获取快照值的"Undefined"

Question

日志结果

日志错误的内部我目前正在设置Firebase Cloud功能，以使用户每次添加一个新的孩子在"消息"中添加新的孩子。对于每个用户，在此结构"/user/uid/doken"中的节点中都有一个通知。但是，在我在火箱控制台中的日志中，返回的值是"未定义"的。这是我第一次使用node.js，所以一切都非常新。任何帮助，将不胜感激。这是功能内部的内容

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
// Listens for new messages added to messages/:pushId
exports.messageWritten =     functions.database.ref('/messages/{pushId}').onWrite( event => {
console.log('Push notification event triggered');
//  Grab the current value of what was written to the Realtime   Database.
var valueObject = event.data.val();
console.log(valueObject.text,valueObject.toId);
return admin.database().ref(`/Users/${valueObject.toId}`).once('value').then(snapshot =>{
    console.log('the users name',snapshot.name)
    console.log('the users token',snapshot.token)
})

// Create a notification
const payload = {
    notification: {
        title:snapshot.name +' sent you a message', 
        body: valueObject.text,
        sound: "default"
    },
};
 //Create an options object that contains the time to live for the  notification and the priority
const options = {
    priority: "high",
    timeToLive: 60 * 60 * 24
};

  return admin.messaging().sendToDevice(snapshot.token, payload, options);
});

Answer 1

您的功能中有两个return语句。第一个返回语句(发送消息(之后的代码将不会运行。

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
// Listens for new messages added to messages/:pushId
exports.messageWritten = functions.database.ref('/messages/{pushId}').onWrite(event => {
    console.log('Push notification event triggered');
    //  Grab the current value of what was written to the Realtime   Database.
    var valueObject = event.data.val();
    console.log(valueObject.text, valueObject.toId);
    return admin.database().ref(`/Users/${valueObject.toId}`).once('value').then(snapshot => {
        console.log('the users name', snapshot.val().name)
        console.log('the users token', snapshot.val().token)
        // Create a notification
        const payload = {
            notification: {
                title: snapshot.val().name + ' sent you a message',
                body: valueObject.text,
                sound: "default"
            },
        };
        //Create an options object that contains the time to live for the  notification and the priority
        const options = {
            priority: "high",
            timeToLive: 60 * 60 * 24
        };
        return admin.messaging().sendToDevice(snapshot.val().token, payload, options);
    })
});