javascript - 如何修复云函数错误 admin.database.ref 不是导出时的函数

Question

我目前正在尝试修改我的 Cloud Functions 并移至 https.onRequest 下这样我就可以调用它来安排 cron 作业。我如何在日志中收到以下错误。

TypeError: admin.database.ref is not a function at exports.scheduleSendNotificationMessageJob.functions.https.onRequest (/user_code/index.js:30:20) at cloudFunction (/user_code/node_modules/firebase-functions/lib/providers/https.js:57:9)

exports.scheduleSendNotificationMessageJob = functions.https.onRequest((req, res) => {
    admin.database.ref('/notifications/{studentId}/notifications/{notificationCode}')
        .onCreate((dataSnapshot, context) => {
            const dbPath = '/notifications/' + context.params.pHumanId + '/fcmCode';
            const promise = admin.database().ref(dbPath).once('value').then(function(tokenSnapshot) {
                const theToken = tokenSnapshot.val();
                res.status(200).send(theToken);
                const notificationCode = context.params.pNotificationCode;
                const messageData = {notificationCode: notificationCode};
                const theMessage = {    data: messageData,
                    notification: { title: 'You have a new job reminder' }
                };
                const options = {   contentAvailable: true,
                    collapseKey: notificationCode };
                const notificationPath = '/notifications/' + context.params.pHumanId + '/notifications/' + notificationCode;
                admin.database().ref(notificationPath).remove();
                return admin.messaging().sendToDevice(theToken, theMessage, options);
            });
            return null;
        });
});

Answer 1

您不能在 HTTP 云函数的定义内使用 onCreate() 实时数据库触发器的定义。

如果您切换到 HTTP 云函数“以便(您)可以调用它来安排 cron 作业”，则意味着触发器将是对 HTTP 云函数的调用。换句话说，当实时数据库中创建新数据时，您将无法再触发操作(或云函数)。

你可以很好地做的是读取实时数据库的数据，例如如下(发送通知的简化场景):

exports.scheduleSendNotificationMessageJob = functions.https.onRequest((req, res) => {

    //get the desired values from the request
    const studentId = req.body.studentId;
    const notificationCode = req.body.notificationCode;

    //Read data with the once() method
    admin.database.ref('/notifications/' + studentId + '/notifications/' + notificationCode)
     .once('value')
     .then(snapshot => {
         //Here just an example on how you would get the desired values
         //for your notification
         const theToken = snapshot.val();
         const theMessage = ....
         //......

         // return the promise returned by the sendToDevice() asynchronous task
         return admin.messaging().sendToDevice(theToken, theMessage, options)
      })
      .then(() => {
         //And then send back the result (see video referred to below)
         res.send("{ result : 'message sent'}") ;
      })
      .catch(err => {
         //........
      });

});

您可以观看以下有关 HTTP Cloud Functions 的 Firebase 官方视频:https://www.youtube.com/watch?v=7IkUgCLr5oA&t=1s&list=PLl-K7zZEsYLkPZHe41m4jfAxUi0JjLgSM&index=3 。它展示了如何从 Firestore 读取数据，但读取和发回响应(或错误)的概念对于实时数据库是相同的。与该系列的另外 2 个视频 ( https://firebase.google.com/docs/functions/video-series/?authuser=0 ) 一起，它还解释了正确链接 promise 并向平台表明云功能的工作已完成的重要性。