Question

我正在为学生设计游戏体验。游戏就像是危险的游戏，随着学生在游戏中的进步，它会将数据写入实时数据库。在游戏结束时，我想向学生发送电子邮件，确认他们的分数和完成时间/日期已经完成。

我已经在云函数中设置了以下代码。但是，当我从触发器中运行代码时，我从数据库读取的某些值显示为未定义-这意味着电子邮件中不存在某些数据。这里发生了什么？？？

   'use strict';

    const functions = require('firebase-functions');
    const admin = require('firebase-admin');
    const nodemailer = require('nodemailer');

    admin.initializeApp({
       credential: admin.credential.applicationDefault(),
       databaseURL: 'https://[MY DATABASE URL]/'
    });

     const gmailEmail = functions.config().gmail.email;
     const gmailPassword = functions.config().gmail.password;
     const mailTransport = nodemailer.createTransport({
        service: 'gmail',
        auth: {
           user: gmailEmail,
           pass: gmailPassword,
         },
       });       

         var email;
         var exitTime;
         var name;
         var userScore;

 exports.gameDoneNotice=functions.database.ref("USERS/{termDate}/GameData/{myUID}/ExitDateTime")
  .onCreate(async (snapshot, context) => {

         const myNumber = context.params.myUID; 
         const myRotation = context.params.termDate; 

            var adminDB = admin.database();

            exitTime = snapshot.val();

            var aRef = adminDB.ref("USERS/" + myRotation + "/GameData/" + myNumber + "/");
            aRef.on("value", (snapshot) => {
                email = snapshot.child("eMail").val();
                name = snapshot.child("Name").val();
                userScore = snapshot.child("User Score").val();
            });

            var emailsaad = "MYEMAIL@EMAIL.COM";

            console.log(myNumber);
            console.log(myRotation);
            console.log(userScore);
            console.log(name); 


        const APP_NAME = 'WCM-Q DeLib eLearning';        

        const mailOptions = {
             from: `${APP_NAME} <noreply@firebase.com>`,
             to: email,
             bcc: emailsaad,
            };  


         mailOptions.subject = `Welcome to ${APP_NAME}!`;
         mailOptions.html = `<h3>Dear, ${name}</h3><p>Thank you for completing the Medicine Clerkship EBM game.</p><hr><h4>Your Score: <font color="red">${userScore}</font></h4><h4>Game Completion  Time/Date: <font color="green">${exitTime}</font></h4><hr><p>If you have any questions about the game or your EBM project in this clerkship, don’t hesitate to ask for clarification. Otherwise, your next step is to begin to prepare with your group for your presentation.</p>`;


         try {
             await mailTransport.sendMail(mailOptions);
             console.log("eMail was a success");
           } catch(error) {
             console.error('Something has gone horribly wrong, bro!', error);
           }
            return null;

            });

我希望我应该能够从数据库中读取电子邮件，userScore等所需的值，并将其包含在mailOptions中，然后再发送。但是，当我在触发器之后收到电子邮件时，从数据库读取的所有值都是“未定义的”。

Answer 1

您无需使用on()方法，该方法将监听程序“特定位置的数据更改”设置为监听器，而是使用once()方法，该方法仅侦听指定位置的一个事件。事件类型”，并返回承诺。然后，您将能够使用await来使Cloud Function等待，直到once()返回的承诺解析并返回其结果。

因此，您应该按以下方式修改代码：

exports.gameDoneNotice = functions.database
  .ref('USERS/{termDate}/GameData/{myUID}/ExitDateTime')
  .onCreate(async (snapshot, context) => {
    const myNumber = context.params.myUID;
    const myRotation = context.params.termDate;

    var adminDB = admin.database();

    exitTime = snapshot.val();

    var aRef = adminDB.ref(
      'USERS/' + myRotation + '/GameData/' + myNumber + '/'
    );

    try {
      const snapshot = await aRef.once('value');
      const email = snapshot.child('eMail').val();
      const name = snapshot.child('Name').val();
      const userScore = snapshot.child('User Score').val();

      const emailsaad = 'MYEMAIL@EMAIL.COM';

      console.log(myNumber);
      console.log(myRotation);
      console.log(userScore);
      console.log(name);

      const APP_NAME = 'WCM-Q DeLib eLearning';

      const mailOptions = {
        from: `${APP_NAME} <noreply@firebase.com>`,
        to: email,
        bcc: emailsaad
      };

      mailOptions.subject = `Welcome to ${APP_NAME}!`;
      mailOptions.html = `<h3>Dear, ${name}</h3><p>Thank you for completing the Medicine Clerkship EBM game.</p><hr><h4>Your Score: <font color="red">${userScore}</font></h4><h4>Game Completion  Time/Date: <font color="green">${exitTime}</font></h4><hr><p>If you have any questions about the game or your EBM project in this clerkship, don’t hesitate to ask for clarification. Otherwise, your next step is to begin to prepare with your group for your presentation.</p>`;

      await mailTransport.sendMail(mailOptions);
      //Here, actually you could also do return mailTransport.sendMail(mailOptions); , see the video mentioned below

    } catch (error) {
      console.error('Something has gone horribly wrong, bro!', error);
    }
  });

您可以观看道格·史蒂文森（Doug Stevenson）的官方Firebase video series，其中解释了所有这些要点。特别是有关“ JavaScript Promises”的3个视频和有关async / await的视频：https://www.youtube.com/watch?v=Jr7pDZ1RAUg

Firebase云功能错误：一些值显示为未定义？

1 个答案: