feat: HashTag 구현

src/main/java/com/milk/milkweb/entity/Board.java

@@ -9,7 +9,9 @@
 
 import java.time.LocalDateTime;
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 
 @Entity
@@ -43,6 +45,9 @@ public class Board {
 	@OneToMany(mappedBy = "board", cascade = CascadeType.ALL, orphanRemoval = true)
 	private final List<Comment> comments = new ArrayList<>();
 
+	@OneToMany(mappedBy = "board", cascade = CascadeType.ALL, orphanRemoval = true)
+	private final Set<BoardHashTag> tags = new HashSet<>();
+
 	@ManyToOne(fetch = FetchType.LAZY)
 	@JoinColumn(name = "member_id")
 	private Member member;

src/main/java/com/milk/milkweb/entity/BoardHashTag.java

@@ -0,0 +1,35 @@
+package com.milk.milkweb.entity;
+
+import jakarta.persistence.*;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Entity
+@Table(name = "board_hash_tag")
+@Getter @Builder
+@AllArgsConstructor @NoArgsConstructor
+public class BoardHashTag {
+
+	@Id
+	@Column(name = "b_hash_tag_id")
+	@GeneratedValue(strategy = GenerationType.AUTO)
+	private Long id;
+
+	@ManyToOne(fetch = FetchType.LAZY)
+	@JoinColumn(name = "board_id")
+	private Board board;
+
+	@ManyToOne(fetch = FetchType.LAZY)
+	@JoinColumn(name = "hash_tag_id")
+	private HashTag hashTag;
+
+	public static BoardHashTag of(Board board, HashTag tag) {
+		return BoardHashTag.builder()
+				.board(board)
+				.hashTag(tag)
+				.build();
+	}
+
+}

src/main/java/com/milk/milkweb/entity/HashTag.java

@@ -0,0 +1,29 @@
+package com.milk.milkweb.entity;
+
+import jakarta.persistence.*;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Entity
+@Table(name = "hash_tag")
+@Getter @Builder
+@AllArgsConstructor @NoArgsConstructor
+public class HashTag {
+
+	@Id
+	@Column(name = "hash_tag_id")
+	@GeneratedValue(strategy = GenerationType.AUTO)
+	private Long id;
+
+	@Column(nullable = false, unique = true)
+	private String tag;
+
+	public static HashTag of (String tag) {
+		return HashTag.builder()
+				.tag(tag)
+				.build();
+	}
+
+}

src/main/java/com/milk/milkweb/repository/BoardHashTagRepository.java

@@ -0,0 +1,11 @@
+package com.milk.milkweb.repository;
+
+import com.milk.milkweb.entity.BoardHashTag;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.List;
+
+public interface BoardHashTagRepository extends JpaRepository<BoardHashTag, Long> {
+
+	List<BoardHashTag> findAllByBoardId(Long boardId);
+}

src/main/java/com/milk/milkweb/repository/HashTagRepository.java

@@ -0,0 +1,14 @@
+package com.milk.milkweb.repository;
+
+import com.milk.milkweb.entity.HashTag;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.Optional;
+
+public interface HashTagRepository extends JpaRepository<HashTag, Long> {
+
+	Boolean existsByTag(String tag);
+
+	Optional<HashTag> findByTag(String tag);
+
+}

src/main/java/com/milk/milkweb/service/HashTagService.java

@@ -0,0 +1,64 @@
+package com.milk.milkweb.service;
+
+
+import com.milk.milkweb.entity.Board;
+import com.milk.milkweb.entity.BoardHashTag;
+import com.milk.milkweb.entity.HashTag;
+import com.milk.milkweb.repository.BoardHashTagRepository;
+import com.milk.milkweb.repository.HashTagRepository;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+@Service
+@Transactional
+@RequiredArgsConstructor
+@Slf4j
+public class HashTagService {
+
+	private final HashTagRepository hashTagRepository;
+	private final BoardHashTagRepository boardHashTagRepository;
+
+
+	public void saveHashTag(Set<String> dtoTags, Board board) {
+		if (dtoTags.isEmpty()) return;
+
+		List<HashTag> hashTags = dtoTags.stream()
+				.filter(s -> !hashTagRepository.existsByTag(s))
+				.map(HashTag::of)
+				.toList();
+		log.info("saveHashTag -> hashTagRepository.saveAll");
+		hashTagRepository.saveAll(hashTags);
+
+		List<BoardHashTag> boardHashTags = dtoTags.stream()
+				.map(hashTagRepository::findByTag)
+				.filter(Optional::isPresent)
+				.map(Optional::get)
+				.map(tag -> BoardHashTag.of(board, tag))
+				.toList();
+		log.info("saveHashTag -> boardHashTagRepository.saveAll");
+		boardHashTagRepository.saveAll(boardHashTags);
+	}
+
+
+	@Transactional(readOnly = true)
+	public Set<String> readHashTag(Long boardId) {
+		return boardHashTagRepository.findAllByBoardId(boardId).stream()
+				.map(boardHashTag -> boardHashTag.getHashTag().getTag())
+				.collect(Collectors.toSet());
+	}
+
+	public void DeleteBoardTag(Long boardId, Set<String> dtoTags) {
+		List<BoardHashTag> boardHashTags = boardHashTagRepository.findAllByBoardId(boardId);
+
+		List<BoardHashTag> deleteBoardTags = boardHashTags.stream()
+				.filter(t -> !dtoTags.contains(t.getHashTag().getTag()))
+				.toList();
+		boardHashTagRepository.deleteAll(deleteBoardTags);
+
+	}
+}