[Feat]: 게시글 검색 기능 구현

Author: shihan00321

back/src/main/java/com/back/domain/post/repository/PostRepository.java

@@ -8,5 +8,5 @@
  * 게시글 엔티티에 대한 데이터베이스 접근을 담당하는 JpaRepository.
  */
 @Repository
-public interface PostRepository extends JpaRepository<Post, Long> {
+public interface PostRepository extends JpaRepository<Post, Long>, PostRepositoryCustom {
 }

back/src/main/java/com/back/domain/post/repository/PostRepositoryCustom.java

@@ -0,0 +1,10 @@
+package com.back.domain.post.repository;
+
+import com.back.domain.post.dto.PostSearchCondition;
+import com.back.domain.post.entity.Post;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+
+public interface PostRepositoryCustom {
+    Page<Post> searchPosts(PostSearchCondition postSearchCondition, Pageable pageable);
+}

back/src/main/java/com/back/domain/post/repository/PostRepositoryCustomImpl.java

@@ -0,0 +1,74 @@
+package com.back.domain.post.repository;
+
+import com.back.domain.post.dto.PostSearchCondition;
+import com.back.domain.post.entity.Post;
+import com.back.domain.post.enums.PostCategory;
+import com.back.domain.post.enums.SearchType;
+import com.querydsl.core.types.dsl.BooleanExpression;
+import com.querydsl.jpa.impl.JPAQuery;
+import com.querydsl.jpa.impl.JPAQueryFactory;
+import lombok.RequiredArgsConstructor;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.support.PageableExecutionUtils;
+import org.springframework.stereotype.Repository;
+import org.springframework.util.StringUtils;
+
+import java.util.List;
+
+import static com.back.domain.post.entity.QPost.post;
+import static com.back.domain.user.entity.QUser.user;
+
+@RequiredArgsConstructor
+@Repository
+public class PostRepositoryCustomImpl implements PostRepositoryCustom {
+    private final JPAQueryFactory queryFactory;
+
+    @Override
+    public Page<Post> searchPosts(PostSearchCondition condition, Pageable pageable) {
+        List<Post> posts = queryFactory
+                .selectFrom(post)
+                .leftJoin(post.user, user).fetchJoin()
+                .where(getCategoryCondition(condition.category()),
+                        getSearchCondition(condition.keyword(), condition.searchType()))
+                .orderBy(post.createdDate.desc())
+                .offset(pageable.getOffset())
+                .limit(pageable.getPageSize())
+                .fetch();
+
+        JPAQuery<Long> count = queryFactory
+                .select(post.count())
+                .from(post)
+                .where(
+                        getCategoryCondition(condition.category()),
+                        getSearchCondition(condition.keyword(), condition.searchType())
+                );
+
+        return PageableExecutionUtils.getPage(posts, pageable, count::fetchOne);
+    }
+
+    /**
+     * 1차 필터링 (CHAT, SCENARIO, POLL)
+     * category 조건이 null이 아니면 필터링 조건 추가
+     */
+    private BooleanExpression getCategoryCondition(PostCategory category) {
+        return category != null ? post.category.eq(category) : null;
+    }
+
+    /**
+     * 2차 필터링 (TITLE, TITLE_CONTENT, AUTHOR)
+     * fixme 현재 like 기반 검색 - 성능 최적화를 위해 추후에 수정 예정
+     */
+    private BooleanExpression getSearchCondition(String searchKeyword, SearchType searchType) {
+        if (!StringUtils.hasText(searchKeyword) || searchType == null) {
+            return null;
+        }
+
+        return switch (searchType) {
+            case TITLE -> post.title.containsIgnoreCase(searchKeyword);
+            case TITLE_CONTENT -> post.title.containsIgnoreCase(searchKeyword)
+                    .or(post.content.containsIgnoreCase(searchKeyword));
+            case AUTHOR -> post.user.nickname.containsIgnoreCase(searchKeyword);
+        };
+    }
+}