#163 refactor: 채팅방목록 조회시 메세지가 없다면 null 을반환하도록 한다. (#164)

* #163 refactor: 채팅방목록 조회시 메세지가 없다면 null 을반환하도록 한다.

* #163 refactor: null 값 대신 optional 을 return 하도록 수정

secondhand/src/main/java/com/codesquad/secondhand/domain/chat/dto/response/ChatRoomMessageResponse.java

@@ -6,14 +6,22 @@
 
 import lombok.Builder;
 import lombok.Getter;
+import lombok.NoArgsConstructor;
 
 @Getter
 @Builder
+@NoArgsConstructor
 public class ChatRoomMessageResponse {
 	private LocalDateTime sendAt;
 	private String message;
 	private Long unreadMessageCount;
 
+	public ChatRoomMessageResponse(LocalDateTime sendAt, String message, Long unreadMessageCount) {
+		this.sendAt = sendAt;
+		this.message = message;
+		this.unreadMessageCount = unreadMessageCount;
+	}
+
 	public static ChatRoomMessageResponse of(ChatMessage chatMessage, Long count) {
 		return ChatRoomMessageResponse.builder()
 			.sendAt(chatMessage.getSendAt())

secondhand/src/main/java/com/codesquad/secondhand/domain/chat/repository/ChatMessageQueryRepository.java

@@ -2,6 +2,8 @@
 
 import static com.codesquad.secondhand.domain.chat.entity.QChatMessage.*;
 
+import java.util.Optional;
+
 import org.springframework.stereotype.Repository;
 
 import com.codesquad.secondhand.domain.chat.entity.ChatMessage;
@@ -15,12 +17,12 @@
 public class ChatMessageQueryRepository {
 	private final JPAQueryFactory query;
 
-	public ChatMessage findLatestMessage(ChatRoom chatRoom) {
+	public Optional<ChatMessage> findLatestMessage(ChatRoom chatRoom) {
 		ChatMessage latestMessage = query
 			.selectFrom(chatMessage)
 			.where(chatMessage.chatRoom.eq(chatRoom))
 			.orderBy(chatMessage.sendAt.desc())
 			.fetchFirst();
-		return latestMessage;
+		return Optional.ofNullable(latestMessage);
 	}
 }

secondhand/src/main/java/com/codesquad/secondhand/domain/chat/service/ChatQueryService.java

@@ -1,6 +1,7 @@
 package com.codesquad.secondhand.domain.chat.service;
 
 import java.util.List;
+import java.util.Optional;
 
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
@@ -60,7 +61,7 @@ public Long getUnReadCount(Member opponent, ChatRoom chatRoom) {
 		return chatMessageJpaRepository.countUnreadMessages(opponent, chatRoom);
 	}
 
-	public ChatMessage findLastMessage(ChatRoom chatRoom) {
+	public Optional<ChatMessage> findLastMessage(ChatRoom chatRoom) {
 		return chatMessageQueryRepository.findLatestMessage(chatRoom);
 	}
 

secondhand/src/main/java/com/codesquad/secondhand/domain/chat/service/ChatService.java

@@ -1,6 +1,7 @@
 package com.codesquad.secondhand.domain.chat.service;
 
 import java.util.List;
+import java.util.Optional;
 import java.util.stream.Collectors;
 
 import org.springframework.stereotype.Service;
@@ -106,7 +107,8 @@ public List<ChatRoomListResponse> getChatRoomList(Long memberId) {
 			.map(chatRoom -> {
 				ChatRoomProductResponse productResponse = mapToChatRoomProduct(chatRoom);
 				ChatRoomOpponentResponse opponentResponse = mapToChatRoomOpponent(chatRoom, memberId);
-				ChatRoomMessageResponse chatRoomMessageResponse = mapToChatRoomMessage(chatRoom, memberId);
+				ChatRoomMessageResponse chatRoomMessageResponse = mapToChatRoomMessage(chatRoom, memberId)
+					.orElseGet(() -> new ChatRoomMessageResponse());
 				return ChatRoomListResponse.of(chatRoom.getId(), productResponse, opponentResponse,
 					chatRoomMessageResponse);
 			}).collect(Collectors.toList());
@@ -122,11 +124,15 @@ private ChatRoomOpponentResponse mapToChatRoomOpponent(ChatRoom chatRoom, Long m
 		return ChatRoomOpponentResponse.of(member.getNickname(), member.getProfileImg());
 	}
 
-	private ChatRoomMessageResponse mapToChatRoomMessage(ChatRoom chatRoom, Long memberId) {
-		ChatMessage message = chatQueryService.findLastMessage(chatRoom);
+	private Optional<ChatRoomMessageResponse> mapToChatRoomMessage(ChatRoom chatRoom, Long memberId) {
+		Optional<ChatMessage> optionalMessage = chatQueryService.findLastMessage(chatRoom);
+		if (!optionalMessage.isPresent()) {
+			return Optional.empty();
+		}
+		ChatMessage message = optionalMessage.get();
 		Member member = findOpponentMember(chatRoom, memberId);
 		Long count = chatQueryService.getUnReadCount(member, chatRoom);
-		return ChatRoomMessageResponse.of(message, count);
+		return Optional.of(ChatRoomMessageResponse.of(message, count));
 	}
 
 	private Member findOpponentMember(ChatRoom chatRoom, Long memberId) {