feat : post 생성 관련 기능

src/main/java/com/snsIntegrationFeedService/hashtag/repository/HashtagRepository.java

@@ -0,0 +1,11 @@
+package com.snsIntegrationFeedService.hashtag.repository;
+
+import com.snsIntegrationFeedService.hashtag.entity.Hashtag;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface HashtagRepository extends JpaRepository<Hashtag, Long> {
+
+    Long findIdByName(String hashtag);
+}

src/main/java/com/snsIntegrationFeedService/hashtag/service/HashtagService.java

@@ -0,0 +1,23 @@
+package com.snsIntegrationFeedService.hashtag.service;
+
+import com.snsIntegrationFeedService.hashtag.entity.Hashtag;
+import com.snsIntegrationFeedService.hashtag.repository.HashtagRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+
+@Service
+@RequiredArgsConstructor
+public class HashtagService {
+
+    private final HashtagRepository hashtagRepository;
+
+    public Hashtag createHashtag(String tag) {
+        Hashtag hashtag = Hashtag.builder().name(tag).build();
+
+        return hashtagRepository.save(hashtag);
+    }
+
+    public Long getHashtagId(String hashtag) {
+        return hashtagRepository.findIdByName(hashtag);
+    }
+}

src/main/java/com/snsIntegrationFeedService/post/service/PostService.java

@@ -1,5 +1,10 @@
 package com.snsIntegrationFeedService.post.service;
 
+import com.snsIntegrationFeedService.hashtag.entity.Hashtag;
+import com.snsIntegrationFeedService.hashtag.service.HashtagService;
+import com.snsIntegrationFeedService.post.dto.request.CreatePostRequest;
+import com.snsIntegrationFeedService.postHashtag.service.PostHashtagService;
+import com.snsIntegrationFeedService.user.entity.User;
 import java.util.List;
 
 import org.springframework.stereotype.Service;
@@ -21,6 +26,9 @@ public class PostService {
 
 	private final PostRepository postRepository;
 
+	private final HashtagService hashtagService;
+	private final PostHashtagService postHashtagService;
+
 	@Transactional
 	public PostDetailResponseDto getPostDetail(String postId) {
 		// 예외 처리
@@ -37,4 +45,17 @@ public PostDetailResponseDto getPostDetail(String postId) {
 		post.view();
 		return PostDetailResponseDto.from(post, hashTags);
 	}
+
+	public Post createPost(User user, CreatePostRequest request) {
+		// post 생성
+		Post savedPost = postRepository.save(request.toEntity(user, request));
+
+		// hashtag 생성
+		Hashtag hashtag = hashtagService.createHashtag(request.getHashtag());
+
+		// postHashtag 생성
+		postHashtagService.createPostHashtag(savedPost, hashtag);
+
+		return savedPost;
+	}
 }

src/main/java/com/snsIntegrationFeedService/postHashtag/entity/PostHashtag.java

@@ -3,6 +3,7 @@
 import com.snsIntegrationFeedService.hashtag.entity.Hashtag;
 import com.snsIntegrationFeedService.post.entity.Post;
 import jakarta.persistence.*;
+import lombok.Builder;
 import lombok.Getter;
 
 @Entity
@@ -19,4 +20,14 @@ public class PostHashtag {
 	@ManyToOne(fetch = FetchType.LAZY)
 	@JoinColumn(name = "hashtag_id")
 	private Hashtag hashtag;
+
+	@Builder
+	public PostHashtag(Post post, Hashtag hashtag) {
+		this.post = post;
+		this.hashtag = hashtag;
+	}
+
+	public PostHashtag() {
+
+	}
 }

src/main/java/com/snsIntegrationFeedService/postHashtag/repository/PostHashtagRepository.java

@@ -0,0 +1,13 @@
+package com.snsIntegrationFeedService.postHashtag.repository;
+
+import com.snsIntegrationFeedService.postHashtag.entity.PostHashtag;
+import java.util.List;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+
+public interface PostHashtagRepository extends JpaRepository<PostHashtag, Long> {
+
+    @Query(value = "SELECT post_id FROM post_hashtag WHERE hashtag_id = :hashtagId", nativeQuery = true)
+    List<Long> findPostIdsByHashtagId(@Param("hashtagId") Long hashtagId);
+}

src/main/java/com/snsIntegrationFeedService/postHashtag/service/PostHashtagService.java

@@ -0,0 +1,32 @@
+package com.snsIntegrationFeedService.postHashtag.service;
+
+import com.snsIntegrationFeedService.hashtag.entity.Hashtag;
+import com.snsIntegrationFeedService.hashtag.service.HashtagService;
+import com.snsIntegrationFeedService.post.entity.Post;
+import com.snsIntegrationFeedService.postHashtag.entity.PostHashtag;
+import com.snsIntegrationFeedService.postHashtag.repository.PostHashtagRepository;
+import java.util.List;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+
+@Service
+@RequiredArgsConstructor
+public class PostHashtagService {
+
+    private final PostHashtagRepository postHashtagRepository;
+    private final HashtagService hashtagService;
+
+    public PostHashtag createPostHashtag(Post post, Hashtag hashtag) {
+        PostHashtag postHashtag = PostHashtag.builder()
+                .post(post)
+                .hashtag(hashtag)
+                .build();
+        return postHashtagRepository.save(postHashtag);
+    }
+
+    public List<Long> getPostIdsByHashtag(String hashtag) {
+        Long hashtagId = hashtagService.getHashtagId(hashtag);
+
+        return postHashtagRepository.findPostIdsByHashtagId(hashtagId);
+    }
+}