node.js - 名为 '[DEFAULT]' 的 Firebase 应用程序已经存在，并且 google firebase 引用在服务器上不起作用

Question

我遵循了 https://firebase.google.com/docs/database/server/retrieve-data#section-start 中服务器配置的所有步骤，但是当我尝试在浏览器中创建引用时，告诉我名为 [default] 的应用程序已经存在。那时如果 preiono F5 然后告诉我有“databaseUrl”，我必须确保在启动应用程序 firebase 时提供该数据。

var express = require('express');
var router = express.Router();

var firebase = require('firebase');

/* GET home page. */
router.get('/', function(req, res, next) {

  firebase.initializeApp({
    serviceAccount: "aaaabbbbcccc.json",
    databaseUrl: "https://xxxxxyyyyyzzzzz.firebaseio.com/" // <<<<--- it can not find
  });

  var db = firebase.database();   // <<<<---- Here is a problem
  var ref = db.ref('vistas/principal');
  ref.once('value', function(data){

    res.render('index', { title: 'Express' });

  });


});

module.exports = router;

我创建了其他授权、其他 key 等。但没有任何效果。谢谢。

Node -v = v4.2.6Firebase v3.x

FIREBASE FATAL ERROR: Can't determine Firebase Database URL. Be sure to include databaseURL option when calling firebase.intializeApp().

Error: FIREBASE FATAL ERROR: Can't determine Firebase Database URL.  Be sure to include databaseURL option when calling firebase.intializeApp(). 
    at Error (native)
    at ad (c:\TsPrj\_pruebas\vistas-realtime-desde-firebase\node_modules\firebase\database-node.js:37:278)
    at Object.firebase.INTERNAL.registerService.Reference [as database] (c:\TsPrj\_pruebas\vistas-realtime-desde-firebase\node_modules\firebase\database-node.js:238:113)
    at O.u (c:\TsPrj\_pruebas\vistas-realtime-desde-firebase\node_modules\firebase\app-node.js:16:94)
    at Object.d [as database] (c:\TsPrj\_pruebas\vistas-realtime-desde-firebase\node_modules\firebase\app-node.js:18:182)
    at c:\TsPrj\_pruebas\vistas-realtime-desde-firebase\routes\index.js:14:21
    at Layer.handle [as handle_request] (c:\TsPrj\_pruebas\vistas-realtime-desde-firebase\node_modules\express\lib\router\layer.js:95:5)
    at next (c:\TsPrj\_pruebas\vistas-realtime-desde-firebase\node_modules\express\lib\router\route.js:131:13)
    at Route.dispatch (c:\TsPrj\_pruebas\vistas-realtime-desde-firebase\node_modules\express\lib\router\route.js:112:3)
    at Layer.handle [as handle_request] (c:\TsPrj\_pruebas\vistas-realtime-desde-firebase\node_modules\express\lib\router\layer.js:95:5)

Answer 1

您可以检查应用程序是否已经加载，因为它应该加载一次。一种方法是:

if (!firebase.apps.length) {
    firebase.initializeApp({});
}