Error: No Firebase App '[DEFAULT]' has been created - call Firebase App.initializeApp()

Solution 1:

You are probably invoking firebase before the app is initialized. All calls to firebase must come after .initializeApp();

firebase.initializeApp(config);
var db = firebase.firestore();

Solution 2:

Complete tutorial source link

Use initializeApp before @NgModule

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { RouteReuseStrategy } from '@angular/router';

import { IonicModule, IonicRouteStrategy } from '@ionic/angular';
import { SplashScreen } from '@ionic-native/splash-screen/ngx';
import { StatusBar } from '@ionic-native/status-bar/ngx';

import { AppComponent } from './app.component';
import { AppRoutingModule } from './app-routing.module';
import { environment } from 'src/environments/environment';
import { AuthenticateService } from './services/authentication.service';
import { AngularFireAuthModule } from '@angular/fire/auth';

import * as firebase from 'firebase';

firebase.initializeApp(environment.firebase);

@NgModule({
  declarations: [AppComponent],
  entryComponents: [],
  imports: [
    BrowserModule, 
    IonicModule.forRoot(), 
    AppRoutingModule,
    AngularFireAuthModule
  ],
  providers: [
    StatusBar,
    SplashScreen,
    AuthenticateService,
    { provide: RouteReuseStrategy, useClass: IonicRouteStrategy }
  ],
  bootstrap: [AppComponent]
})
export class AppModule {}

Solution 3:

If you using Dart and Flutter

1. add firebase_core dependency to pubspac.ymal.
2. go to main.dart
3. import 'package:firebase_core/firebase_core.dart';

4.add async in main()

follow my code

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  var fsconnect = FirebaseFirestore.instance;

  myget() async {
    var d = await fsconnect.collection("students").get();
    // print(d.docs[0].data());

    for (var i in d.docs) {
      print(i.data());
    }
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
      appBar: AppBar(
        title: Text('Firebase Firestore App'),
      ),
      body: Column(
        children: <Widget>[
          RaisedButton(
            child: Text('send data'),
            onPressed: () {
              fsconnect.collection("students").add({
                'name': 'sarah',
                'title': 'xyz',
                'email': '[email protected]',
              });
              print("send ..");
            },
          ),
          RaisedButton(
            child: Text('get data'),
            onPressed: () {
              myget();
              print("get data ...");
            },
          )
        ],
      ),
    ));
  }
}

Solution 4:

My problem was because I added a second parameter:

AngularFireModule.initializeApp(firebaseConfig, 'reservas')

if I remove the second parameter it works fine:

AngularFireModule.initializeApp(firebaseConfig)