I have a fully functional App on Android and IOS, and now I want to have a web version taking advantage of Flutter's cross-platform features.
To do this, I created a "Chrome Device" from VS Code and I did the Firebase App registration within the Firebase console. In the index.html I included the configuration as explained in Flutter Firebase Installation Web ...
<!DOCTYPE html>
<html>
<head>
<!--
If you are serving your web app in a path other than the root, change the
href value below to reflect the base path you are serving from.
The path provided below has to start and end with a slash "/" in order for
it to work correctly.
For more details:
* https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base
This is a placeholder for base href that will be replaced by the value of
the `--base-href` argument provided to `flutter build`.
-->
<base href="$FLUTTER_BASE_HREF">
<meta charset="UTF-8">
<meta content="IE=Edge" http-equiv="X-UA-Compatible">
<meta name="description" content="A new Flutter project.">
<!-- iOS meta tags & icons -->
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black">
<meta name="apple-mobile-web-app-title" content="appname">
<link rel="apple-touch-icon" href="icons/Icon-192.png">
<title>AppName</title>
<link rel="manifest" href="manifest.json">
</head>
<body>
<script src="https://www.gstatic.com/firebasejs/8.6.1/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/8.6.1/firebase-auth.js"></script>
<script src="https://www.gstatic.com/firebasejs/8.6.1/firebase-database.js"></script>
<script src="https://www.gstatic.com/firebasejs/8.6.1/firebase-messaging.js"></script>
<script>
// Your web app's Firebase configuration
// For Firebase JS SDK v7.20.0 and later, measurementId is optional
var firebaseConfig = {
apiKey: "xxx", //with my particular values
authDomain: "xxx",
databaseURL: "xxx",
projectId: "xxx",
storageBucket: "xxx",
messagingSenderId: "xxx",
appId: "xxx",
measurementId: "xxx"
};
// Initialize Firebase
firebase.initializeApp(firebaseConfig); //
</script>
<!-- This script installs service_worker.js to provide PWA functionality to
application. For more information, see:
https://developers.google.com/web/fundamentals/primers/service-workers -->
<script>
var serviceWorkerVersion = null;
var scriptLoaded = false;
function loadMainDartJs() {
if (scriptLoaded) {
return;
}
scriptLoaded = true;
var scriptTag = document.createElement('script');
scriptTag.src = 'main.dart.js';
scriptTag.type = 'application/javascript';
document.body.append(scriptTag);
}
if ('serviceWorker' in navigator) {
// Service workers are supported. Use them.
window.addEventListener('load', function () {
// Wait for registration to finish before dropping the <script> tag.
// Otherwise, the browser will load the script multiple times,
// potentially different versions.
var serviceWorkerUrl = 'flutter_service_worker.js?v=' + serviceWorkerVersion;
navigator.serviceWorker.register(serviceWorkerUrl)
.then((reg) => {
function waitForActivation(serviceWorker) {
serviceWorker.addEventListener('statechange', () => {
if (serviceWorker.state == 'activated') {
console.log('Installed new service worker.');
loadMainDartJs();
}
});
}
if (!reg.active && (reg.installing || reg.waiting)) {
// No active web worker and we have installed or are installing
// one for the first time. Simply wait for it to activate.
waitForActivation(reg.installing || reg.waiting);
} else if (!reg.active.scriptURL.endsWith(serviceWorkerVersion)) {
// When the app updates the serviceWorkerVersion changes, so we
// need to ask the service worker to update.
console.log('New service worker available.');
reg.update();
waitForActivation(reg.installing);
} else {
// Existing service worker is still good.
console.log('Loading app from service worker.');
loadMainDartJs();
}
});
// If service worker doesn't succeed in a reasonable amount of time,
// fallback to plaint <script> tag.
setTimeout(() => {
if (!scriptLoaded) {
console.warn(
'Failed to load app from service worker. Falling back to plain <script> tag.',
);
loadMainDartJs();
}
}, 4000);
});
} else {
// Service workers not supported. Just drop the <script> tag.
loadMainDartJs();
}
</script>
</body>
</html>
When I run the App in Chrome I get an Oh No! Error 5 in the browser and no error messages in the VS Code console.
If I include an await in the Firebase initialization line in index.html:
await firebase.initializeApp(firebaseConfig);
Again the Oh No! Error 5, but when I reload the page I get the following error on web_entrypoint.dart:
FirebaseError: Firebase: No Firebase App '[DEFAULT]' has been created - call Firebase App.initializeApp() (app/no-app). at Object.u [as app] (https://www.gstatic.com/firebasejs/8.6.1/firebase-app.js:1:18836) at Object.getApp (http://localhost:65003/packages/firebase_database_web/src/interop/app.dart.lib.js:630:89) //... more debug lines
In my lib/src/pages/main.dart, which works fine on IOS and Android, I'm making sure to initialize the Firebase services first ...
void main() async {
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp();
final prefs = PreferenciasUsuario();
await prefs.initPrefs();
await PushNotificationsProvider.initializeApp();
FirebaseDatabase database;
database = FirebaseDatabase.instance;
database.setPersistenceEnabled(true);
database.setPersistenceCacheSizeBytes(10000000);
runApp(MyApp());
}
I've read most of the answers on the subject on StackOverflow, but they haven't worked for me, I don't know if it's because I'm doing it particularly with Flutter.
How can I resolve the No Firebase App '[DEFAULT]' error and get my application run on the web?
