客製 BotDataStore ，將 Bot State 資料存到 SQL Server之中

不知大家在使用 botframework-emulator 測試 chatbot 時，有沒有發現，對話一開始時，會先將 Bot State 取出來(BotConversationData, BotPrivateConversationData 及 BotUserData)，而在對話後，則將這些資料存回去，如下圖所示，

那大家會好奇那些 Bot State 都存到那裡去了呢?
預設的 BotDataStore 是使用 ConnectorStore ，它依 StateClient.BotState 去儲存，而 url 就是 {serverUrl}/v3/botstate/{channelId}/conversations/{conversationId} ， {serverUrl}/v3/botstate/{channelId}/conversations/{conversationId}/users/{userId} 及 {serverUrl}/v3/botstate/{channelId}/users/{userId} ，詳細可以參考 BotState.cs ，serverUrl 是 activity.ServiceUrl ，詳細可以參考 StateClient.cs。

在 Saving State data in SQL with .NET 這篇之中，說明如何實作 IBotDataStore 然後將 Bot State 存到 SQL Server 之中。
客製的 BotDataStore 寫好了之後，記得要在 global.asax 中去設定讓 autofac 使用我們的 SqlBotDataStore，如下，

protected void Application_Start()
{
	Conversation.UpdateContainer(builder =>
	{
		var store = new SqlBotDataStore("BotDataContextConnectionString");

		builder.Register(c => new CachingBotDataStore(store  
		    , CachingBotDataStoreConsistencyPolicy.LastWriteWins))
		    .As<IBotDataStore<BotData>>()
		    .AsSelf()
		    .InstancePerLifetimeScope();
	});
	GlobalConfiguration.Configure(WebApiConfig.Register);
}

這樣在SQL中就可以看到 Bot State 存到了 SQL DB 之中，如下，

另外，像我們之前寫的 Local Direct Line Server 使用 Microsoft Bot Framework 地端的 WebChat 機器人(企業內)，我們會將 Channel 的資料放在 ChannelData 之中，而在存 State 時， ChannelId 要取自 activity 的 channelData ，則可以改自 ConnectorStore ，加入讀取 activity ，如下，

//modify from ConnectorStore
public class LDLDataStore : IBotDataStore<BotData>
{
	private readonly IStateClient stateClient;
	private readonly IActivity activity;
	public LDLDataStore(IStateClient stateClient, IActivity activity)
	{
		SetField.NotNull(out this.stateClient, nameof(stateClient), stateClient);
		SetField.NotNull(out this.activity, nameof(activity), activity);
	}

	async Task<BotData> IBotDataStore<BotData>.LoadAsync(IAddress key, BotStoreType botStoreType, CancellationToken cancellationToken)
	{
		var channelId = GetChannelId(key);
		BotData botData;
		switch (botStoreType)
		{
			case BotStoreType.BotConversationData:
				botData = await stateClient.BotState.GetConversationDataAsync(channelId, key.ConversationId, cancellationToken);
				break;
			case BotStoreType.BotUserData:
				botData = await stateClient.BotState.GetUserDataAsync(channelId, key.UserId, cancellationToken);
				break;
			case BotStoreType.BotPrivateConversationData:
				botData = await stateClient.BotState.GetPrivateConversationDataAsync(channelId, key.ConversationId, key.UserId, cancellationToken);
				break;
			default:
				throw new ArgumentException($"{botStoreType} is not a valid store type!");
		}
		return botData;
	}

	async Task IBotDataStore<BotData>.SaveAsync(IAddress key, BotStoreType botStoreType, BotData botData, CancellationToken cancellationToken)
	{
		var channelId = GetChannelId(key);
		switch (botStoreType)
		{
			case BotStoreType.BotConversationData:
				await stateClient.BotState.SetConversationDataAsync(channelId, key.ConversationId, botData, cancellationToken);
				break;
			case BotStoreType.BotUserData:
				await stateClient.BotState.SetUserDataAsync(channelId, key.UserId, botData, cancellationToken);
				break;
			case BotStoreType.BotPrivateConversationData:
				await stateClient.BotState.SetPrivateConversationDataAsync(channelId, key.ConversationId, key.UserId, botData, cancellationToken);
				break;
			default:
				throw new ArgumentException($"{botStoreType} is not a valid store type!");
		}
	}

	Task<bool> IBotDataStore<BotData>.FlushAsync(IAddress key, CancellationToken cancellationToken)
	{
		// Everything is saved. Flush is no-op
		return Task.FromResult(true);
	}

	private string GetChannelId(IAddress key)
	{
		var channelData = JObject.FromObject(activity.ChannelData);
		string channelId = channelData.SelectToken("channelId")?.ToString();
		if (string.IsNullOrWhiteSpace(channelId))
		{
			channelId = key.ChannelId;
		}
		return channelId;
	}
}

而在 global.asax 之中，我們的 LDLDataStore 需要多傳入 Activity ，如下，

protected void Application_Start()
{
    Conversation.UpdateContainer(builder =>
    {
        builder.Register(c => new CachingBotDataStore(new LDLDataStore(c.Resolve<IStateClient>(), c.Resolve<IActivity>())
            , CachingBotDataStoreConsistencyPolicy.LastWriteWins))
            .As<IBotDataStore<BotData>>()
            .AsSelf()
            .InstancePerLifetimeScope();
     });
     GlobalConfiguration.Configure(WebApiConfig.Register);
}

知道如何在 global.asax 中置換 BotDataStore ，只要實作 IBotDataStore 便可以輕易的更換 BotDataStore 哦!

參考資料

Saving State data in SQL with .NET
Manage state data