ReferenceError：值未定义CloudFunction

Question

–尝试向设备在Firebase数据库中拥有的所有用户发送通知，但在云函数的寄存器中显示：“ ReferenceError：未定义值”。

应该做的是：每次在“通知”中进行更改时，您都必须获取已更改的数据，并在设备表中查找此数据，并将通知发送到该设备中的所有令牌。

这是错误：

cloudfunction的代码：

const functions = require('firebase-functions');
const admin = require('firebase-admin');  // this is the Admin SDK, not firebase-functions

admin.initializeApp(functions.config().firebase);

const db = admin.database()
const ms = admin.messaging()

exports.notifications = functions.database.ref('Notifications/{id}').onUpdate(async(evt) =>{

const payload = {
    notification:{
        title   : 'Alarma se activó tu cerca',
        body    : 'Se activó tu cerca, revisala',
        badge   : '1',
        sound   :'defaul'   
    }
};

//Get Notification Device ID
const notySnap = await db.ref('Notification/').once('value');

var devicee = notySnap.notty;
var dev = JSON.stringify(devicee);

//Get number of users that the device had
const usersSnap = await db.ref('Devices/'+ dev + '/Users').once(value)
const nUsers = usersSnap.nUsers;
var Nusers = JSON.stringify(nUsers);
var nNUsers = parseInt(Nusers);

//Send notification to the number of users that exist
if (Nusers !== null){
    for(i = 1; 1 <=nNUsers; i++){
        if(i === 1){
            const userToSendP1 = usersSnap.user1;
            var userToSend1 = JSON.stringify(userToSendP1);
            Console.log("Mensaje enviado a user 1");
            return ms.sendToDevice(userToSend1, payload);
        }else if(i === 2){
            const userToSendP2 = usersSnap.user2;
            var userToSend2 = JSON.stringify(userToSendP2);
            Console.log("Mensaje enviado a user 2");
            return ms.sendToDevice(userToSend2, payload);
        }else if(i === 2){
            const userToSendP3 = usersSnap.user3;
            var userToSend3 = JSON.stringify(userToSendP3);
            Console.log("Mensaje enviado a user 3");
            return ms.sendToDevice(userToSend3, payload);
        }else if(i === 2){
            const userToSendP4 = usersSnap.user4;
            var userToSend4 = JSON.stringify(userToSendP4);
            Console.log("Mensaje enviado a user 4");
            return ms.sendToDevice(userToSend4, payload);
        }
    }
}
return null
})

数据库：

Answer 1

在此行：

const usersSnap = await db.ref('Devices/'+ dev + '/Users').once(value)

value是您从未定义的变量。这就是错误消息的含义。您可能是用'value'作为字符串来代替的：

const usersSnap = await db.ref('Devices/'+ dev + '/Users').once('value')