IBotDataStore.FlushAsync Exception: The data is changed

2018-07-01

前言

最新有個需求就是要判斷目前 User 是不是在進行某項作業, 如果不是就推送包含 Button 的訊息給 User, 不然就推文字通知訊息等目前的作業完成後，再顯示待辦的 Button 訊息給 User .

研究

最簡單的就是將這個 flag 寫在 BotState 之中，所以我們可以在使用者加入時，將它的 Conversation 記錄下來，如下，

if (message.Type == ActivityTypes.ConversationUpdate)
{
	Func<ChannelAccount, bool> isChatbot =
		channelAcct => channelAcct.Id == message.Recipient.Id;
	if (message.MembersAdded.Any(isChatbot))
	{
		var memberAdded = message.MembersAdded.FirstOrDefault();
		//這裡請自行處理將該 user 的 Conversation 儲存起來，為了方便，這裡將它存在一個變數之中
		WebApiApplication._ConversationReference = message.ToConversationReference();
	}
}

然後在申請作業記錄這個 Flag ，當然，結束時請記得將這個 Flag 清除哦!

using (var scope = DialogModule.BeginLifetimeScope(Conversation.Container, context.Activity.AsMessageActivity()))
{
	var botDataStore = scope.Resolve<IBotDataStore<BotData>>();
	var key = Address.FromActivity(context.Activity);
	var botUserData = await botDataStore.LoadAsync(key, BotStoreType.BotUserData, default(CancellationToken));
	botUserData.SetProperty<string>("dialog", "RootDialog:MessageReceivedAsync");
	await botDataStore.SaveAsync(key, BotStoreType.BotUserData, botUserData, default(CancellationToken));
	await botDataStore.FlushAsync(key, default(CancellationToken));
}

可是執行時，卻發生了「Exception: The data is changed」的錯誤，如下圖，

因為 botframework 會自動去幫我們將 State 存檔，所以當它存檔時，發現狀態被改掉了，所以就出現「Exception: The data is changed」的錯誤 .

嗯, 那怎麼辦呢? 那就調整程式, 不要去呼叫 FlushAsync, 讓 botframework 去存就可以了, 所以程式調整如下，

using (var scope = DialogModule.BeginLifetimeScope(Conversation.Container, context.Activity.AsMessageActivity()))
{
	var botDataStore = scope.Resolve<IBotDataStore<BotData>>();
	var key = Address.FromActivity(context.Activity);
	var botUserData = await botDataStore.LoadAsync(key, BotStoreType.BotUserData, default(CancellationToken));
	botUserData.SetProperty<string>("dialog", "RootDialog:MessageReceivedAsync");
	await botDataStore.SaveAsync(key, BotStoreType.BotUserData, botUserData, default(CancellationToken));
    //await botDataStore.FlushAsync(key, default(CancellationToken));
}

所以我們的通知程式就可以透過 ConversationReference 轉回 Activity, 取回 BotState, 例如，我新增一個 api method 來顯示 BotState , 如下,

[Route("api/Messages/GetDialogData")]
[HttpGet]
public async Task<HttpResponseMessage> GetDialogData()
{
	var resp = new HttpResponseMessage(HttpStatusCode.OK);
	if (WebApiApplication._ConversationReference != null)
	{
		var message = WebApiApplication._ConversationReference.GetPostToBotMessage();
		using (var scope = DialogModule.BeginLifetimeScope(Conversation.Container, message.AsMessageActivity()))
		{
			var botDataStore = scope.Resolve<IBotDataStore<BotData>>();
			var key = Address.FromActivity(message);
			var botUserData = await botDataStore.LoadAsync(key, BotStoreType.BotUserData, default(CancellationToken));
			var dialogData = botUserData.GetProperty<string>("dialog");
			resp.Content = new StringContent($"<html><body>Dialogs:{dialogData}</body></html>", System.Text.Encoding.UTF8, @"text/html");
		}
	}
	return resp;
}

所以在 Dialog 中儲存 State 時 , 可以注意一下這種狀況哦 ^_^

Demo 專案可以參考 rainmakerho/Exception_DataChanged

參考資料

Microsoft Bot Framework: Exception: The data is changed

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