#21-append 중복 방지 로직 추가

src/main/java/flab/quing/waiting/DuplicateWaitingException.java

@@ -0,0 +1,4 @@
+package flab.quing.waiting;
+
+public class DuplicateWaitingException extends RuntimeException {
+}

src/main/java/flab/quing/waiting/QuingServiceImpl.java

@@ -13,6 +13,7 @@
 import org.springframework.transaction.annotation.Transactional;
 
 import java.util.List;
+import java.util.Optional;
 import java.util.stream.Collectors;
 
 @RequiredArgsConstructor
@@ -29,8 +30,12 @@ public WaitingResponse append(WaitingRequest waitingRequest) {
         User user = userRepository.findById(waitingRequest.getUserId()).orElseThrow(NoSuchUserException::new);
         Store store = storeRepository.findById(waitingRequest.getStoreId()).orElseThrow(NoSuchStoreException::new);
         Waiting waiting = Waiting.of(user, store);
-        Waiting save = waitingRepository.save(waiting);
 
+        Optional<Waiting> exist = waitingRepository.findByUserIdAndWaitingQueueStatusIs(user.getId(), WaitingQueueStatus.WAITING);
+        if(exist.isPresent()) {
+            throw new DuplicateWaitingException();
+        }
+        Waiting save = waitingRepository.save(waiting);
         return save.toResponse();
     }
 

src/main/java/flab/quing/waiting/WaitingRepository.java

@@ -3,8 +3,11 @@
 import org.springframework.data.jpa.repository.JpaRepository;
 
 import java.util.List;
+import java.util.Optional;
 
 public interface WaitingRepository extends JpaRepository<Waiting, Long> {
 
+    Optional<Waiting> findByUserIdAndWaitingQueueStatusIs(long userId, WaitingQueueStatus waitingQueueStatus);
+
     List<Waiting> findAllByStoreIdAndWaitingQueueStatusIs(long storeId, WaitingQueueStatus waitingQueueStatus);
 }