초대 코드를 사용한 그룹 참여 구현

back/src/main/kotlin/knu/dong/onedayonebaek/controller/GroupController.kt

@@ -11,6 +11,7 @@ import knu.dong.onedayonebaek.domain.User
 import knu.dong.onedayonebaek.dto.CreateGroupRequest
 import knu.dong.onedayonebaek.dto.GroupDetailDto
 import knu.dong.onedayonebaek.dto.JoinGroupRequest
+import knu.dong.onedayonebaek.dto.JoinGroupWithInviteCodeRequest
 import knu.dong.onedayonebaek.exception.InvalidReqParamException
 import knu.dong.onedayonebaek.exception.response.BadRequestResponse
 import knu.dong.onedayonebaek.exception.response.ForbiddenResponse
@@ -118,6 +119,36 @@ class GroupController(
         return groupService.joinGroup(user, groupId, requestDto.password)
     }
 
+    @Operation(
+        summary = "스터디 그룹 참가(초대 코드 사용)",
+        description = "초대 코드를 사용하여 지정된 스터디 그룹을 참가한다."
+    )
+    @PostMapping("/invited")
+    @ApiResponses(
+        ApiResponse(responseCode = "200", description = "참가한 스터디 그룹의 상세 정보"),
+        ApiResponse(responseCode = "400", description = "잘못된 Request Parameter",
+            content = [Content(schema = Schema(implementation = BadRequestResponse::class))]),
+        ApiResponse(responseCode = "404", description = "존재하지 않는 스터디 그룹",
+            content = [Content(schema = Schema(implementation = NotFoundResponse::class))]),
+        ApiResponse(responseCode = "409", description = "- 해당 스터디 그룹에 이미 속해있음",
+            content = [Content(
+                examples = [
+                    ExampleObject(
+                        name = "이미 가입된 그룹",
+                        value = "{\"code\": \"already_joined\", \"message\":\"이미 가입된 스터디 그룹입니다.\"}"
+                    )
+                ],
+                mediaType = MediaType.APPLICATION_JSON_VALUE)])
+    )
+    fun joinGroupWithInviteCode(
+        @Validated @RequestBody requestDto: JoinGroupWithInviteCodeRequest,
+        authentication: Authentication
+    ): GroupDetailDto {
+        val user = authentication.principal as User
+
+        return groupService.joinGroupWithInviteCode(user, requestDto.inviteCode)
+    }
+
     @Operation(
         summary = "그룹 나가기",
         description = "해당 그룹에서 나간다. 그룹장은 나갈 수 없다."

back/src/main/kotlin/knu/dong/onedayonebaek/dto/JoinGroupWithInviteCodeRequest.kt

@@ -0,0 +1,9 @@
+package knu.dong.onedayonebaek.dto
+
+import io.swagger.v3.oas.annotations.media.Schema
+
+@Schema(description = "초대 코드로 그룹 가입 요청 DTO")
+data class JoinGroupWithInviteCodeRequest(
+    @Schema(description = "초대 코드", required = true, example = "q123we")
+    var inviteCode: String
+)

back/src/main/kotlin/knu/dong/onedayonebaek/repository/GroupRepository.kt

@@ -2,6 +2,9 @@ package knu.dong.onedayonebaek.repository
 
 import knu.dong.onedayonebaek.domain.Group
 import org.springframework.data.jpa.repository.JpaRepository
+import java.util.*
 
 interface GroupRepository: JpaRepository<Group, Long> {
+
+    fun findByInviteCode(inviteCode: String): Optional<Group>
 }

back/src/main/kotlin/knu/dong/onedayonebaek/service/GroupService.kt

@@ -94,6 +94,21 @@ class GroupService (
         throw ConflictException("incorrect_password", "비밀번호가 다릅니다.")
     }
 
+    @Transactional
+    fun joinGroupWithInviteCode(user: User, inviteCode: String): GroupDetailDto {
+        val group = groupRepository
+            .findByInviteCode(inviteCode)
+            .orElseThrow{ NotFoundException("해당 그룹이 없습니다.") }
+
+        if (containGroupRepository.existsByGroupAndUser(group, user)) {
+            throw ConflictException("already_joined", "이미 가입된 스터디 그룹입니다.")
+        }
+
+        containGroupRepository.save(ContainGroup(user, group))
+
+        return group.toGroupDetailDto()
+    }
+
     @Transactional
     fun leaveGroup(user: User, groupId: Long) {
         val group = groupRepository.findById(groupId).orElseThrow{ NotFoundException("해당 그룹이 없습니다.") }