我一直在嘗試Cloud Messaging為我的應用程序實施，以便應用程序的每個用戶在添加新孩子時都會自動收到通知Realtime Database.在我的文章中，MainActivity我使用此方法為每個用戶訂閱一個主題。FirebaseMessaging.getInstance().subscribeToTopic("latest_events").addOnSuccessListener(new OnSuccessListener<Void>() { @Override public void onSuccess(Void aVoid) { // Toast.makeText(MainActivity.this, "Successfully subscribed", Toast.LENGTH_SHORT).show(); } });我還firebase functions為我的后端安裝并部署了我的 javascript 代碼。索引.jsvar functions = require('firebase-functions');const admin = require('firebase-admin');admin.initializeApp(functions.config().firebase);exports.sendNotification = functions.database.ref("/Users").onWrite(event => { var payload = { notification: { title: "A new user has been added!", body: "Click to see" } }; if (event.data.previous.exists()) { if (event.data.previous.numChildren() < event.data.numChildren()) { return admin.messaging().sendToTopic("latest_events", payload); } else { return; } } if (!event.data.exists()) { return; } return admin.messaging().sendToTopic("latest_events", payload);});添加用戶時，我沒有收到所需的通知。似乎無法理解我做錯了什么。Firebase 函數(shù)日志 CatsendNotificationTypeError: Cannot read property 'previous' of undefined at exports.sendNotification.functions.database.ref.onWrite.event (/user_code/index.js:15:19) at cloudFunctionNewSignature (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:105:23) at cloudFunction (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:135:20) at /var/tmp/worker/worker.js:730:24 at process._tickDomainCallback (internal/process/next_tick.js:135:7)
1 回答
長風秋雁
TA貢獻1757條經(jīng)驗 獲得超7個贊
您使用的是 Cloud Functions for Firebase 測試版中的語法。由于它已更新到 1.0，因此語法發(fā)生了變化，您需要更新代碼以匹配升級文檔中所述。
將其應用于您的代碼會導致如下結果：
var functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();
exports.sendNotification = functions.database.ref("/Users").onWrite((change, context) => {
var payload = {
notification: {
title: "A new user has been added!",
body: "Click to see"
}
};
if (change.before.exists()) {
if (change.before.numChildren() < change.after.numChildren()) {
return admin.messaging().sendToTopic("latest_events", payload);
} else {
return;
}
}
if (!change.after.exists()) {
return;
}
return admin.messaging().sendToTopic("latest_events", payload);
});
變化是：
有兩個參數(shù)傳遞到函數(shù)中，而以前只有一個。
您不再需要將配置傳遞到initializeApp.
在before和after快照現(xiàn)在可從change。
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