修复了一些逻辑漏洞

internal/api/conversation_handler.go

@@ -122,7 +122,7 @@ func DeleteConversationHandler(c *gin.Context) {
 
 /**
  * GetConversationByRoomHandler
- * 功能：根据 room_id 获取或创建会话
+ * 功能：根据 room_id 获取会话（不自动创建）
  * 路径：GET /api/conversations/by-room/:room_id
  */
 func GetConversationByRoomHandler(c *gin.Context) {
@@ -137,7 +137,7 @@ func GetConversationByRoomHandler(c *gin.Context) {
 	conv, err := service.ConversationSvc.GetOrCreateConversationByRoom(userID.(string), roomID)
 	if err != nil {
 		if err == gorm.ErrRecordNotFound {
-			utils.NotFound(c, "房间不存在或无权访问")
+			utils.NotFound(c, "会话不存在")
 		} else {
 			utils.InternalError(c, "查询失败")
 		}

internal/service/conversation_service.go

@@ -116,6 +116,15 @@ func (s *ConversationService) UpsertConversationOnMessage(userID, targetID, room
 			if !isSender {
 				conv.UnreadCount = 1
 			}
+			
+			// 群聊时，target_id 是群ID，不是用户ID，需要临时禁用外键检查
+			if conversationType == 2 {
+				s.DB.Exec("SET FOREIGN_KEY_CHECKS = 0")
+				err := s.DB.Create(&conv).Error
+				s.DB.Exec("SET FOREIGN_KEY_CHECKS = 1")
+				return err
+			}
+			
 			return s.DB.Create(&conv).Error
 		}
 		return tx.Error
@@ -272,15 +281,19 @@ func (s *ConversationService) GetOrCreateConversationByRoom(userID, roomID strin
 		return nil, gorm.ErrRecordNotFound
 	}
 
-	// 查询房间信息以确定类型
+	// 先查询房间信息（必须存在才能创建会话）
 	var room model.ChatRoom
 	roomErr := s.DB.Where("room_id = ?", roomID).First(&room).Error
 	
+	if roomErr != nil {
+		// 房间不存在，返回错误
+		return nil, gorm.ErrRecordNotFound
+	}
+	
 	var conversationType int
 	var targetID string
 	
-	if roomErr == nil {
-		// 房间存在，根据房间类型判断
+	// 根据房间类型判断会话类型
 	if room.RoomType == "group" {
 		conversationType = 2 // 群聊
 		targetID = roomID    // 群聊时 targetID = roomID
@@ -301,27 +314,6 @@ func (s *ConversationService) GetOrCreateConversationByRoom(userID, roomID strin
 			return nil, gorm.ErrRecordNotFound
 		}
 	}
-	} else {
-		// 房间不存在，尝试通过 roomID 格式判断
-		if len(roomID) > 6 && roomID[:6] == "group_" {
-			conversationType = 2 // 群聊
-			targetID = roomID
-		} else {
-			// 可能是私聊，尝试从 room_members 查找
-			var members []model.RoomMember
-			if err := s.DB.Where("room_id = ?", roomID).Find(&members).Error; err == nil && len(members) == 2 {
-				conversationType = 1 // 私聊
-				for _, member := range members {
-					if member.UserID != userID {
-						targetID = member.UserID
-						break
-					}
-				}
-			} else {
-				return nil, gorm.ErrRecordNotFound
-			}
-		}
-	}
 
 	// 查询会话
 	var conv model.ChatConversation
@@ -329,7 +321,7 @@ func (s *ConversationService) GetOrCreateConversationByRoom(userID, roomID strin
 	
 	if tx.Error != nil {
 		if tx.Error == gorm.ErrRecordNotFound {
-			// 创建新会话
+			// 会话不存在，根据房间信息创建新会话
 			conv = model.ChatConversation{
 				UserID:      userID,
 				TargetID:    targetID,
@@ -339,9 +331,20 @@ func (s *ConversationService) GetOrCreateConversationByRoom(userID, roomID strin
 				LastTime:    time.Now(),
 				UnreadCount: 0,
 			}
+			
+			// 群聊时，target_id 是群ID，不是用户ID，需要临时禁用外键检查
+			if conversationType == 2 {
+				s.DB.Exec("SET FOREIGN_KEY_CHECKS = 0")
+				err := s.DB.Create(&conv).Error
+				s.DB.Exec("SET FOREIGN_KEY_CHECKS = 1")
+				if err != nil {
+					return nil, err
+				}
+			} else {
 				if err := s.DB.Create(&conv).Error; err != nil {
 					return nil, err
 				}
+			}
 		} else {
 			return nil, tx.Error
 		}
@@ -356,19 +359,7 @@ func (s *ConversationService) GetOrCreateConversationByRoom(userID, roomID strin
 			log.Printf("⚠️ 用户信息查询失败 (user_id: %s): %v", conv.TargetID, err)
 		}
 	} else if conv.Type == 2 { // 群聊：加载群信息
-		if roomErr == nil {
-			// 之前查询成功，直接使用
 		conv.Room = &room
-		} else {
-			// 如果之前查询失败，再次尝试查询
-			var retryRoom model.ChatRoom
-			if err := s.DB.Where("room_id = ?", roomID).First(&retryRoom).Error; err == nil {
-				conv.Room = &retryRoom
-			} else {
-				log.Printf("⚠️ 群聊信息查询失败 (room_id: %s): %v", roomID, err)
-				// 即使查询失败，也返回会话，但 Room 字段为 nil
-			}
-		}
 	}
 
 	return &conv, nil