意图处理程序失败并出现错误：未定义缓冲区

Question

我使用 Local Fulfillment SDK 构建了一个 Google Smart Home Action，如以下文章所述：

• https://developers.google.com/assistant/smarthome/develop/local
• https://github.com/actions-on-google/create-local-home-app

我正在使用 UDP 进行设备发现，我的 Google Nest Hub 可以成功扫描和检测在我的笔记本电脑上运行的虚拟设备以及下载本地应用程序的 JS。

我的Local Home SDK配置如下-Local Home SDK Configuration。

当 Nest Hub 执行我的应用处理程序的 IDENTIFY 意图时，我收到以下错误：

[smarthome.DeviceManager] Intent handler failed with error: Buffer is not defined

[smarthome.DeviceManager] Got a rejected promise Buffer is not defined 

这似乎是一个 Node.JS 错误，而不是特定于本地 SDK 应用程序本身的错误。下面是我本地应用的代码。

/// <reference types="@google/local-home-sdk" />

import App = smarthome.App;
import Constants = smarthome.Constants;
import DataFlow = smarthome.DataFlow;
import Execute = smarthome.Execute;
import Intents = smarthome.Intents;
import IntentFlow = smarthome.IntentFlow;

const SERVER_PORT = 3388;

interface ILightParams {
  on?: boolean,
  brightness?: number
}

class LocalExecutionApp {

  constructor(private readonly app: App) { }

  identifyHandler(request: IntentFlow.IdentifyRequest):
      Promise<IntentFlow.IdentifyResponse> {
    console.log("IDENTIFY intent: " + JSON.stringify(request, null, 2));

    const scanData = request.inputs[0].payload.device.udpScanData;
    console.log("SCANDATA: " + JSON.stringify(scanData));
    if (!scanData) {
      const err = new IntentFlow.HandlerError(request.requestId, 'invalid_request', 'Invalid scan data');
      return Promise.reject(err);
    }

    const localDeviceId = Buffer.from(scanData.data, 'hex');
    console.log("ScanData Local Device: " + localDeviceId);

    const response: IntentFlow.IdentifyResponse = {
      intent: Intents.IDENTIFY,
      requestId: request.requestId,
      payload: {
        device: {
          // id: localDeviceId.toString(),
          id: 'sample-device',
          verificationId: localDeviceId.toString(),
        }
      }
    };
    console.log("IDENTIFY response: " + JSON.stringify(response, null, 2));

    return Promise.resolve(response);
  }

  executeHandler(request: IntentFlow.ExecuteRequest):
      Promise<IntentFlow.ExecuteResponse> {
    console.log("EXECUTE intent: " + JSON.stringify(request, null, 2));

    const command = request.inputs[0].payload.commands[0];
    const execution = command.execution[0];
    const response = new Execute.Response.Builder()
      .setRequestId(request.requestId);

    const promises: Promise<void>[] = command.devices.map((device) => {
      console.log("Handling EXECUTE intent for device: " + JSON.stringify(device));

      // Convert execution params to a string for the local device
      const params = execution.params as ILightParams;
      const payload = this.getDataForCommand(execution.command, params);

      // Create a command to send over the local network
      const radioCommand = new DataFlow.HttpRequestData();
      radioCommand.requestId = request.requestId;
      radioCommand.deviceId = device.id;
      radioCommand.data = JSON.stringify(payload);
      radioCommand.dataType = 'application/json';
      radioCommand.port = SERVER_PORT;
      radioCommand.method = Constants.HttpOperation.POST;
      radioCommand.isSecure = false;

      console.log("Sending HTTP request to the smart home device:", payload);

      return this.app.getDeviceManager()
        .send(radioCommand)
        .then(() => {
          const state = {online: true};
          response.setSuccessState(device.id, Object.assign(state, params));
          console.log(`Command successfully sent to ${device.id}`);
        })
        .catch((e: IntentFlow.HandlerError) => {
          e.errorCode = e.errorCode || 'invalid_request';
          response.setErrorState(device.id, e.errorCode);
          console.error('An error occurred sending the command', e.errorCode);
        });
    });

    return Promise.all(promises)
      .then(() => {
        return response.build();
      })
      .catch((e) => {
        const err = new IntentFlow.HandlerError(request.requestId, 'invalid_request', e.message);
        return Promise.reject(err);
      });
  }

  /**
   * Convert execution request into a local device command
   */
  getDataForCommand(command: string, params: ILightParams): unknown {
    switch (command) {
      case 'action.devices.commands.OnOff':
        return {
          on: params.on ? true : false
        };
      default:
        console.error('Unknown command', command);
        return {};
    }
  }
}

const localHomeSdk = new App('1.0.0');
const localApp = new LocalExecutionApp(localHomeSdk);
localHomeSdk
  .onIdentify(localApp.identifyHandler.bind(localApp))
  .onExecute(localApp.executeHandler.bind(localApp))
  .listen()
  .then(() => console.log('Ready'))
  .catch((e: Error) => console.error(e));

非常感谢任何有关此错误发生原因的见解。

干杯。

Answer 1

在 cmets 中转发答案：

Buffer 不是浏览器环境直接支持的类型。您可以通过尝试在 Web 浏览器的开发控制台中运行类似 x = new Buffer() 的内容来亲眼看到这一点。

要支持像 Buffer 这样的类，您可以使用像 Webpack 这样的捆绑工具。在官方示例中，您可以看到example Webpack configuration。也可以使用其他捆绑工具，示例可以在official Local Home scaffolding tool 中找到，也可以通过npm init 命令直接调用。

npm init @google/local-home-app app/ --bundler webpack
npm init @google/local-home-app app/ --bundler rollup
npm init @google/local-home-app app/ --bundler parcel