[DP-307/308] 커뮤니티 게시글/답변 삭제, 중복 제출, 목록 필드 누락, 타임스탬프 불일치 수정

src/main/java/com/devpick/domain/community/dto/PostSummaryResponse.java

@@ -16,9 +16,20 @@ public record PostSummaryResponse(
         String authorNickname,
         Job authorJob,
         String authorProfileImage,
-        Instant createdAt
+        Instant createdAt,
+        long answerCount,
+        String contentPreview,
+        String topAnswerPreview
 ) {
-    public static PostSummaryResponse of(Post post) {
+    private static final int CONTENT_PREVIEW_LENGTH = 150;
+    private static final int ANSWER_PREVIEW_LENGTH = 100;
+
+    public static PostSummaryResponse of(Post post, long answerCount, String topAnswerPreview) {
+        String content = post.getContent();
+        String contentPreview = content != null && content.length() > CONTENT_PREVIEW_LENGTH
+                ? content.substring(0, CONTENT_PREVIEW_LENGTH) + "..."
+                : content;
+
         return new PostSummaryResponse(
                 post.getId(),
                 post.getTitle(),
@@ -27,7 +38,17 @@ public static PostSummaryResponse of(Post post) {
                 post.getUser().getNickname(),
                 post.getUser().getJob(),
                 post.getUser().getProfileImage(),
-                post.getCreatedAt() != null ? post.getCreatedAt().toInstant(ZoneOffset.UTC) : null
+                post.getCreatedAt() != null ? post.getCreatedAt().toInstant(ZoneOffset.UTC) : null,
+                answerCount,
+                contentPreview,
+                topAnswerPreview
         );
     }
+
+    public static String truncateAnswerPreview(String content) {
+        if (content == null) return null;
+        return content.length() > ANSWER_PREVIEW_LENGTH
+                ? content.substring(0, ANSWER_PREVIEW_LENGTH) + "..."
+                : content;
+    }
 }

src/main/java/com/devpick/domain/community/repository/AiAnswerRepository.java

@@ -2,11 +2,18 @@
 
 import com.devpick.domain.community.entity.AiAnswer;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 
 import java.util.Optional;
 import java.util.UUID;
 
 public interface AiAnswerRepository extends JpaRepository<AiAnswer, UUID> {
 
     Optional<AiAnswer> findByPost_Id(UUID postId);
+
+    @Modifying
+    @Query("DELETE FROM AiAnswer a WHERE a.post.id = :postId")
+    void deleteByPostId(@Param("postId") UUID postId);
 }

src/main/java/com/devpick/domain/community/repository/AiQuestionRepository.java

@@ -2,11 +2,18 @@
 
 import com.devpick.domain.community.entity.AiQuestion;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 
 import java.util.Optional;
 import java.util.UUID;
 
 public interface AiQuestionRepository extends JpaRepository<AiQuestion, UUID> {
 
     Optional<AiQuestion> findByPost_Id(UUID postId);
+
+    @Modifying
+    @Query("DELETE FROM AiQuestion q WHERE q.post.id = :postId")
+    void deleteByPostId(@Param("postId") UUID postId);
 }

src/main/java/com/devpick/domain/community/repository/AnswerLikeRepository.java

@@ -2,6 +2,9 @@
 
 import com.devpick.domain.community.entity.AnswerLike;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 
 import java.util.Optional;
 import java.util.UUID;
@@ -13,4 +16,12 @@ public interface AnswerLikeRepository extends JpaRepository<AnswerLike, UUID> {
     Optional<AnswerLike> findByAnswer_IdAndUser_Id(UUID answerId, UUID userId);
 
     long countByAnswer_Id(UUID answerId);
+
+    @Modifying
+    @Query("DELETE FROM AnswerLike al WHERE al.answer.id = :answerId")
+    void deleteByAnswerId(@Param("answerId") UUID answerId);
+
+    @Modifying
+    @Query("DELETE FROM AnswerLike al WHERE al.answer.id IN (SELECT a.id FROM Answer a WHERE a.post.id = :postId)")
+    void deleteByPostId(@Param("postId") UUID postId);
 }

src/main/java/com/devpick/domain/community/repository/AnswerRepository.java

@@ -4,6 +4,7 @@
 import jakarta.persistence.LockModeType;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Lock;
+import org.springframework.data.jpa.repository.Modifying;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;
 
@@ -25,4 +26,11 @@ public interface AnswerRepository extends JpaRepository<Answer, UUID> {
 
     @Query("SELECT a FROM Answer a JOIN FETCH a.post WHERE a.user.id = :userId ORDER BY a.createdAt DESC")
     List<Answer> findByUserIdWithPost(@Param("userId") UUID userId);
+
+    @Query("SELECT a FROM Answer a JOIN FETCH a.post WHERE a.post.id IN :postIds ORDER BY a.post.id, a.createdAt ASC")
+    List<Answer> findByPostIdsOrderByCreatedAtAsc(@Param("postIds") List<UUID> postIds);
+
+    @Modifying
+    @Query("DELETE FROM Answer a WHERE a.post.id = :postId")
+    void deleteByPostId(@Param("postId") UUID postId);
 }

src/main/java/com/devpick/domain/community/repository/CommentRepository.java

@@ -2,11 +2,22 @@
 
 import com.devpick.domain.community.entity.Comment;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 
 import java.util.List;
 import java.util.UUID;
 
 public interface CommentRepository extends JpaRepository<Comment, UUID> {
 
     List<Comment> findByAnswer_IdOrderByCreatedAtAsc(UUID answerId);
+
+    @Modifying
+    @Query("DELETE FROM Comment c WHERE c.answer.id = :answerId")
+    void deleteByAnswerId(@Param("answerId") UUID answerId);
+
+    @Modifying
+    @Query("DELETE FROM Comment c WHERE c.answer.id IN (SELECT a.id FROM Answer a WHERE a.post.id = :postId)")
+    void deleteByPostId(@Param("postId") UUID postId);
 }

src/main/java/com/devpick/domain/community/repository/PostLikeRepository.java

@@ -2,6 +2,9 @@
 
 import com.devpick.domain.community.entity.PostLike;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 
 import java.util.Optional;
 import java.util.UUID;
@@ -13,4 +16,8 @@ public interface PostLikeRepository extends JpaRepository<PostLike, UUID> {
     Optional<PostLike> findByPost_IdAndUser_Id(UUID postId, UUID userId);
 
     long countByPost_Id(UUID postId);
+
+    @Modifying
+    @Query("DELETE FROM PostLike pl WHERE pl.post.id = :postId")
+    void deleteByPostId(@Param("postId") UUID postId);
 }

src/main/java/com/devpick/domain/community/repository/PostRepository.java

@@ -7,6 +7,7 @@
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;
 
+import java.time.LocalDateTime;
 import java.util.List;
 import java.util.UUID;
 
@@ -22,4 +23,6 @@ OR LOWER(p.content) LIKE LOWER(CONCAT('%', :q, '%'))
     Page<Post> searchByTitleOrContentContaining(@Param("q") String q, Pageable pageable);
 
     List<Post> findByUser_IdOrderByCreatedAtDesc(UUID userId);
+
+    boolean existsByUser_IdAndTitleAndCreatedAtAfter(UUID userId, String title, LocalDateTime after);
 }

src/main/java/com/devpick/domain/community/service/AnswerService.java

@@ -8,6 +8,7 @@
 import com.devpick.domain.community.entity.Answer;
 import com.devpick.domain.community.entity.Comment;
 import com.devpick.domain.community.entity.Post;
+import com.devpick.domain.community.repository.AnswerLikeRepository;
 import com.devpick.domain.community.repository.AnswerRepository;
 import com.devpick.domain.community.repository.CommentRepository;
 import com.devpick.domain.community.repository.PostRepository;
@@ -36,6 +37,7 @@ public class AnswerService {
     private final HistoryRepository historyRepository;
     private final PointService pointService;
     private final CommentRepository commentRepository;
+    private final AnswerLikeRepository answerLikeRepository;
 
     @Transactional(readOnly = true)
     public AnswerListResponse getAnswers(UUID postId) {
@@ -105,6 +107,10 @@ public void deleteAnswer(UUID userId, UUID postId, UUID answerId) {
             throw new DevpickException(ErrorCode.COMMUNITY_UNAUTHORIZED_ANSWER_ACTION);
         }
 
+        // 자식 레코드 순서대로 삭제 (FK 제약조건 준수)
+        commentRepository.deleteByAnswerId(answerId);
+        answerLikeRepository.deleteByAnswerId(answerId);
+        historyRepository.deleteByAnswerId(answerId);
         answerRepository.delete(answer);
     }
 

src/main/java/com/devpick/domain/community/service/PostService.java

@@ -6,7 +6,12 @@
 import com.devpick.domain.community.dto.PostSummaryResponse;
 import com.devpick.domain.community.dto.PostUpdateRequest;
 import com.devpick.domain.community.entity.Post;
+import com.devpick.domain.community.repository.AiAnswerRepository;
+import com.devpick.domain.community.repository.AiQuestionRepository;
+import com.devpick.domain.community.repository.AnswerLikeRepository;
 import com.devpick.domain.community.repository.AnswerRepository;
+import com.devpick.domain.community.repository.CommentRepository;
+import com.devpick.domain.community.repository.PostLikeRepository;
 import com.devpick.domain.community.repository.PostRepository;
 import com.devpick.domain.point.entity.PointAction;
 import com.devpick.domain.point.service.PointService;
@@ -25,8 +30,11 @@
 import org.springframework.util.StringUtils;
 import org.springframework.transaction.annotation.Transactional;
 
+import java.time.LocalDateTime;
 import java.util.List;
+import java.util.Map;
 import java.util.UUID;
+import java.util.stream.Collectors;
 
 @Service
 @RequiredArgsConstructor
@@ -37,12 +45,22 @@ public class PostService {
     private final UserRepository userRepository;
     private final HistoryRepository historyRepository;
     private final PointService pointService;
+    private final PostLikeRepository postLikeRepository;
+    private final AiAnswerRepository aiAnswerRepository;
+    private final AiQuestionRepository aiQuestionRepository;
+    private final CommentRepository commentRepository;
+    private final AnswerLikeRepository answerLikeRepository;
 
     @Transactional
     public PostDetailResponse createPost(UUID userId, PostCreateRequest request) {
         User user = userRepository.findByIdAndIsActiveTrue(userId)
                 .orElseThrow(() -> new DevpickException(ErrorCode.USER_NOT_FOUND));
 
+        // 10초 이내 동일 제목 중복 제출 방지
+        if (postRepository.existsByUser_IdAndTitleAndCreatedAtAfter(userId, request.title(), LocalDateTime.now().minusSeconds(10))) {
+            throw new DevpickException(ErrorCode.COMMUNITY_DUPLICATE_POST);
+        }
+
         Post post = Post.builder()
                 .user(user)
                 .title(request.title())
@@ -76,9 +94,39 @@ public PostListResponse getPosts(Pageable pageable, String query) {
         } else {
             page = postRepository.findAllByOrderByCreatedAtDesc(pageable);
         }
-        List<PostSummaryResponse> posts = page.getContent().stream()
-                .map(PostSummaryResponse::of)
+
+        List<Post> postList = page.getContent();
+        if (postList.isEmpty()) {
+            return new PostListResponse(List.of(), page.getNumber(), page.getSize(),
+                    page.getTotalElements(), page.getTotalPages());
+        }
+
+        List<UUID> postIds = postList.stream().map(Post::getId).toList();
+
+        // 답변 수 배치 조회
+        Map<UUID, Long> answerCountMap = answerRepository.countByPostIds(postIds).stream()
+                .collect(Collectors.toMap(
+                        row -> (UUID) row[0],
+                        row -> (Long) row[1]
+                ));
+
+        // 첫 번째 답변 미리보기 배치 조회 (postId → truncated content)
+        Map<UUID, String> topAnswerPreviews = answerRepository.findByPostIdsOrderByCreatedAtAsc(postIds)
+                .stream()
+                .collect(Collectors.toMap(
+                        a -> a.getPost().getId(),
+                        a -> PostSummaryResponse.truncateAnswerPreview(a.getContent()),
+                        (first, second) -> first  // 가장 오래된 답변 유지
+                ));
+
+        List<PostSummaryResponse> posts = postList.stream()
+                .map(post -> PostSummaryResponse.of(
+                        post,
+                        answerCountMap.getOrDefault(post.getId(), 0L),
+                        topAnswerPreviews.get(post.getId())
+                ))
                 .toList();
+
         return new PostListResponse(posts, page.getNumber(), page.getSize(),
                 page.getTotalElements(), page.getTotalPages());
     }
@@ -114,6 +162,15 @@ public void deletePost(UUID userId, UUID postId) {
             throw new DevpickException(ErrorCode.COMMUNITY_UNAUTHORIZED_POST_ACTION);
         }
 
+        // 자식 레코드 순서대로 삭제 (FK 제약조건 준수)
+        commentRepository.deleteByPostId(postId);
+        answerLikeRepository.deleteByPostId(postId);
+        historyRepository.deleteByAnswerPostId(postId);
+        answerRepository.deleteByPostId(postId);
+        postLikeRepository.deleteByPostId(postId);
+        aiAnswerRepository.deleteByPostId(postId);
+        aiQuestionRepository.deleteByPostId(postId);
+        historyRepository.deleteByPostId(postId);
         postRepository.delete(post);
     }
 }

src/main/java/com/devpick/domain/report/repository/HistoryRepository.java

@@ -4,6 +4,7 @@
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Modifying;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;
 
@@ -99,4 +100,16 @@ Page<UUID> findHistoryIdsByDateRangeExcludingContentLiked(
            "WHERE h.id IN :ids " +
            "ORDER BY h.createdAt DESC")
     List<History> findHistoriesWithAssociationsByIds(@Param("ids") List<UUID> ids);
+
+    @Modifying
+    @Query("DELETE FROM History h WHERE h.post.id = :postId")
+    void deleteByPostId(@Param("postId") UUID postId);
+
+    @Modifying
+    @Query("DELETE FROM History h WHERE h.answer.id = :answerId")
+    void deleteByAnswerId(@Param("answerId") UUID answerId);
+
+    @Modifying
+    @Query("DELETE FROM History h WHERE h.answer.id IN (SELECT a.id FROM Answer a WHERE a.post.id = :postId)")
+    void deleteByAnswerPostId(@Param("postId") UUID postId);
 }

src/main/java/com/devpick/global/common/exception/ErrorCode.java

@@ -4,6 +4,7 @@
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.HttpStatus;
 
+
 @Getter
 @RequiredArgsConstructor
 public enum ErrorCode {
@@ -81,6 +82,7 @@ public enum ErrorCode {
     COMMUNITY_POST_NOT_LIKED(HttpStatus.NOT_FOUND, "COMMUNITY_010", "좋아요하지 않은 게시글입니다."),
     COMMUNITY_ANSWER_ALREADY_LIKED(HttpStatus.CONFLICT, "COMMUNITY_011", "이미 좋아요한 답변입니다."),
     COMMUNITY_ANSWER_NOT_LIKED(HttpStatus.NOT_FOUND, "COMMUNITY_012", "좋아요하지 않은 답변입니다."),
+    COMMUNITY_DUPLICATE_POST(HttpStatus.CONFLICT, "COMMUNITY_013", "잠시 후 다시 시도해 주세요."),
 
     // Report
     REPORT_NOT_FOUND(HttpStatus.NOT_FOUND, "REPORT_001", "주간 리포트를 찾을 수 없습니다."),

src/main/java/com/devpick/global/entity/BaseTimeEntity.java

@@ -33,8 +33,9 @@ public abstract class BaseTimeEntity {
 
     @PrePersist
     protected void onCreate() {
-        this.createdAt = LocalDateTime.now();
-        this.updatedAt = LocalDateTime.now();
+        LocalDateTime now = LocalDateTime.now();
+        this.createdAt = now;
+        this.updatedAt = now;
     }
 
     @PreUpdate

src/test/java/com/devpick/domain/community/controller/PostControllerTest.java

@@ -124,7 +124,7 @@ void createPost_validationFails_returns400() throws Exception {
     @DisplayName("GET /posts - 목록 조회 성공 시 200과 목록 반환")
     void getPosts_success_returns200() throws Exception {
         PostSummaryResponse summary = new PostSummaryResponse(
-                postId, "Test Post", Level.JUNIOR, userId, "tester", Job.BACKEND, null, Instant.now());
+                postId, "Test Post", Level.JUNIOR, userId, "tester", Job.BACKEND, null, Instant.now(), 2L, "content preview", null);
         PostListResponse listResponse = new PostListResponse(List.of(summary), 0, 20, 1L, 1);
         given(postService.getPosts(any(), any())).willReturn(listResponse);
 
@@ -140,7 +140,7 @@ void getPosts_success_returns200() throws Exception {
     @DisplayName("GET /posts - 목록 응답에 authorJob 필드 포함")
     void getPosts_responseIncludesAuthorJob() throws Exception {
         PostSummaryResponse summary = new PostSummaryResponse(
-                postId, "Test Post", Level.JUNIOR, userId, "tester", Job.FRONTEND, null, Instant.now());
+                postId, "Test Post", Level.JUNIOR, userId, "tester", Job.FRONTEND, null, Instant.now(), 0L, "content preview", null);
         PostListResponse listResponse = new PostListResponse(List.of(summary), 0, 20, 1L, 1);
         given(postService.getPosts(any(), any())).willReturn(listResponse);
 
@@ -153,7 +153,7 @@ void getPosts_responseIncludesAuthorJob() throws Exception {
     @DisplayName("GET /posts - authorJob이 null이어도 정상 반환")
     void getPosts_nullAuthorJob_returns200() throws Exception {
         PostSummaryResponse summary = new PostSummaryResponse(
-                postId, "Test Post", Level.JUNIOR, userId, "tester", null, null, Instant.now());
+                postId, "Test Post", Level.JUNIOR, userId, "tester", null, null, Instant.now(), 0L, "content preview", null);
         PostListResponse listResponse = new PostListResponse(List.of(summary), 0, 20, 1L, 1);
         given(postService.getPosts(any(), any())).willReturn(listResponse);