给公众号接入FastWiki智能AI知识库，让您的公众号加入智能行列

2024-05-17码农

最近由于公众号用户太多，我就在思考有啥方式能给微信公众号的粉丝提供更多的更好的服务？这个时候我就想是否可以给公众号接入一下AI？让用户跟微信公众号对话，然后还能回答用户的问题，并且我提供一些资料让AI帮我回复用户的信息？

这个时候刚刚好我们的 FastWiki 项目满足了部分需求，然后我们就顺便加入了微信公众号，下面我们也会解析我们如何给公众号实现接入 FastWiki 的！

给 `FastWiki` 实现接入微信公众号

在FastWiki.Service项目中的Service目录创建 WeChatService 用于实现微信公众号接入功能，具体代码如下，

由于微信公众号的限制，没有实现微信公众号的微信认证，您的公众号是无法主动向用户发送信息，并且你的接口必须在5s内回复用户的信息，还得是xml格式（非常想吐槽！！！），在其中，我们将用户对话和AI回复使用Channel去分离我们的业务， AI通过读取Channel的对话信息，然后进行提问，并且调用了知识库服务提供的接口，还可以在知识库搜索相关prompt信息，然后得到大模型响应的内容，然后将响应的内容添加到内存缓存中，并且设置过期时间（防止用户提问以后不在继续造成内存溢出），然后当用户发送 1 提取AI的回复的时候获取内存的响应内容，然后直接返回给用户，然后删除内存缓存中的数据，这样就避免接口超过5s导致接口响应异常!

以下代码是微信公众号用于验证接口是否可用！

if (context.Request.Method != "POST") { context.Request.Query.TryGetValue("signature", outvar signature); context.Request.Query.TryGetValue("timestamp", outvar timestamp); context.Request.Query.TryGetValue("nonce", outvar nonce); context.Request.Query.TryGetValue("echostr", outvar echostr); await context.Response.WriteAsync(echostr); return; }

WeChatService具体实现

///<summary> /// 微信服务 ///</summary> public classWeChatService { staticWeChatService() { Task.Run(AIChatAsync); } privatestaticreadonly Channel<WeChatAI> Channel = System.Threading.Channels.Channel.CreateUnbounded<WeChatAI>(); privateconststring OutputTemplate = """ 您好，欢迎关注FastWiki！由于微信限制，我们无法立即回复您的消息，但是您的消息已经收到，我们会尽快回复您！如果获取消息结果，请输入1。如果您有其他问题，可以直接回复，我们会尽快回复您！ """; publicstaticasync Task AIChatAsync() { usingvar scope = MasaApp.RootServiceProvider.CreateScope(); var eventBus = scope.ServiceProvider.GetRequiredService<IEventBus>(); var wikiMemoryService = scope.ServiceProvider.GetRequiredService<WikiMemoryService>(); var memoryCache = scope.ServiceProvider.GetRequiredService<IMemoryCache>(); while (await Channel.Reader.WaitToReadAsync()) { var content = await Channel.Reader.ReadAsync(); await SendMessageAsync(content, eventBus, wikiMemoryService, memoryCache); } } ///<summary> /// 微信AI对话 ///</summary> ///<param name="chatAi"></param> ///<param name="eventBus"></param> ///<param name="wikiMemoryService"></param> ///<param name="memoryCache"></param> publicstaticasync Task SendMessageAsync(WeChatAI chatAi, IEventBus eventBus, WikiMemoryService wikiMemoryService, IMemoryCache memoryCache) { var chatShareInfoQuery = new ChatShareInfoQuery(chatAi.SharedId); await eventBus.PublishAsync(chatShareInfoQuery); // 如果chatShareId不存在则返回让下面扣款 var chatShare = chatShareInfoQuery.Result; var chatApplicationQuery = new ChatApplicationInfoQuery(chatShareInfoQuery.Result.ChatApplicationId); await eventBus.PublishAsync(chatApplicationQuery); var chatApplication = chatApplicationQuery?.Result; if (chatApplication == null) { return; } int requestToken = 0; var module = new ChatCompletionDto<ChatCompletionRequestMessage>() { messages = [ new() { content = chatAi.Content, role = "user", } ] }; var chatHistory = new ChatHistory(); // 如果设置了Prompt，则添加 if (!chatApplication.Prompt.IsNullOrEmpty()) { chatHistory.AddSystemMessage(chatApplication.Prompt); } // 保存对话提问 var createChatRecordCommand = new CreateChatRecordCommand(chatApplication.Id, chatAi.Content); await eventBus.PublishAsync(createChatRecordCommand); var sourceFile = new List<FileStorage>(); var memoryServerless = wikiMemoryService.CreateMemoryServerless(chatApplication.ChatModel); // 如果为空则不使用知识库 if (chatApplication.WikiIds.Count != 0) { var success = await OpenAIService.WikiPrompt(chatApplication, memoryServerless, chatAi.Content, eventBus, sourceFile, module); if (!success) { return; } } var output = new StringBuilder(); // 添加用户输入，并且计算请求token数量 module.messages.ForEach(x => { if (x.content.IsNullOrEmpty()) return; requestToken += TokenHelper.ComputeToken(x.content); chatHistory.Add(new ChatMessageContent(new AuthorRole(x.role), x.content)); }); if (chatShare != null) { // 如果token不足则返回，使用token和当前request总和大于可用token，则返回 if (chatShare.AvailableToken != -1 && (chatShare.UsedToken + requestToken) >= chatShare.AvailableToken) { output.Append("Token不足"); return; } // 如果没有过期则继续 if (chatShare.Expires != null && chatShare.Expires < DateTimeOffset.Now) { output.Append("Token已过期"); return; } } try { awaitforeach (var item in OpenAIService.SendChatMessageAsync(chatApplication, eventBus, wikiMemoryService, chatHistory)) { if (string.IsNullOrEmpty(item)) { continue; } output.Append(item); } //对于对话扣款 if (chatShare != null) { var updateChatShareCommand = new DeductTokenCommand(chatShare.Id, requestToken); await eventBus.PublishAsync(updateChatShareCommand); } } catch (NotModelException notModelException) { output.Clear(); output.Append(notModelException.Message); } catch (InvalidOperationException invalidOperationException) { output.Clear(); output.Append("对话异常:" + invalidOperationException.Message); } catch (ArgumentException argumentException) { output.Clear(); output.Append("对话异常:" + argumentException.Message); } catch (Exception e) { output.Clear(); output.Append("对话异常,请联系管理员"); } finally { memoryCache.Set(chatAi.MessageId, output.ToString(), TimeSpan.FromMinutes(5)); } } ///<summary> /// 接收消息 ///</summary> ///<param name="context"></param> publicstaticasync Task ReceiveMessageAsync(HttpContext context, string? id, IMemoryCache memoryCache) { if (context.Request.Method != "POST") { context.Request.Query.TryGetValue("signature", outvar signature); context.Request.Query.TryGetValue("timestamp", outvar timestamp); context.Request.Query.TryGetValue("nonce", outvar nonce); context.Request.Query.TryGetValue("echostr", outvar echostr); await context.Response.WriteAsync(echostr); return; } usingvar reader = new StreamReader(context.Request.Body); // xml解析 var body = await reader.ReadToEndAsync(); var doc = new XmlDocument(); doc.LoadXml(body); var root = doc.DocumentElement; var input = new WeChatMessageInput { ToUserName = root.SelectSingleNode("ToUserName")?.InnerText, FromUserName = root.SelectSingleNode("FromUserName")?.InnerText, CreateTime = long.Parse(root.SelectSingleNode("CreateTime")?.InnerText ?? "0"), MsgType = root.SelectSingleNode("MsgType")?.InnerText, Content = root.SelectSingleNode("Content")?.InnerText, MsgId = long.Parse(root.SelectSingleNode("MsgId")?.InnerText ?? "0") }; var output = new WehCahtMe { ToUserName = input.ToUserName, FromUserName = input.FromUserName, CreateTime = input.CreateTime, MsgType = input.MsgType, Content = input.Content }; if (output.Content.IsNullOrEmpty()) { return; } if (id == null) { context.Response.ContentType = "application/xml"; await context.Response.WriteAsync(GetOutputXml(output, "参数错误，请联系管理员！code:id_null")); return; } var messageId = GetMessageId(output); // 从缓存中获取,如果有则返回 memoryCache.TryGetValue(messageId, outvarvalue); // 如果value有值则，但是value为空，则返回提示,防止重复提问！ if (valueisstring str && str.IsNullOrEmpty()) { context.Response.ContentType = "application/xml"; await context.Response.WriteAsync(GetOutputXml(output, "暂无消息，请稍后再试！code:no_message")); return; } elseif (valueisstring v && !v.IsNullOrEmpty()) { context.Response.ContentType = "application/xml"; await context.Response.WriteAsync(GetOutputXml(output, v)); return; } if (output.Content == "1") { if (valueisstring v && !v.IsNullOrEmpty()) { memoryCache.Remove(messageId); context.Response.ContentType = "application/xml"; await context.Response.WriteAsync(GetOutputXml(output, v)); return; } context.Response.ContentType = "application/xml"; await context.Response.WriteAsync(GetOutputXml(output, "暂无消息，请稍后再试！code:no_message")); return; } // 先写入channel，等待后续处理 Channel.Writer.TryWrite(new WeChatAI() { Content = output.Content, SharedId = id, MessageId = messageId }); // 等待4s await Task.Delay(4500); // 尝试从缓存中获取 memoryCache.TryGetValue(messageId, outvar outputTemplate); if (outputTemplate isstring outValue && !outValue.IsNullOrEmpty()) { context.Response.ContentType = "application/xml"; await context.Response.WriteAsync(GetOutputXml(output, outValue)); return; } context.Response.ContentType = "application/xml"; await context.Response.WriteAsync(GetOutputXml(output, OutputTemplate)); // 写入缓存,5分钟过期 memoryCache.Set(messageId, OutputTemplate, TimeSpan.FromMinutes(5)); } privatestaticstringGetMessageId(WehCahtMe output) { return output.FromUserName + output.ToUserName; } ///<summary> /// 获取返回的xml ///</summary> ///<param name="output"></param> ///<param name="content"></param> ///<returns></returns> publicstaticstringGetOutputXml(WehCahtMe output, string content) { var createTime = DateTimeOffset.Now.ToUnixTimeSeconds(); var xml = $@" <xml> <ToUserName><![CDATA[{output.FromUserName}]]></ToUserName> <FromUserName><![CDATA[{output.ToUserName}]]></FromUserName> <CreateTime>{createTime}</CreateTime> <MsgType><![CDATA[text]]></MsgType> <Content><![CDATA[{content}]]></Content> </xml> "; return xml; } public classWeChatMessageInput { publicstring URL { get; set; } publicstring ToUserName { get; set; } publicstring FromUserName { get; set; } publiclong CreateTime { get; set; } publicstring MsgType { get; set; } publicstring Content { get; set; } publiclong MsgId { get; set; } } public classWehCahtMe { publicstring ToUserName { get; set; } publicstring FromUserName { get; set; } publiclong CreateTime { get; set; } publicstring MsgType { get; set; } publicstring Content { get; set; } } }

WeChat提供的API服务

上面是接口的具体实现，然后我们在 Program 中将我们的 WeChatService 对外提供API（Get是用于提供给微信公众号验证）， {id} 则绑定我们的接口的 string id 参数，以便动态设置。

app.MapGet("/api/v1/WeChatService/ReceiveMessage/{id}", WeChatService.ReceiveMessageAsync) .WithTags("WeChat") .WithGroupName("WeChat") .WithDescription("微信消息验证") .WithOpenApi(); app.MapPost("/api/v1/WeChatService/ReceiveMessage/{id}", WeChatService.ReceiveMessageAsync) .WithTags("WeChat") .WithGroupName("WeChat") .WithDescription("微信消息接收") .WithOpenApi();