问如何在云消息传递触发函数中引用Firebase实时数据(在标题或正文中使用)

EN

   {
  "movecarday" : "Monday",
  "movecartime" : "9:30",
}

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

exports.pushNotification = functions.database.ref('/movecarday/{day}').onWrite((change, context) => {
    console.log('Push notification event triggered');

    const valueObject = change.after.val(); 
    var thisistheday = valueObject;
    
var timeref = firebase.database().ref("/movecartime/{time}");
    timeref.on("value", function(snapshot) {
    var thisisthetime = snapshot.val();
});


    const payload = {
        notification: {
            title: `The car is parked in a ${thisistheday} spot!`,
            body: `Must be moved by ${thisisthetime}`,
            sound: "default"
        }
        }; 

 const options = {
        priority: "high",
        timeToLive: 60 * 60 * 24
    };

    return admin.messaging().sendToTopic("pushNotifications", payload, options);
});