private async Task <Group> AddToGroup(string groupName) { var group = await _messageService.GetMessageGroup(groupName); var connection = new Connection(Context.ConnectionId, Context.User.GetUserId()); if (group == null) { group = new Group(groupName); _messageService.AddGroup(group); } group.Connections.Add(connection); if (await _messageService.SaveAllAsync()) { return(group); } throw new HubException("Fail to join the chat"); }