feat: 보관한 쪽지 리스트 조회 구현

src/main/java/com/cake/pop/domain/letter/controller/LetterController.java

@@ -4,8 +4,10 @@
 import com.cake.pop.domain.letter.dto.request.CreateStorageRequest;
 import com.cake.pop.domain.letter.dto.response.GetLetterResponse;
 import com.cake.pop.domain.letter.dto.response.GetLettersResponse;
+import com.cake.pop.domain.letter.dto.response.SimpleLetterDto;
 import com.cake.pop.domain.letter.service.LetterService;
 import jakarta.validation.Valid;
+import java.util.List;
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.GetMapping;
@@ -42,11 +44,17 @@ public ResponseEntity<GetLetterResponse> getLetter(@PathVariable("letterId") Lon
     }
 
     @PostMapping("/storage")
-    public ResponseEntity<Void> createStorage(@RequestBody @Valid CreateStorageRequest request){
+    public ResponseEntity<Void> createStorage(@RequestBody @Valid CreateStorageRequest request) {
         Long userId = 1L;
         letterService.createStorage(userId, request);
         return ResponseEntity.ok().build();
     }
 
+    @GetMapping("/storages")
+    public ResponseEntity<List<SimpleLetterDto>> getStorages() {
+        Long userId = 1L;
+        List<SimpleLetterDto> response = letterService.getStorages(userId);
+        return ResponseEntity.ok(response);
+    }
 
 }

src/main/java/com/cake/pop/domain/letter/repository/StorageRepository.java

@@ -1,9 +1,15 @@
 package com.cake.pop.domain.letter.repository;
 
 import com.cake.pop.entity.Storage;
+import com.cake.pop.entity.User;
+import java.util.List;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
 import org.springframework.stereotype.Repository;
 
 @Repository
 public interface StorageRepository extends JpaRepository<Storage, Long> {
+
+    @Query("SELECT s FROM Storage s JOIN FETCH s.letter WHERE s.user = :user")
+    List<Storage> findByUser(User user);
 }

src/main/java/com/cake/pop/domain/letter/service/LetterService.java

@@ -70,4 +70,20 @@ public void createStorage(Long userId, CreateStorageRequest request){
 
         storageRepository.save(storage);
     }
+
+    public List<SimpleLetterDto> getStorages(Long userId){
+        User findUser = userRepository.getById(userId);
+        List<Storage> storages = storageRepository.findByUser(findUser);
+
+        return storages.stream()
+                .map(storage -> {
+                    Letter letter = storage.getLetter();
+                    return new SimpleLetterDto(
+                            letter.getId(),
+                            letter.getContent(),
+                            letter.getCreatedAt().toLocalDate() // LocalDateTime → LocalDate
+                    );
+                })
+                .toList();
+    }
 }