[FEAT] 질문 답변 조회 기능

plu-api/src/main/kotlin/com/th/plu/api/controller/answer/AnswerController.kt

@@ -0,0 +1,27 @@
+package com.th.plu.api.controller.answer
+
+import com.th.plu.api.config.interceptor.Auth
+import com.th.plu.api.config.resolver.MemberId
+import com.th.plu.api.controller.answer.dto.response.AnswerInfoResponse
+import com.th.plu.api.service.answer.AnswerService
+import com.th.plu.common.dto.response.ApiResponse
+import io.swagger.v3.oas.annotations.Operation
+import io.swagger.v3.oas.annotations.tags.Tag
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.PathVariable
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@Tag(name = "Answer")
+@RestController
+@RequestMapping("/api")
+class AnswerController(
+        private val answerService: AnswerService
+) {
+    @Auth
+    @Operation(summary = "답변 조회")
+    @GetMapping("/v1/answer/{answerId}")
+    fun findAnswerById(@PathVariable answerId: Long, @MemberId memberId: Long): ApiResponse<AnswerInfoResponse> {
+        return ApiResponse.success(answerService.findAnswerInfoById(answerId, memberId))
+    }
+}

plu-api/src/main/kotlin/com/th/plu/api/controller/answer/dto/response/AnswerInfoResponse.kt

@@ -0,0 +1,27 @@
+package com.th.plu.api.controller.answer.dto.response
+
+import com.th.plu.domain.domain.answer.Answer
+import com.th.plu.domain.domain.question.Question
+import java.time.LocalDateTime
+
+data class AnswerInfoResponse(
+        val questionDate: LocalDateTime,
+        val questionTitle: String,
+        val answer: String,
+        val likeCount: Int,
+        val elementImageUrl: String,
+        val colorCode: String
+) {
+    companion object {
+        fun of(question: Question, answer: Answer): AnswerInfoResponse {
+            return AnswerInfoResponse(
+                    questionDate = question.modifiedAt,
+                    questionTitle = question.title,
+                    answer = answer.content,
+                    likeCount = answer.getLikeCount(),
+                    elementImageUrl = question.elementType.elementImageUrl,
+                    colorCode = question.elementType.colorCode
+            )
+        }
+    }
+}

plu-api/src/main/kotlin/com/th/plu/api/service/answer/AnswerService.kt

@@ -0,0 +1,25 @@
+package com.th.plu.api.service.answer
+
+import com.th.plu.api.controller.answer.dto.response.AnswerInfoResponse
+import com.th.plu.domain.domain.answer.explorer.AnswerExplorer
+import com.th.plu.domain.domain.answer.explorer.QuestionExplorer
+import org.springframework.stereotype.Service
+import org.springframework.transaction.annotation.Transactional
+
+@Service
+class AnswerService(
+        private val questionExplorer: QuestionExplorer,
+        private val answerExplorer: AnswerExplorer,
+        private val answerValidator: AnswerValidator
+) {
+    @Transactional(readOnly = true)
+    fun findAnswerInfoById(answerId: Long, memberId: Long): AnswerInfoResponse {
+        val answer = answerExplorer.findAnswerById(answerId)
+        if (!answer.isPublic) {
+            answerValidator.validateIsMemberOwnerOfAnswer(answerId, memberId)
+        }
+        val question = questionExplorer.findQuestionById(answer.getQuestionId())
+
+        return AnswerInfoResponse.of(question, answer)
+    }
+}

plu-api/src/main/kotlin/com/th/plu/api/service/answer/AnswerValidator.kt

@@ -0,0 +1,21 @@
+package com.th.plu.api.service.answer
+
+import com.th.plu.common.exception.code.ErrorCode
+import com.th.plu.common.exception.model.ValidationException
+import com.th.plu.domain.domain.answer.explorer.AnswerExplorer
+import com.th.plu.domain.domain.answer.repository.AnswerRepository
+import org.springframework.stereotype.Component
+
+@Component
+class AnswerValidator(
+        private val answerExplorer: AnswerExplorer,
+        private val answerRepository: AnswerRepository
+) {
+    fun validateIsMemberOwnerOfAnswer(answerId: Long, memberId: Long) {
+        val answer = answerExplorer.findAnswerById(answerId)
+        if (answer.member.id != memberId) {
+            throw ValidationException(ErrorCode.INVALID_ANSWER_OWNER,
+                    "멤버 (ID: ${memberId})는 답변 (ID: ${answerId})의 답변자가 아니기 때문에 답변 정보에 접근할 수 없습니다.")
+        }
+    }
+}

plu-api/src/main/resources/sql/schema.sql

@@ -3,6 +3,7 @@ DROP TABLE IF EXISTS `settings`;
 DROP TABLE IF EXISTS `questions`;
 DROP TABLE IF EXISTS `answers`;
 DROP TABLE IF EXISTS `onboardings`;
+DROP TABLE IF EXISTS `likes`;
 
 
 CREATE TABLE `members`
@@ -54,3 +55,13 @@ CREATE TABLE `onboardings`
     `created_at`    datetime    NOT NULL,
     `modified_at`   datetime    NOT NULL
 );
+
+CREATE TABLE `likes`
+(
+    `like_id`     bigint auto_increment primary key,
+    `question_id` bigint   NOT NULL,
+    `answer_id`   bigint   NOT NULL,
+    `member_id`   bigint   NOT NULL,
+    `created_at`  datetime NOT NULL,
+    `modified_at` datetime NOT NULL
+);

plu-common/src/main/kotlin/com/th/plu/common/exception/code/ErrorCode.kt

@@ -10,6 +10,7 @@ enum class ErrorCode(val code: String, val message: String) {
     BIND_EXCEPTION("V005", "요청 값을 바인딩하는 과정에서 오류가 발생하였습니다."),
     METHOD_ARGUMENT_NOT_VALID_EXCEPTION("V006", "요청 값이 검증되지 않은 값 입니다."),
     INVALID_FORMAT_EXCEPTION("V007", "요청 값이 유효하지 않은 데이터입니다."),
+    INVALID_ANSWER_OWNER("V008", "질문의 소유자가 아닙니다."),
 
     // Unauthorized Exception
     UNAUTHORIZED_EXCEPTION("U001", "토큰이 만료되었습니다. 다시 로그인 해주세요."),
@@ -21,6 +22,8 @@ enum class ErrorCode(val code: String, val message: String) {
     // NotFound Exception
     NOT_FOUND_EXCEPTION("N001", "존재하지 않습니다."),
     NOT_FOUND_MEMBER_EXCEPTION("N002", "탈퇴했거나 존재하지 않는 회원입니다."),
+    NOT_FOUND_ANSWER_EXCEPTION("N003", "존재하지 않는 답변입니다."),
+    NOT_FOUND_QUESTION_EXCEPTION("N004", "존재하지 않는 질문입니다."),
     NOT_FOUND_ARTICLE_CONTENT_EXCEPTION("N003", "아티클의 컨텐츠가 존재하지 않습니다."),
     NOT_FOUND_CHALLENGE_EXCEPTION("N004", "존재하지 않는 챌린지입니다."),
     NOT_FOUND_ARTICLE_EXCEPTION("N005", "삭제되었거나 존재하지 않는 아티클입니다."),

plu-domain/src/main/kotlin/com/th/plu/domain/domain/answer/Answer.kt

@@ -1,6 +1,7 @@
 package com.th.plu.domain.domain.answer
 
 import com.th.plu.domain.domain.common.BaseEntity
+import com.th.plu.domain.domain.like.Like
 import com.th.plu.domain.domain.member.Member
 import com.th.plu.domain.domain.question.Question
 import jakarta.persistence.*
@@ -17,23 +18,34 @@ import lombok.NoArgsConstructor
 @Builder(access = AccessLevel.PRIVATE)
 class Answer(
 
-    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
-    @Column(name = "answer_id")
-    private var id: Long? = null,
+        @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
+        @Column(name = "answer_id")
+        var id: Long? = null,
 
-    @ManyToOne(fetch = FetchType.LAZY, cascade = [CascadeType.ALL])
-    @JoinColumn(name = "member_id", nullable = false)
-    private var member: Member,
+        @ManyToOne(fetch = FetchType.LAZY, cascade = [CascadeType.ALL])
+        @JoinColumn(name = "member_id", nullable = false)
+        var member: Member,
 
-    @ManyToOne(fetch = FetchType.LAZY, cascade = [CascadeType.ALL])
-    @JoinColumn(name = "question_id", nullable = false)
-    private var question: Question,
+        @ManyToOne(fetch = FetchType.LAZY, cascade = [CascadeType.ALL])
+        @JoinColumn(name = "question_id", nullable = false)
+        var question: Question,
 
-    @Column(name = "answer_content", nullable = false)
-    private var content: String,
+        @Column(name = "answer_content", nullable = false)
+        var content: String,
 
-    @Column(name = "is_public", nullable = false)
-    private var isPublic: Boolean
+        @Column(name = "is_public", nullable = false)
+        var isPublic: Boolean,
+
+        @OneToMany(mappedBy = "answer", fetch = FetchType.LAZY, cascade = [CascadeType.ALL], orphanRemoval = true)
+        var likes: List<Like> = mutableListOf()
 
 ) : BaseEntity() {
+
+    fun getLikeCount(): Int {
+        return likes.size
+    }
+
+    fun getQuestionId(): Long {
+        return question.id!!
+    }
 }

plu-domain/src/main/kotlin/com/th/plu/domain/domain/answer/explorer/AnswerExplorer.kt

@@ -0,0 +1,17 @@
+package com.th.plu.domain.domain.answer.explorer
+
+import com.th.plu.common.exception.code.ErrorCode
+import com.th.plu.common.exception.model.NotFoundException
+import com.th.plu.domain.domain.answer.Answer
+import com.th.plu.domain.domain.answer.repository.AnswerRepository
+import org.springframework.stereotype.Component
+
+@Component
+class AnswerExplorer(
+        private val answerRepository: AnswerRepository
+) {
+    fun findAnswerById(id: Long): Answer {
+        return answerRepository.findAnswerById(id)
+                ?: throw NotFoundException(ErrorCode.NOT_FOUND_ANSWER_EXCEPTION, "존재하지 않는 답변(ID: $id) 입니다")
+    }
+}

plu-domain/src/main/kotlin/com/th/plu/domain/domain/like/Like.kt

@@ -0,0 +1,43 @@
+package com.th.plu.domain.domain.like
+
+import com.th.plu.domain.domain.answer.Answer
+import com.th.plu.domain.domain.common.BaseEntity
+import com.th.plu.domain.domain.member.Member
+import com.th.plu.domain.domain.question.Question
+import jakarta.persistence.*
+
+@Table(name = "likes")
+@Entity
+class Like(
+
+        @Id
+        @GeneratedValue(strategy = GenerationType.IDENTITY)
+        @Column(name = "like_id")
+        var id: Long? = null,
+
+        @ManyToOne(fetch = FetchType.LAZY, cascade = [CascadeType.ALL])
+        @JoinColumn(name = "member_id", nullable = false)
+        var member: Member,
+
+        @ManyToOne(fetch = FetchType.LAZY, cascade = [CascadeType.ALL])
+        @JoinColumn(name = "answer_id", nullable = false)
+        var answer: Answer,
+
+        @ManyToOne(fetch = FetchType.LAZY, cascade = [CascadeType.ALL])
+        @JoinColumn(name = "question_id", nullable = false)
+        var question: Question
+
+) : BaseEntity() {
+
+    companion object {
+        fun newInstance(
+                member: Member, answer: Answer, question: Question
+        ): Like {
+            return Like(
+                    member = member,
+                    answer = answer,
+                    question = question
+            )
+        }
+    }
+}

plu-domain/src/main/kotlin/com/th/plu/domain/domain/like/repository/LikeRepository.kt

@@ -0,0 +1,7 @@
+package com.th.plu.domain.domain.like.repository
+
+import com.th.plu.domain.domain.member.Member
+import org.springframework.data.jpa.repository.JpaRepository
+
+interface LikeRepository : JpaRepository<Member, Long>, LikeRepositoryCustom {
+}

plu-domain/src/main/kotlin/com/th/plu/domain/domain/like/repository/LikeRepositoryCustom.kt

@@ -0,0 +1,8 @@
+package com.th.plu.domain.domain.like.repository
+
+import com.th.plu.domain.domain.like.Like
+
+interface LikeRepositoryCustom {
+
+    fun findLikeById(id: Long): Like?
+}

plu-domain/src/main/kotlin/com/th/plu/domain/domain/like/repository/LikeRepositoryImpl.kt

@@ -0,0 +1,16 @@
+package com.th.plu.domain.domain.like.repository
+
+import com.querydsl.jpa.impl.JPAQueryFactory
+import com.th.plu.domain.domain.like.Like
+import com.th.plu.domain.domain.like.QLike.like
+import org.springframework.stereotype.Repository
+
+@Repository
+class LikeRepositoryImpl(private val queryFactory: JPAQueryFactory) : LikeRepositoryCustom {
+    override fun findLikeById(id: Long): Like? {
+        return queryFactory
+                .selectFrom(like)
+                .where(like.id.eq(id))
+                .fetchOne();
+    }
+}

plu-domain/src/main/kotlin/com/th/plu/domain/domain/question/ElementType.kt

@@ -1,9 +1,9 @@
 package com.th.plu.domain.domain.question
 
 enum class ElementType(
-    private val characterImageUrl: String,
-    private val elementImageUrl: String,
-    private val colorCode: String
+        val characterImageUrl: String,
+        val elementImageUrl: String,
+        val colorCode: String
 ) {
     // TODO: 엘리먼트 네이밍 체크 필요
     WATER("", "", ""),

plu-domain/src/main/kotlin/com/th/plu/domain/domain/question/explorer/QuestionExplorer.kt

@@ -0,0 +1,17 @@
+package com.th.plu.domain.domain.answer.explorer
+
+import com.th.plu.common.exception.code.ErrorCode
+import com.th.plu.common.exception.model.NotFoundException
+import com.th.plu.domain.domain.question.Question
+import com.th.plu.domain.domain.question.repository.QuestionRepository
+import org.springframework.stereotype.Component
+
+@Component
+class QuestionExplorer(
+        private val questionRepository: QuestionRepository
+) {
+    fun findQuestionById(id: Long): Question {
+        return questionRepository.findQuestionById(id)
+                ?: throw NotFoundException(ErrorCode.NOT_FOUND_QUESTION_EXCEPTION, "존재하지 않는 질문(ID: $id) 입니다")
+    }
+}