Question

我正在使用firebase云功能来监听数据库值事件，这是我的代码

    var functions = require('firebase-functions');
var firebase = require('firebase-admin');

var serviceAccount = require("./serviceAccountKey.json");

firebase.initializeApp({
    credential : firebase.credential.cert(serviceAccount),
    databaseURL: "https://*******.firebaseio.com"
});

exports.notifications = functions.database.ref('/chat/{senderID}/{destinationID}/messages/{pushID}')
    .onWrite(event => {        
        var eventSnapshot = event.data;        
        var sender = eventSnapshot.child('sender').val();
        var message = eventSnapshot.child('message').val();
        var destination = eventSnapshot.child('destination').val();        
        if (event.params.senderID === sender) 
            sendMessage(message,sender,destination);    
    }
);

function sendMessage(message, sender, destination) {

    var senderUser = firebase.database().ref('users/'+sender+'/name'); 
    var tokenUser = firebase.database().ref('fcm/'+destination+'/token');
        tokenUser.once('value').then(function(tokenSnapshot) {
            var token = tokenSnapshot.val(); 
                        console.log(token);                        

    }, function (errorObject) {
  console.log("The read failed: " + errorObject.code);
});     
}

onWrite函数正常执行，但tokenUser.once()未执行。

Answer 1

也许如果您尝试使用tokenUser.once('value')并且不传递函数，并直接获取tokenSnapshot;像这样的东西：

tokenUser.once('value').then(tokenSnapshot => {
        var token = tokenSnapshot.val(); 
        console.log(token);                        

});

如果您使用tokenUser.once()进行回调，则可以传递该功能;像这样的东西：

tokenUser.once('value', function(tokenSnapshot) {
        var token = tokenSnapshot.val(); 
                    console.log(token);                        

}, function (errorObject) {
  console.log("The read failed: " + errorObject.code);
});

无法从firebase数据库中检索数据（云功能）

1 个答案: