refactor: response에 메시지 제거

StudyCreateResponse에서 message를 제거하고 id만 반환하도록 함
MessageResponse DTO 제거

src/main/java/com/gdgoc/study_group/study/api/StudyController.java

@@ -20,9 +20,10 @@ public StudyController(StudyService studyService, StudyRepository studyRepositor
 
   @PostMapping()
   public ResponseEntity<StudyCreateResponse> createStudy(@RequestBody StudyCreateRequest request) {
-    StudyCreateResponse newStudy = studyService.createStudy(1L, request); // 임시 유저
+    Long createdStudyId = studyService.createStudy(1L, request); // 임시 유저
 
-    return ResponseEntity.status(HttpStatus.CREATED).body(newStudy);
+    return ResponseEntity.status(HttpStatus.CREATED)
+            .body(StudyCreateResponse.builder().id(createdStudyId).build());
   }
 
   @GetMapping()
@@ -37,8 +38,7 @@ public ResponseEntity<?> getStudyDetail(@PathVariable("studyId") Long studyId) {
     StudyDetailResponse studyDetail = studyService.getStudyDetail(studyId);
 
     if (studyDetail == null) {
-      return ResponseEntity.status(HttpStatus.NOT_FOUND)
-          .body(MessageResponse.builder().message("해당하는 스터디가 없습니다.").build());
+      return ResponseEntity.status(HttpStatus.NOT_FOUND).body("해당하는 스터디가 없습니다.");
     }
 
     return ResponseEntity.status(HttpStatus.OK).body(studyDetail);
@@ -47,26 +47,26 @@ public ResponseEntity<?> getStudyDetail(@PathVariable("studyId") Long studyId) {
   @PatchMapping("/{studyId}")
   public ResponseEntity<?> updateStudy(
       @PathVariable("studyId") Long studyId, @RequestBody StudyCreateRequest updateRequest) {
+
     Long updatedStudyId = studyService.updateStudy(studyId, updateRequest);
+
     if (updatedStudyId == null) {
-      return ResponseEntity.status(HttpStatus.NOT_FOUND)
-          .body(MessageResponse.builder().message("해당하는 스터디가 없습니다").build());
+      return ResponseEntity.status(HttpStatus.NOT_FOUND).build();
     }
+
     return ResponseEntity.status(HttpStatus.OK)
-        .body(StudyCreateResponse.builder().message("스터디가 수정되었습니다.").id(updatedStudyId).build());
+        .body(StudyCreateResponse.builder().id(updatedStudyId).build());
   }
 
   @DeleteMapping("/{studyId}")
-  public ResponseEntity<MessageResponse> deleteStudy(@PathVariable("studyId") Long studyId) {
+  public ResponseEntity<String> deleteStudy(@PathVariable("studyId") Long studyId) {
 
     boolean isStudyExist = studyService.deleteStudy(studyId);
 
     if (isStudyExist) {
-      return ResponseEntity.status(HttpStatus.NO_CONTENT)
-          .body(MessageResponse.builder().message("스터디가 삭제되었습니다.").build());
+      return ResponseEntity.status(HttpStatus.NO_CONTENT).body("스터디가 삭제되었습니다.");
     }
 
-    return ResponseEntity.status(HttpStatus.NOT_FOUND)
-        .body(MessageResponse.builder().message("해당하는 스터디가 없습니다.").build());
+    return ResponseEntity.status(HttpStatus.NOT_FOUND).body("해당하는 스터디가 없습니다.");
   }
 }

src/main/java/com/gdgoc/study_group/study/application/StudyService.java

@@ -52,7 +52,7 @@ private Day createDay(DayDTO dayDTO, Study study) {
    * @param createRequest 스터디 생성 DTO
    * @return ResponseDTO 반환
    */
-  public StudyCreateResponse createStudy(Long userId, StudyCreateRequest createRequest) {
+  public Long createStudy(Long userId, StudyCreateRequest createRequest) {
 
     Study study =
         Study.builder()
@@ -87,7 +87,7 @@ public StudyCreateResponse createStudy(Long userId, StudyCreateRequest createReq
 
     studyRepository.save(study);
 
-    return StudyCreateResponse.builder().message("스터디가 생성되었습니다").id(study.getId()).build();
+    return study.getId();
   }
 
   /**

src/main/java/com/gdgoc/study_group/study/dto/StudyCreateResponse.java

@@ -6,6 +6,5 @@
 @Getter
 @Builder
 public class StudyCreateResponse {
-  private String message;
   private Long id;
 }