feat: monthly Diary Lookup API

src/main/java/com/hadam/hadam/controller/DiaryController.java

@@ -36,4 +36,10 @@ public ResponseEntity<BaseResponse<?>> updateIsLiked(@PathVariable Long diaryId)
                 .body(BaseResponse.of(SuccessCode.OK));
     }
 
+    @GetMapping("/monthly")
+    public ResponseEntity<BaseResponse<?>> getMonthlyDiary(@RequestParam Long memberId, @RequestParam int year, @RequestParam int month){
+        return ResponseEntity.status(HttpStatus.OK)
+                .body(BaseResponse.of(SuccessCode.OK, diaryService.getMonthlyDiary(memberId, year, month)));
+    }
+
 }

src/main/java/com/hadam/hadam/domain/Diary.java

@@ -6,6 +6,8 @@
 import lombok.Getter;
 import lombok.NoArgsConstructor;
 
+import java.time.LocalDateTime;
+
 @Entity
 @Getter
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
@@ -16,6 +18,8 @@ public class Diary extends BaseTimeEntity {
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
+    private LocalDateTime date;
+
     @Column(columnDefinition = "LONGTEXT")
     private String img;
 

src/main/java/com/hadam/hadam/dto/response/MonthlyRepresentRes.java

@@ -0,0 +1,8 @@
+package com.hadam.hadam.dto.response;
+
+public record MonthlyRepresentRes(
+        Long id,
+        String img,
+        String yearMonth
+) {
+}

src/main/java/com/hadam/hadam/global/error/exception/ErrorCode.java

@@ -30,6 +30,7 @@ public enum ErrorCode {
      * 404 Not Found
      */
     ENTITY_NOT_FOUND(HttpStatus.NOT_FOUND, "엔티티를 찾을 수 없습니다."),
+    MONTHLY_NOT_FOUND(HttpStatus.NOT_FOUND, "해당하는 달의 일기가 없습니다."),
 
     /**
      * 405 Method Not Allowed

src/main/java/com/hadam/hadam/repository/DiaryRepository.java

@@ -4,11 +4,23 @@
 import com.hadam.hadam.global.error.exception.EntityNotFoundException;
 import com.hadam.hadam.global.error.exception.ErrorCode;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+
+import java.util.List;
 
 public interface DiaryRepository extends JpaRepository<Diary, Long> {
 
     default Diary findByIdOrThrow(Long diaryId){
         return findById(diaryId)
                 .orElseThrow(()-> new EntityNotFoundException(ErrorCode.ENTITY_NOT_FOUND));
     }
+
+    @Query("SELECT d FROM Diary d " +
+            "WHERE d.member.id = :memberId " +
+            "AND YEAR(d.date) = :year AND MONTH(d.date) = :month")
+    List<Diary> findDiariesByMemberIdAndYearMonth(@Param("memberId") Long memberId,
+                                                  @Param("year") int year,
+                                                  @Param("month") int month);
+
 }

src/main/java/com/hadam/hadam/service/DiaryService.java

@@ -4,27 +4,36 @@
 import com.hadam.hadam.domain.DiaryInfo;
 import com.hadam.hadam.domain.Member;
 import com.hadam.hadam.dto.request.UpdateDiaryReq;
+import com.hadam.hadam.dto.response.MonthlyRepresentRes;
+import com.hadam.hadam.global.error.exception.EntityNotFoundException;
+import com.hadam.hadam.global.error.exception.ErrorCode;
 import com.hadam.hadam.repository.DiaryInfoRepository;
 import com.hadam.hadam.repository.DiaryRepository;
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.YearMonth;
+import java.time.format.DateTimeFormatter;
+import java.util.List;
+import java.util.Random;
+
 @Service
 @RequiredArgsConstructor
+@Transactional
 public class DiaryService {
 
     private final DiaryRepository diaryRepository;
     private final DiaryInfoRepository diaryInfoRepository;
 
-    @Transactional
     public Long updateDiary(Long diaryId, UpdateDiaryReq updateDiaryReq){
         Diary diary = diaryRepository.findByIdOrThrow(diaryId);
         diary.setDiaryContent(updateDiaryReq.content());
         return diaryId;
     }
 
-    @Transactional
     public void deleteDiary(Long diaryId){
         Diary diary = diaryRepository.findByIdOrThrow(diaryId);
         diaryRepository.delete(diary);
@@ -36,13 +45,39 @@ public DiaryInfo getDiaryInfoByDiary(Diary diary) {
         return diaryInfoRepository.findDiaryInfoByDiary(diary);
     }
 
-    @Transactional
     public void updateIsLiked(Long diaryId){
         Diary diary = diaryRepository.findByIdOrThrow(diaryId);
         diary.setIsLiked(!diary.isLiked());
         diaryRepository.save(diary);
     }
 
+    @Transactional(readOnly = true)
+    public MonthlyRepresentRes getMonthlyDiary(Long memberId, int year, int month){
+        List<Diary> diaries = diaryRepository.findDiariesByMemberIdAndYearMonth(
+                memberId,
+                year,
+                month
+        );
+
+        if (diaries.isEmpty()) {
+            throw new EntityNotFoundException(ErrorCode.MONTHLY_NOT_FOUND);
+        }
+
+        // 랜덤으로 선택
+        Random random = new Random();
+        Diary randomDiary = diaries.get(random.nextInt(diaries.size()));
+
+        return new MonthlyRepresentRes(
+                randomDiary.getId(),
+                randomDiary.getImg(),
+                formatYearMonth(year, month)
+        );
+    }
+
+    public static String formatYearMonth(int year, int month) {
+        return year + " " + month + "월";
+    }
+
 
 
 }