[spring kotlin] 게시판 좋아요 api 설계

                                    CREATE TABLE LIKES(
    id BIGINT AUTO_INCREMENT PRIMARY KEY, -- 기본키
    board_id BIGINT NOT NULL,
    user_id BIGINT NOT NULL,
    -- 개념적 foreign key로 설정(실제 DB에는 외래키로 반영하지 읂음)
    type INT NOT NULL
)

                                    CREATE INDEX idx_board_id
ON likes(board_id);

                                    CREATE INDEX idx_user_id
ON likes(board_id);

                                    package com.example.frontServer.entity

import jakarta.persistence.*
import org.springframework.data.annotation.CreatedBy

@Entity
@Table(
    name = "likes",
)
class Like(
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    var id: Long? = null,

    @Column(name = "board_id")
    val boardId: Long,

    @Column(name = "user_id")
    var userId: Long? = null,
)

                                    // import 생략

@RestController
class LikeController(
    private val likeService: LikeService,
) {

    @PostMapping("/like")
    fun save(
        @RequestBody saveDto: LikeSaveDto
    ): ResponseEntity<ResponseToServerDto> {
        likeService.save(saveDto)
        return ResponseEntity.ok().body(
            ResponseToServerDto(
                error = null,
                userIds = null
            )
        )
    }

    @DeleteMapping("/like")
    fun delete(
        @RequestBody boardId: Long
    ): ResponseEntity<ResponseToServerDto> {
        likeService.delete(boardId)
        return ResponseEntity.ok().body(
            ResponseToServerDto(
                error = null,
                userIds = null
            )
        )
    }

    @GetMapping("/like/users")
    fun findUserIdsByBoardId(
        @RequestParam boardId: Long,
    ): ResponseEntity<ResponseToServerDto> {
        return ResponseEntity.ok().body(
            ResponseToServerDto(
                error = null,
                userIds = likeService.findUserIdsByBoardId(boardId)
            )
        )
    }
}

                                    package com.example.liveApiServer.service

import com.example.liveApiServer.dto.LikeSaveDto
import com.example.liveApiServer.entity.Like
import com.example.liveApiServer.repository.LikeRepository
import org.springframework.stereotype.Service

@Service
class LikeService(
    private val likeRepository: LikeRepository,
) {
    fun save(saveDto: LikeSaveDto){
        likeRepository.save(
            Like(
                id = null, // 이렇게 직접 명시해주기.
                boardId = saveDto.boardId,
                userId = saveDto.userId,
                likeType = saveDto.likeType,
            )
        )
        // boardId userId가 없는 경우 어떻게 처리?
        // likeType이 없는 type인 경우도 있을 수 있다.
        // Exception?
    }

    fun delete(boardId: Long) {
        likeRepository.deleteLogically(boardId)
    }

    fun findUserIdsByBoardId(boardId: Long): List<Long> {
        return likeRepository.findByBoardId(boardId).map {it.userId}
    }
}

                                    package com.example.liveApiServer.repository

import com.example.liveApiServer.entity.Like
import org.springframework.data.jpa.repository.JpaRepository

interface LikeRepository: JpaRepository<Like, Long>, LikeQueryDslRepository {
    fun findByBoardId(boardId: Long): List<Like>
}

                                    package com.example.liveApiServer.repository

import com.example.liveApiServer.entity.Like
import com.example.liveApiServer.entity.QLike
import com.example.liveApiServer.enum.LikeType
import com.querydsl.jpa.impl.JPAQueryFactory

class LikeQueryDslRepositoryImpl(
    private val queryFactory: JPAQueryFactory
):LikeQueryDslRepository {
    private val like = QLike.like
    override fun deleteLogically(boardId: Long) {
        queryFactory
            .update(like)
            .set(like.likeType, LikeType.NONE.ordinal)
            .where(like.boardId.eq(boardId))
            .execute()
    }
}

                                    package com.example.liveApiServer.enum

enum class LikeType {
    NONE,

    LIKE,

    SMILE,

    SAD,

    AMAZING
}

                                    package com.example.liveApiServer.dto

data class LikeSaveDto(
    val boardId: Long,
    val userId: Long,
    val likeType: Int,
)