如何在Lambda函数中定义emit（）属性

Question

我只是想让Alexa说出谷歌电子表格中的数据。我正在使用google-spreadsheet node.js模块而不是http.get（）方法。

这是我的意图功能

'GetPainterIntent': function() {
        // spreadsheet key is the long id in the sheets URL 
var doc = new GoogleSpreadsheet('1K-dl08g8s27TgF5yMGv_Q5tBbkpRpGWrt3RkUB2mVKk');
var sheet;

async.series([
  function setAuth(step) {
    // see notes below for authentication instructions! 
    var creds = require('./creds.json');
    // OR, if you cannot save the file locally (like on heroku) 
    /*
    var creds_json = {
      client_email: ' ',
      private_key: ' '
    }
        */
    doc.useServiceAccountAuth(creds, step);

  },
  function getInfoAndWorksheets(step) {

    doc.getInfo(function(err, info) {
      console.log('Loaded doc: '+info.title+' by '+info.author.email);
      sheet = info.worksheets[0];

      //console.log('sheet 1: '+sheet.title+' '+sheet.rowCount+'x'+sheet.colCount);
      this.emit('ask:', 'Do you want'+sheet.title+' '+sheet.rowCount+'x'+sheet.colCount);
      step();
    });

  }

], function(err){
    if( err ) {
      console.log('Error: '+err);
    }
});

    } 

在执行结果中：失败的日志，我得到的一个关键事项是......

 {
 "errorMessage": "RequestId: 79ed1bc9-aaee-11e7-878b-5fe3ebd777ae 
 Process 
 exited before completing request"
 }

TypeError: Cannot read property 'emit' of undefined
at getInfoAndWorksheets (/var/task/index.js:51:9)
at /var/task/node_modules/async/dist/async.js:3853:24
at replenish (/var/task/node_modules/async/dist/async.js:946:17)
at iterateeCallback

emit内的属性是否未定义？或者你如何定义发射的属性或我读错了吗？

Answer 1

我认为问题在于你以编码的方式丢失了this，可能是因为它使用异步系列。用this这样的线保存var self=this，然后用self.emit代替。