add @transactional annotations to service methods for improved transaction management

Author: while1618

backend/spring-boot/src/main/java/org/bugzkit/api/admin/service/impl/UserServiceImpl.java

@@ -91,6 +91,7 @@ public PageableDTO<UserDTO> findAll(Pageable pageable) {
   }
 
   @Override
+  @Transactional(readOnly = true)
   public UserDTO findById(Long id) {
     return userRepository
         .findWithRolesById(id)
@@ -235,6 +236,7 @@ private void setRoles(User user, Set<RoleName> roleNames) {
   }
 
   @Override
+  @Transactional
   public void delete(Long id) {
     deleteAuthTokens(id);
     userRepository.deleteById(id);

backend/spring-boot/src/main/java/org/bugzkit/api/auth/oauth2/OAuth2UserService.java

@@ -15,6 +15,7 @@
 import org.springframework.security.oauth2.core.OAuth2AuthenticationException;
 import org.springframework.security.oauth2.core.user.OAuth2User;
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
 
 @Slf4j
 @Service
@@ -28,6 +29,7 @@ public OAuth2UserService(UserRepository userRepository, RoleRepository roleRepos
   }
 
   @Override
+  @Transactional
   public OAuth2User loadUser(OAuth2UserRequest userRequest) throws OAuth2AuthenticationException {
     MDC.put("REQUEST_ID", UUID.randomUUID().toString());
     final var oAuthUser = super.loadUser(userRequest);

backend/spring-boot/src/main/java/org/bugzkit/api/auth/service/impl/AuthServiceImpl.java

@@ -202,6 +202,7 @@ public void sendVerificationMail(VerificationEmailRequest request) {
   }
 
   @Override
+  @Transactional
   public void verifyEmail(VerifyEmailRequest verifyEmailRequest) {
     final var userId = verificationTokenService.checkAndConsume(verifyEmailRequest.token());
     final var user =

backend/spring-boot/src/main/java/org/bugzkit/api/auth/service/impl/DeviceServiceImpl.java

@@ -39,6 +39,7 @@ public DeviceServiceImpl(
   }
 
   @Override
+  @Transactional(readOnly = true)
   public List<DeviceDTO> findAll(String currentDeviceId) {
     final var userId = AuthUtil.findSignedInUser().getId();
     return deviceRepository.findAllByUserId(userId).stream()

backend/spring-boot/src/main/java/org/bugzkit/api/user/service/impl/RoleServiceImpl.java

@@ -7,6 +7,7 @@
 import org.bugzkit.api.user.service.RoleService;
 import org.springframework.security.access.prepost.PreAuthorize;
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
 
 @Service
 @PreAuthorize("hasAuthority('ADMIN')")
@@ -18,6 +19,7 @@ public RoleServiceImpl(RoleRepository roleRepository) {
   }
 
   @Override
+  @Transactional(readOnly = true)
   public List<RoleDTO> findAll() {
     return roleRepository.findAll().stream().map(UserMapper.INSTANCE::roleToRoleDTO).toList();
   }

backend/spring-boot/src/main/java/org/bugzkit/api/user/service/impl/UserServiceImpl.java

@@ -35,6 +35,7 @@ public PageableDTO<UserDTO> findAll(Pageable pageable) {
   }
 
   @Override
+  @Transactional(readOnly = true)
   public UserDTO findById(Long id) {
     return userRepository
         .findById(id)
@@ -47,6 +48,7 @@ public UserDTO findById(Long id) {
   }
 
   @Override
+  @Transactional(readOnly = true)
   public UserDTO findByUsername(String username) {
     return userRepository
         .findByUsername(username)
@@ -59,13 +61,15 @@ public UserDTO findByUsername(String username) {
   }
 
   @Override
+  @Transactional(readOnly = true)
   public AvailabilityDTO usernameAvailability(
       UsernameAvailabilityRequest usernameAvailabilityRequest) {
     final var available = !userRepository.existsByUsername(usernameAvailabilityRequest.username());
     return new AvailabilityDTO(available);
   }
 
   @Override
+  @Transactional(readOnly = true)
   public AvailabilityDTO emailAvailability(EmailAvailabilityRequest emailAvailabilityRequest) {
     final var available = !userRepository.existsByEmail(emailAvailabilityRequest.email());
     return new AvailabilityDTO(available);