQueryService userQueryService, UserRepository userRepository) {
+  public CurrentUserApi(UserQueryService userQueryService, UserService userService) {
     this.userQueryService = userQueryService;
-        this.userRepository = userRepository;
+    this.userService = userService;
   }
 
   @GetMapping
-    public ResponseEntity currentUser(@AuthenticationPrincipal User currentUser,
+  public ResponseEntity currentUser(
+      @AuthenticationPrincipal User currentUser,
       @RequestHeader(value = "Authorization") String authorization) {
     UserData userData = userQueryService.findById(currentUser.getId()).get();
-        return ResponseEntity.ok(userResponse(
+    return ResponseEntity.ok(
-            new UserWithToken(userData, authorization.split(" ")[1])
+        userResponse(new UserWithToken(userData, authorization.split(" ")[1])));
-        ));
   }
 
   @PutMapping
-    public ResponseEntity updateProfile(@AuthenticationPrincipal User currentUser,
+  public ResponseEntity updateProfile(
+      @AuthenticationPrincipal User currentUser,
       @RequestHeader("Authorization") String token,
-                                        @Valid @RequestBody UpdateUserParam updateUserParam,
+      @Valid @RequestBody UpdateUserParam updateUserParam) {
-                                        BindingResult bindingResult) {
-        if (bindingResult.hasErrors()) {
-            throw new InvalidRequestException(bindingResult);
-        }
-        checkUniquenessOfUsernameAndEmail(currentUser, updateUserParam, bindingResult);
 
-        currentUser.update(
+    userService.updateUser(new UpdateUserCommand(currentUser, updateUserParam));
+    UserData userData = userQueryService.findById(currentUser.getId()).get();
+    return ResponseEntity.ok(userResponse(new UserWithToken(userData, token.split(" ")[1])));
+  }
+
+  private Map<String, Object> userResponse(UserWithToken userWithToken) {
+    return new HashMap<String, Object>() {
+      {
+        put("user", userWithToken);
+      }
+    };
+  }
+}
+
+@Validated
+@Service
+class UserService {
+
+  private UserRepository userRepository;
+
+  @Autowired
+  public UserService(UserRepository userRepository) {
+    this.userRepository = userRepository;
+  }
+
+  public void updateUser(@Valid UpdateUserCommand command) {
+    User user = command.getTargetUser();
+    UpdateUserParam updateUserParam = command.getParam();
+    user.update(
         updateUserParam.getEmail(),
         updateUserParam.getUsername(),
         updateUserParam.getPassword(),
         updateUserParam.getBio(),
         updateUserParam.getImage());
-        userRepository.save(currentUser);
+    userRepository.save(user);
-        UserData userData = userQueryService.findById(currentUser.getId()).get();
-        return ResponseEntity.ok(userResponse(
-            new UserWithToken(userData, token.split(" ")[1])
-        ));
   }
+}
 
-    private void checkUniquenessOfUsernameAndEmail(User currentUser, UpdateUserParam updateUserParam, BindingResult bindingResult) {
+@Getter
-        if (!"".equals(updateUserParam.getUsername())) {
+@AllArgsConstructor
-            Optional<User> byUsername = userRepository.findByUsername(updateUserParam.getUsername());
+@UpdateUserConstraint
-            if (byUsername.isPresent() && !byUsername.get().equals(currentUser)) {
+class UpdateUserCommand {
-                bindingResult.rejectValue("username", "DUPLICATED", "username already exist");
-            }
-        }
 
-        if (!"".equals(updateUserParam.getEmail())) {
+  private User targetUser;
-            Optional<User> byEmail = userRepository.findByEmail(updateUserParam.getEmail());
+  private UpdateUserParam param;
-            if (byEmail.isPresent() && !byEmail.get().equals(currentUser)) {
+}
-                bindingResult.rejectValue("email", "DUPLICATED", "email already exist");
-            }
-        }
 
-        if (bindingResult.hasErrors()) {
+@Constraint(validatedBy = UpdateUserValidator.class)
-            throw new InvalidRequestException(bindingResult);
+@Retention(RetentionPolicy.RUNTIME)
-        }
+@interface UpdateUserConstraint {
-    }
 
-    private Map<String, Object> userResponse(UserWithToken userWithToken) {
+  String message() default "invalid update param";
-        return new HashMap<String, Object>() {{
+
-            put("user", userWithToken);
+  Class[] groups() default {};
-        }};
+
+  Class[] payload() default {};
+}
+
+class UpdateUserValidator implements ConstraintValidator<UpdateUserConstraint, UpdateUserCommand> {
+
+  @Autowired private UserRepository userRepository;
+
+  @Override
+  public boolean isValid(UpdateUserCommand value, ConstraintValidatorContext context) {
+    String inputEmail = value.getParam().getEmail();
+    String inputUsername = value.getParam().getUsername();
+    final User targetUser = value.getTargetUser();
+
+    boolean isEmailValid =
+        userRepository.findByEmail(inputEmail).map(user -> user.equals(targetUser)).orElse(true);
+    boolean isUsernameValid =
+        userRepository
+            .findByUsername(inputUsername)
+            .map(user -> user.equals(targetUser))
+            .orElse(true);
+    if (isEmailValid && isUsernameValid) {
+      return true;
+    } else {
+      context.disableDefaultConstraintViolation();
+      if (!isEmailValid) {
+        context
+            .buildConstraintViolationWithTemplate("email already exist")
+            .addPropertyNode("email")
+            .addConstraintViolation();
+      }
+      if (!isUsernameValid) {
+        context
+            .buildConstraintViolationWithTemplate("username already exist")
+            .addPropertyNode("username")
+            .addConstraintViolation();
+      }
+      return false;
+    }
   }
 }
 
@@ -101,8 +158,10 @@ public class CurrentUserApi {
 @JsonRootName("user")
 @NoArgsConstructor
 class UpdateUserParam {
+
   @Email(message = "should be an email")
   private String email = "";
+
   private String password = "";
   private String username = "";
   private String bio = "";

src/main/java/io/spring/api/UsersApi.java

@@ -1,32 +1,36 @@
 package io.spring.api;
 
+import static org.springframework.web.bind.annotation.RequestMethod.POST;
+
 import com.fasterxml.jackson.annotation.JsonRootName;
-import io.spring.api.exception.InvalidRequestException;
+import io.spring.api.exception.InvalidAuthenticationException;
 import io.spring.application.UserQueryService;
-import io.spring.application.data.UserWithToken;
 import io.spring.application.data.UserData;
+import io.spring.application.data.UserWithToken;
 import io.spring.core.service.JwtService;
 import io.spring.core.user.EncryptService;
 import io.spring.core.user.User;
 import io.spring.core.user.UserRepository;
-import lombok.Getter;
+import java.lang.annotation.Retention;
-import lombok.NoArgsConstructor;
+import java.lang.annotation.RetentionPolicy;
-import javax.validation.constraints.Email;
-import javax.validation.constraints.NotBlank;
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.beans.factory.annotation.Value;
-import org.springframework.http.ResponseEntity;
-import org.springframework.validation.BindingResult;
-import org.springframework.web.bind.annotation.RequestBody;
-import org.springframework.web.bind.annotation.RequestMapping;
-import org.springframework.web.bind.annotation.RestController;
-
-import javax.validation.Valid;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Optional;
-
+import javax.validation.Constraint;
-import static org.springframework.web.bind.annotation.RequestMethod.POST;
+import javax.validation.ConstraintValidator;
+import javax.validation.ConstraintValidatorContext;
+import javax.validation.Payload;
+import javax.validation.Valid;
+import javax.validation.constraints.Email;
+import javax.validation.constraints.NotBlank;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
 
 @RestController
 public class UsersApi {
@@ -37,7 +41,8 @@ public class UsersApi {
   private JwtService jwtService;
 
   @Autowired
-    public UsersApi(UserRepository userRepository,
+  public UsersApi(
+      UserRepository userRepository,
       UserQueryService userQueryService,
       EncryptService encryptService,
       @Value("${image.default}") String defaultImage,
@@ -50,10 +55,9 @@ public class UsersApi {
   }
 
   @RequestMapping(path = "/users", method = POST)
-    public ResponseEntity createUser(@Valid @RequestBody RegisterParam registerParam, BindingResult bindingResult) {
+  public ResponseEntity createUser(@Valid @RequestBody RegisterParam registerParam) {
-        checkInput(registerParam, bindingResult);
+    User user =
-
+        new User(
-        User user = new User(
             registerParam.getEmail(),
             registerParam.getUsername(),
             encryptService.encrypt(registerParam.getPassword()),
@@ -61,42 +65,70 @@ public class UsersApi {
             defaultImage);
     userRepository.save(user);
     UserData userData = userQueryService.findById(user.getId()).get();
-        return ResponseEntity.status(201).body(userResponse(new UserWithToken(userData, jwtService.toToken(user))));
+    return ResponseEntity.status(201)
-    }
+        .body(userResponse(new UserWithToken(userData, jwtService.toToken(user))));
-
-    private void checkInput(@Valid @RequestBody RegisterParam registerParam, BindingResult bindingResult) {
-        if (bindingResult.hasErrors()) {
-            throw new InvalidRequestException(bindingResult);
-        }
-        if (userRepository.findByUsername(registerParam.getUsername()).isPresent()) {
-            bindingResult.rejectValue("username", "DUPLICATED", "duplicated username");
-        }
-
-        if (userRepository.findByEmail(registerParam.getEmail()).isPresent()) {
-            bindingResult.rejectValue("email", "DUPLICATED", "duplicated email");
-        }
-
-        if (bindingResult.hasErrors()) {
-            throw new InvalidRequestException(bindingResult);
-        }
   }
 
   @RequestMapping(path = "/users/login", method = POST)
-    public ResponseEntity userLogin(@Valid @RequestBody LoginParam loginParam, BindingResult bindingResult) {
+  public ResponseEntity userLogin(@Valid @RequestBody LoginParam loginParam) {
     Optional<User> optional = userRepository.findByEmail(loginParam.getEmail());
-        if (optional.isPresent() && encryptService.check(loginParam.getPassword(), optional.get().getPassword())) {
+    if (optional.isPresent()
+        && encryptService.check(loginParam.getPassword(), optional.get().getPassword())) {
       UserData userData = userQueryService.findById(optional.get().getId()).get();
-            return ResponseEntity.ok(userResponse(new UserWithToken(userData, jwtService.toToken(optional.get()))));
+      return ResponseEntity.ok(
+          userResponse(new UserWithToken(userData, jwtService.toToken(optional.get()))));
     } else {
-            bindingResult.rejectValue("password", "INVALID", "invalid email or password");
+      throw new InvalidAuthenticationException();
-            throw new InvalidRequestException(bindingResult);
     }
   }
 
   private Map<String, Object> userResponse(UserWithToken userWithToken) {
-        return new HashMap<String, Object>() {{
+    return new HashMap<String, Object>() {
+      {
         put("user", userWithToken);
-        }};
+      }
+    };
+  }
+}
+
+@Constraint(validatedBy = DuplicatedEmailValidator.class)
+@Retention(RetentionPolicy.RUNTIME)
+@interface DuplicatedEmailConstraint {
+  String message() default "duplicated email";
+
+  Class<?>[] groups() default {};
+
+  Class<? extends Payload>[] payload() default {};
+}
+
+class DuplicatedEmailValidator implements ConstraintValidator<DuplicatedEmailConstraint, String> {
+
+  @Autowired private UserRepository userRepository;
+
+  @Override
+  public boolean isValid(String value, ConstraintValidatorContext context) {
+    return (value == null || value.isEmpty()) || !userRepository.findByEmail(value).isPresent();
+  }
+}
+
+@Constraint(validatedBy = DuplicatedUsernameValidator.class)
+@Retention(RetentionPolicy.RUNTIME)
+@interface DuplicatedUsernameConstraint {
+  String message() default "duplicated username";
+
+  Class<?>[] groups() default {};
+
+  Class<? extends Payload>[] payload() default {};
+}
+
+class DuplicatedUsernameValidator
+    implements ConstraintValidator<DuplicatedUsernameConstraint, String> {
+
+  @Autowired private UserRepository userRepository;
+
+  @Override
+  public boolean isValid(String value, ConstraintValidatorContext context) {
+    return (value == null || value.isEmpty()) || !userRepository.findByUsername(value).isPresent();
   }
 }
 
@@ -107,6 +139,7 @@ class LoginParam {
   @NotBlank(message = "can't be empty")
   @Email(message = "should be an email")
   private String email;
+
   @NotBlank(message = "can't be empty")
   private String password;
 }
@@ -117,9 +150,13 @@ class LoginParam {
 class RegisterParam {
   @NotBlank(message = "can't be empty")
   @Email(message = "should be an email")
+  @DuplicatedEmailConstraint
   private String email;
+
   @NotBlank(message = "can't be empty")
+  @DuplicatedUsernameConstraint
   private String username;
+
   @NotBlank(message = "can't be empty")
   private String password;
 }

src/main/java/io/spring/api/exception/CustomizeExceptionHandler.java

@@ -1,18 +1,26 @@
 package io.spring.api.exception;
 
+import static org.springframework.http.HttpStatus.UNPROCESSABLE_ENTITY;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.stream.Collectors;
+import javax.validation.ConstraintViolation;
+import javax.validation.ConstraintViolationException;
 import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.MethodArgumentNotValidException;
 import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.ResponseStatus;
 import org.springframework.web.bind.annotation.RestControllerAdvice;
 import org.springframework.web.context.request.WebRequest;
 import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
 
-import java.util.List;
-import java.util.stream.Collectors;
-
-import static org.springframework.http.HttpStatus.UNPROCESSABLE_ENTITY;
-
 @RestControllerAdvice
 public class CustomizeExceptionHandler extends ResponseEntityExceptionHandler {
 
@@ -20,12 +28,16 @@ public class CustomizeExceptionHandler extends ResponseEntityExceptionHandler {
   public ResponseEntity<Object> handleInvalidRequest(RuntimeException e, WebRequest request) {
     InvalidRequestException ire = (InvalidRequestException) e;
 
-        List<FieldErrorResource> errorResources = ire.getErrors().getFieldErrors().stream().map(fieldError ->
+    List<FieldErrorResource> errorResources =
+        ire.getErrors().getFieldErrors().stream()
+            .map(
+                fieldError ->
                     new FieldErrorResource(
                         fieldError.getObjectName(),
                         fieldError.getField(),
                         fieldError.getCode(),
-                fieldError.getDefaultMessage())).collect(Collectors.toList());
+                        fieldError.getDefaultMessage()))
+            .collect(Collectors.toList());
 
     ErrorResource error = new ErrorResource(errorResources);
 
@@ -34,4 +46,64 @@ public class CustomizeExceptionHandler extends ResponseEntityExceptionHandler {
 
     return handleExceptionInternal(e, error, headers, UNPROCESSABLE_ENTITY, request);
   }
+
+  @ExceptionHandler(InvalidAuthenticationException.class)
+  public ResponseEntity<Object> handleInvalidAuthentication(
+      InvalidAuthenticationException e, WebRequest request) {
+    return ResponseEntity.status(UNPROCESSABLE_ENTITY)
+        .body(
+            new HashMap<String, Object>() {
+              {
+                put("message", e.getMessage());
+              }
+            });
+  }
+
+  @Override
+  protected ResponseEntity<Object> handleMethodArgumentNotValid(
+      MethodArgumentNotValidException e,
+      HttpHeaders headers,
+      HttpStatus status,
+      WebRequest request) {
+    List<FieldErrorResource> errorResources =
+        e.getBindingResult().getFieldErrors().stream()
+            .map(
+                fieldError ->
+                    new FieldErrorResource(
+                        fieldError.getObjectName(),
+                        fieldError.getField(),
+                        fieldError.getCode(),
+                        fieldError.getDefaultMessage()))
+            .collect(Collectors.toList());
+
+    return ResponseEntity.status(UNPROCESSABLE_ENTITY).body(new ErrorResource(errorResources));
+  }
+
+  @ExceptionHandler({ConstraintViolationException.class})
+  @ResponseStatus(UNPROCESSABLE_ENTITY)
+  @ResponseBody
+  public ErrorResource handleConstraintViolation(
+      ConstraintViolationException ex, WebRequest request) {
+    List<FieldErrorResource> errors = new ArrayList<>();
+    for (ConstraintViolation<?> violation : ex.getConstraintViolations()) {
+      FieldErrorResource fieldErrorResource =
+          new FieldErrorResource(
+              violation.getRootBeanClass().getName(),
+              getParam(violation.getPropertyPath().toString()),
+              violation.getConstraintDescriptor().getAnnotation().annotationType().getSimpleName(),
+              violation.getMessage());
+      errors.add(fieldErrorResource);
+    }
+
+    return new ErrorResource(errors);
+  }
+
+  private String getParam(String s) {
+    String[] splits = s.split("\\.");
+    if (splits.length == 1) {
+      return s;
+    } else {
+      return String.join(".", Arrays.copyOfRange(splits, 2, splits.length));
+    }
+  }
 }

src/main/java/io/spring/api/exception/InvalidAuthenticationException.java

@@ -0,0 +1,8 @@
+package io.spring.api.exception;
+
+public class InvalidAuthenticationException extends RuntimeException {
+
+  public InvalidAuthenticationException() {
+    super("invalid email or password");
+  }
+}

src/test/java/io/spring/api/ArticlesApiTest.java

@@ -1,5 +1,12 @@
 package io.spring.api;
 
+import static io.restassured.module.mockmvc.RestAssuredMockMvc.given;
+import static org.hamcrest.core.IsEqual.equalTo;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
 import io.restassured.module.mockmvc.RestAssuredMockMvc;
 import io.spring.JacksonCustomizations;
 import io.spring.api.security.WebSecurityConfig;
@@ -8,6 +15,10 @@ import io.spring.application.data.ArticleData;
 import io.spring.application.data.ProfileData;
 import io.spring.core.article.Article;
 import io.spring.core.article.ArticleRepository;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
 import org.joda.time.DateTime;
 import org.junit.Before;
 import org.junit.Test;
@@ -17,30 +28,14 @@ import org.springframework.boot.test.mock.mockito.MockBean;
 import org.springframework.context.annotation.Import;
 import org.springframework.test.web.servlet.MockMvc;
 
-import java.util.Arrays;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Optional;
-
-import static io.restassured.module.mockmvc.RestAssuredMockMvc.given;
-import static org.hamcrest.core.IsEqual.equalTo;
-import static org.mockito.ArgumentMatchers.any;
-import static org.mockito.ArgumentMatchers.eq;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.when;
-
 @WebMvcTest({ArticlesApi.class})
 @Import({WebSecurityConfig.class, JacksonCustomizations.class})
 public class ArticlesApiTest extends TestWithCurrentUser {
-    @Autowired
+  @Autowired private MockMvc mvc;
-    private MockMvc mvc;
 
-    @MockBean
+  @MockBean private ArticleRepository articleRepository;
-    private ArticleRepository articleRepository;
 
-    @MockBean
+  @MockBean private ArticleQueryService articleQueryService;
-    private ArticleQueryService articleQueryService;
 
   @Override
   @Before
@@ -58,7 +53,8 @@ public class ArticlesApiTest extends TestWithCurrentUser {
     String[] tagList = {"reactjs", "angularjs", "dragons"};
     Map<String, Object> param = prepareParam(title, description, body, tagList);
 
-        ArticleData articleData = new ArticleData(
+    ArticleData articleData =
+        new ArticleData(
             "123",
             slug,
             title,
@@ -71,7 +67,8 @@ public class ArticlesApiTest extends TestWithCurrentUser {
             Arrays.asList(tagList),
             new ProfileData("userid", user.getUsername(), user.getBio(), user.getImage(), false));
 
-        when(articleQueryService.findBySlug(eq(Article.toSlug(title)), any())).thenReturn(Optional.empty());
+    when(articleQueryService.findBySlug(eq(Article.toSlug(title)), any()))
+        .thenReturn(Optional.empty());
 
     when(articleQueryService.findById(any(), any())).thenReturn(Optional.of(articleData));
 
@@ -111,7 +108,6 @@ public class ArticlesApiTest extends TestWithCurrentUser {
         .then()
         .statusCode(422)
         .body("errors.body[0]", equalTo("can't be empty"));
-
   }
 
   @Test
@@ -123,7 +119,8 @@ public class ArticlesApiTest extends TestWithCurrentUser {
     String[] tagList = {"reactjs", "angularjs", "dragons"};
     Map<String, Object> param = prepareParam(title, description, body, tagList);
 
-        ArticleData articleData = new ArticleData(
+    ArticleData articleData =
+        new ArticleData(
             "123",
             slug,
             title,
@@ -136,7 +133,8 @@ public class ArticlesApiTest extends TestWithCurrentUser {
             Arrays.asList(tagList),
             new ProfileData("userid", user.getUsername(), user.getBio(), user.getImage(), false));
 
-        when(articleQueryService.findBySlug(eq(Article.toSlug(title)), any())).thenReturn(Optional.of(articleData));
+    when(articleQueryService.findBySlug(eq(Article.toSlug(title)), any()))
+        .thenReturn(Optional.of(articleData));
 
     when(articleQueryService.findById(any(), any())).thenReturn(Optional.of(articleData));
 
@@ -146,19 +144,26 @@ public class ArticlesApiTest extends TestWithCurrentUser {
         .body(param)
         .when()
         .post("/articles")
+        .prettyPeek()
         .then()
         .statusCode(422);
-
   }
 
-    private HashMap<String, Object> prepareParam(final String title, final String description, final String body, final String[] tagList) {
+  private HashMap<String, Object> prepareParam(
-        return new HashMap<String, Object>() {{
+      final String title, final String description, final String body, final String[] tagList) {
-            put("article", new HashMap<String, Object>() {{
+    return new HashMap<String, Object>() {
+      {
+        put(
+            "article",
+            new HashMap<String, Object>() {
+              {
                 put("title", title);
                 put("description", description);
                 put("body", body);
                 put("tagList", tagList);
-            }});
+              }
-        }};
+            });
+      }
+    };
   }
 }

src/test/java/io/spring/api/CurrentUserApiTest.java

@@ -1,37 +1,40 @@
 package io.spring.api;
 
-import io.restassured.module.mockmvc.RestAssuredMockMvc;
-import io.spring.JacksonCustomizations;
-import io.spring.api.security.WebSecurityConfig;
-import io.spring.application.UserQueryService;
-import io.spring.core.user.User;
-import org.junit.Before;
-import org.junit.Test;
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
-import org.springframework.boot.test.mock.mockito.MockBean;
-import org.springframework.context.annotation.Import;
-import org.springframework.test.web.servlet.MockMvc;
-
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Optional;
-
 import static io.restassured.module.mockmvc.RestAssuredMockMvc.given;
 import static org.hamcrest.core.IsEqual.equalTo;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.when;
 
+import io.restassured.module.mockmvc.RestAssuredMockMvc;
+import io.spring.JacksonCustomizations;
+import io.spring.api.security.WebSecurityConfig;
+import io.spring.application.UserQueryService;
+import io.spring.core.user.User;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+import org.junit.Before;
+import org.junit.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.context.annotation.Import;
+import org.springframework.test.web.servlet.MockMvc;
+
 @WebMvcTest(CurrentUserApi.class)
-@Import({WebSecurityConfig.class, JacksonCustomizations.class})
+@Import({
+  WebSecurityConfig.class,
+  JacksonCustomizations.class,
+  UserService.class,
+  ValidationAutoConfiguration.class
+})
 public class CurrentUserApiTest extends TestWithCurrentUser {
 
-    @Autowired
+  @Autowired private MockMvc mvc;
-    private MockMvc mvc;
 
-    @MockBean
+  @MockBean private UserQueryService userQueryService;
-    private UserQueryService userQueryService;
 
   @Override
   @Before
@@ -60,13 +63,7 @@ public class CurrentUserApiTest extends TestWithCurrentUser {
 
   @Test
   public void should_get_401_without_token() throws Exception {
-        given()
+    given().contentType("application/json").when().get("/user").then().statusCode(401);
-            .contentType("application/json")
-            .when()
-            .get("/user")
-            .then()
-            .statusCode(401);
-
   }
 
   @Test
@@ -88,13 +85,20 @@ public class CurrentUserApiTest extends TestWithCurrentUser {
     String newBio = "updated";
     String newUsername = "newusernamee";
 
-        Map<String, Object> param = new HashMap<String, Object>() {{
+    Map<String, Object> param =
-            put("user", new HashMap<String, Object>() {{
+        new HashMap<String, Object>() {
+          {
+            put(
+                "user",
+                new HashMap<String, Object>() {
+                  {
                     put("email", newEmail);
                     put("bio", newBio);
                     put("username", newUsername);
-            }});
+                  }
-        }};
+                });
+          }
+        };
 
     when(userRepository.findByUsername(eq(newUsername))).thenReturn(Optional.empty());
     when(userRepository.findByEmail(eq(newEmail))).thenReturn(Optional.empty());
@@ -119,7 +123,8 @@ public class CurrentUserApiTest extends TestWithCurrentUser {
 
     Map<String, Object> param = prepareUpdateParam(newEmail, newBio, newUsername);
 
-        when(userRepository.findByEmail(eq(newEmail))).thenReturn(Optional.of(new User(newEmail, "username", "123", "", "")));
+    when(userRepository.findByEmail(eq(newEmail)))
+        .thenReturn(Optional.of(new User(newEmail, "username", "123", "", "")));
     when(userRepository.findByUsername(eq(newUsername))).thenReturn(Optional.empty());
 
     when(userQueryService.findById(eq(user.getId()))).thenReturn(Optional.of(userData));
@@ -134,28 +139,38 @@ public class CurrentUserApiTest extends TestWithCurrentUser {
         .then()
         .statusCode(422)
         .body("errors.email[0]", equalTo("email already exist"));
-
   }
 
-    private HashMap<String, Object> prepareUpdateParam(final String newEmail, final String newBio, final String newUsername) {
+  private HashMap<String, Object> prepareUpdateParam(
-        return new HashMap<String, Object>() {{
+      final String newEmail, final String newBio, final String newUsername) {
-            put("user", new HashMap<String, Object>() {{
+    return new HashMap<String, Object>() {
+      {
+        put(
+            "user",
+            new HashMap<String, Object>() {
+              {
                 put("email", newEmail);
                 put("bio", newBio);
                 put("username", newUsername);
-            }});
+              }
-        }};
+            });
+      }
+    };
   }
 
   @Test
   public void should_get_401_if_not_login() throws Exception {
     given()
         .contentType("application/json")
-            .body(new HashMap<String, Object>() {{
+        .body(
+            new HashMap<String, Object>() {
+              {
                 put("user", new HashMap<String, Object>());
-            }})
+              }
+            })
         .when()
         .put("/user")
-            .then().statusCode(401);
+        .then()
+        .statusCode(401);
   }
 }

src/test/java/io/spring/api/UsersApiTest.java

@@ -1,5 +1,12 @@
 package io.spring.api;
 
+import static io.restassured.module.mockmvc.RestAssuredMockMvc.given;
+import static org.hamcrest.core.IsEqual.equalTo;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
 import io.restassured.module.mockmvc.RestAssuredMockMvc;
 import io.spring.JacksonCustomizations;
 import io.spring.api.security.WebSecurityConfig;
@@ -10,6 +17,9 @@ import io.spring.core.user.User;
 import io.spring.core.user.UserRepository;
 import io.spring.infrastructure.mybatis.readservice.UserReadService;
 import io.spring.infrastructure.service.NaiveEncryptService;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -20,35 +30,24 @@ import org.springframework.context.annotation.Import;
 import org.springframework.test.context.junit4.SpringRunner;
 import org.springframework.test.web.servlet.MockMvc;
 
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Optional;
-
-import static io.restassured.module.mockmvc.RestAssuredMockMvc.given;
-import static org.hamcrest.core.IsEqual.equalTo;
-import static org.mockito.ArgumentMatchers.any;
-import static org.mockito.ArgumentMatchers.eq;
-import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.when;
-
 @RunWith(SpringRunner.class)
 @WebMvcTest(UsersApi.class)
-@Import({WebSecurityConfig.class, UserQueryService.class, NaiveEncryptService.class, JacksonCustomizations.class})
+@Import({
+  WebSecurityConfig.class,
+  UserQueryService.class,
+  NaiveEncryptService.class,
+  JacksonCustomizations.class
+})
 public class UsersApiTest {
-    @Autowired
+  @Autowired private MockMvc mvc;
-    private MockMvc mvc;
 
-    @MockBean
+  @MockBean private UserRepository userRepository;
-    private UserRepository userRepository;
 
-    @MockBean
+  @MockBean private JwtService jwtService;
-    private JwtService jwtService;
 
-    @MockBean
+  @MockBean private UserReadService userReadService;
-    private UserReadService userReadService;
   private String defaultAvatar;
 
-
   @Before
   public void setUp() throws Exception {
     RestAssuredMockMvc.mockMvc(mvc);
@@ -99,6 +98,7 @@ public class UsersApiTest {
         .body(param)
         .when()
         .post("/users")
+        .prettyPeek()
         .then()
         .statusCode(422)
         .body("errors.username[0]", equalTo("can't be empty"));
@@ -116,10 +116,10 @@ public class UsersApiTest {
         .body(param)
         .when()
         .post("/users")
+        .prettyPeek()
         .then()
         .statusCode(422)
         .body("errors.email[0]", equalTo("should be an email"));
-
   }
 
   @Test
@@ -127,9 +127,8 @@ public class UsersApiTest {
     String email = "john@jacob.com";
     String username = "johnjacob";
 
-        when(userRepository.findByUsername(eq(username))).thenReturn(Optional.of(new User(
+    when(userRepository.findByUsername(eq(username)))
-            email, username, "123", "bio", ""
+        .thenReturn(Optional.of(new User(email, username, "123", "bio", "")));
-        )));
     when(userRepository.findByEmail(any())).thenReturn(Optional.empty());
 
     Map<String, Object> param = prepareRegisterParameter(email, username);
@@ -139,6 +138,7 @@ public class UsersApiTest {
         .body(param)
         .when()
         .post("/users")
+        .prettyPeek()
         .then()
         .statusCode(422)
         .body("errors.username[0]", equalTo("duplicated username"));
@@ -149,9 +149,8 @@ public class UsersApiTest {
     String email = "john@jacob.com";
     String username = "johnjacob2";
 
-        when(userRepository.findByEmail(eq(email))).thenReturn(Optional.of(new User(
+    when(userRepository.findByEmail(eq(email)))
-            email, username, "123", "bio", ""
+        .thenReturn(Optional.of(new User(email, username, "123", "bio", "")));
-        )));
 
     when(userRepository.findByUsername(eq(username))).thenReturn(Optional.empty());
 
@@ -167,14 +166,21 @@ public class UsersApiTest {
         .body("errors.email[0]", equalTo("duplicated email"));
   }
 
-    private HashMap<String, Object> prepareRegisterParameter(final String email, final String username) {
+  private HashMap<String, Object> prepareRegisterParameter(
-        return new HashMap<String, Object>() {{
+      final String email, final String username) {
-            put("user", new HashMap<String, Object>() {{
+    return new HashMap<String, Object>() {
+      {
+        put(
+            "user",
+            new HashMap<String, Object>() {
+              {
                 put("email", email);
                 put("password", "johnnyjacob");
                 put("username", username);
-            }});
+              }
-        }};
+            });
+      }
+    };
   }
 
   @Test
@@ -191,12 +197,19 @@ public class UsersApiTest {
     when(userReadService.findById(eq(user.getId()))).thenReturn(userData);
     when(jwtService.toToken(any())).thenReturn("123");
 
-        Map<String, Object> param = new HashMap<String, Object>() {{
+    Map<String, Object> param =
-            put("user", new HashMap<String, Object>() {{
+        new HashMap<String, Object>() {
+          {
+            put(
+                "user",
+                new HashMap<String, Object>() {
+                  {
                     put("email", email);
                     put("password", password);
-            }});
+                  }
-        }};
+                });
+          }
+        };
 
     given()
         .contentType("application/json")
@@ -209,7 +222,8 @@ public class UsersApiTest {
         .body("user.username", equalTo(username))
         .body("user.bio", equalTo(""))
         .body("user.image", equalTo(defaultAvatar))
-            .body("user.token", equalTo("123"));;
+        .body("user.token", equalTo("123"));
+    ;
   }
 
   @Test
@@ -224,20 +238,28 @@ public class UsersApiTest {
     when(userRepository.findByEmail(eq(email))).thenReturn(Optional.of(user));
     when(userReadService.findByUsername(eq(username))).thenReturn(userData);
 
-        Map<String, Object> param = new HashMap<String, Object>() {{
+    Map<String, Object> param =
-            put("user", new HashMap<String, Object>() {{
+        new HashMap<String, Object>() {
+          {
+            put(
+                "user",
+                new HashMap<String, Object>() {
+                  {
                     put("email", email);
                     put("password", "123123");
-            }});
+                  }
-        }};
+                });
+          }
+        };
 
     given()
         .contentType("application/json")
         .body(param)
         .when()
         .post("/users/login")
+        .prettyPeek()
         .then()
         .statusCode(422)
-            .body("errors.password[0]", equalTo("invalid email or password"));
+        .body("message", equalTo("invalid email or password"));
   }
 }