custom exception handling mechanism is added

app/backend/src/main/java/com/app/gamereview/controller/CustomExceptionHandler.java

@@ -0,0 +1,23 @@
+package com.app.gamereview.controller;
+
+
+import com.app.gamereview.exception.BadRequestException;
+import com.app.gamereview.exception.ResourceNotFoundException;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+
+
+@ControllerAdvice
+public class CustomExceptionHandler {
+    @ExceptionHandler(ResourceNotFoundException.class)
+    public ResponseEntity<Object> handleResourceNotFoundException(ResourceNotFoundException ex) {
+        return ResponseEntity.status(HttpStatus.NOT_FOUND).body(ex.getMessage());
+    }
+
+    @ExceptionHandler(BadRequestException.class)
+    public ResponseEntity<Object> handleBadRequestException(BadRequestException ex) {
+        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(ex.getMessage());
+    }
+}

app/backend/src/main/java/com/app/gamereview/exception/BadRequestException.java

@@ -0,0 +1,7 @@
+package com.app.gamereview.exception;
+
+public class BadRequestException extends RuntimeException {
+    public BadRequestException(String message) {
+        super(message);
+    }
+}

app/backend/src/main/java/com/app/gamereview/exception/ResourceNotFoundException.java

@@ -0,0 +1,7 @@
+package com.app.gamereview.exception;
+
+public class ResourceNotFoundException extends RuntimeException {
+    public ResourceNotFoundException(String message) {
+        super(message);
+    }
+}

app/backend/src/main/java/com/app/gamereview/service/AuthService.java

@@ -3,6 +3,8 @@
 import com.app.gamereview.dto.request.*;
 import com.app.gamereview.dto.response.LoginUserResponseDto;
 import com.app.gamereview.dto.response.UserResponseDto;
+import com.app.gamereview.exception.BadRequestException;
+import com.app.gamereview.exception.ResourceNotFoundException;
 import com.app.gamereview.model.User;
 import com.app.gamereview.repository.UserRepository;
 import org.modelmapper.ModelMapper;
@@ -33,8 +35,7 @@ public User registerUser(RegisterUserRequestDto registerUserRequestDto) {
 		Optional<User> sameEmail = userRepository.findByEmailAndIsDeletedFalse(registerUserRequestDto.getEmail());
 
 		if (sameUsername.isPresent() || sameEmail.isPresent()) {
-			// TODO : will add exception handling mechanism and custom exceptions
-			return null;
+			throw new BadRequestException("User with the same information already exists");
 		}
 		User userToCreate = modelMapper.map(registerUserRequestDto, User.class);
 		userToCreate.setIsDeleted(false);

app/backend/src/main/java/com/app/gamereview/service/GameService.java

@@ -10,6 +10,7 @@
 import com.app.gamereview.dto.response.UserResponseDto;
 import com.app.gamereview.dto.response.tag.AddGameTagResponseDto;
 import com.app.gamereview.dto.response.tag.GetAllTagsOfGameResponseDto;
+import com.app.gamereview.exception.ResourceNotFoundException;
 import com.app.gamereview.model.Tag;
 import com.app.gamereview.model.User;
 import com.app.gamereview.repository.TagRepository;
@@ -94,8 +95,7 @@ public GetAllTagsOfGameResponseDto getGameTags(String gameId){
 		Optional<Game> findGame = gameRepository.findById(gameId);
 
 		if(findGame.isEmpty() || findGame.get().getIsDeleted()){
-			// TODO exception
-			return null;
+			throw new ResourceNotFoundException("Game does not exist");
 		}
 
 		Game game = findGame.get();
@@ -120,13 +120,11 @@ public AddGameTagResponseDto addGameTag(AddGameTagRequestDto request){
 		Optional<Tag> findTag = tagRepository.findById(request.getTagId());
 
 		if(findGame.isEmpty() || findGame.get().getIsDeleted()){
-			// TODO exception
-			return null;
+			throw new ResourceNotFoundException("Game does not exist");
 		}
 
 		if(findTag.isEmpty() || findTag.get().getIsDeleted()){
-			// TODO exception
-			return null;
+			throw new ResourceNotFoundException("Tag does not exist");
 		}
 
 		Game game = findGame.get();

app/backend/src/main/java/com/app/gamereview/service/TagService.java

@@ -3,6 +3,8 @@
 import com.app.gamereview.dto.request.tag.CreateTagRequestDto;
 import com.app.gamereview.dto.request.tag.GetAllTagsFilterRequestDto;
 import com.app.gamereview.dto.request.tag.UpdateTagRequestDto;
+import com.app.gamereview.exception.BadRequestException;
+import com.app.gamereview.exception.ResourceNotFoundException;
 import com.app.gamereview.model.Tag;
 import com.app.gamereview.model.User;
 import com.app.gamereview.repository.TagRepository;
@@ -68,8 +70,7 @@ public Tag createTag(CreateTagRequestDto request){
 				.findByNameAndIsDeletedFalse(request.getName());
 
 		if (sameName.isPresent()) {
-			// TODO : will add exception handling mechanism and custom exceptions
-			return null;
+			throw new BadRequestException("Tag with the same name already exist");
 		}
 		Tag tagToCreate = modelMapper.map(request, Tag.class);
 		tagToCreate.setIsDeleted(false);
@@ -81,8 +82,7 @@ public Tag updateTag(String id, UpdateTagRequestDto request){
 		Optional<Tag> tag = tagRepository.findById(id);
 
 		if (tag.isEmpty() || tag.get().getIsDeleted()){
-			// TODO : will add exception handling mechanism and custom exceptions
-			return null;
+			throw new ResourceNotFoundException("Tag desired to be updated does not exist");
 		}
 
 		Tag tagToUpdate = modelMapper.map(request, Tag.class);