Firebase 尽管调用了 Firebase.initializeApp() 但仍未初始化

Question

I'm writing my first Flutter up and trying to set up connection to Firebase. I have registered my app with Firebase as per instructions on the official website. I added the core and auth packages in the.yaml file, updated build.gradle files and imported them in my source code. Then I initialize Firebase by calling the proper method before starting the app. Whenever I try to sign in anonymously, I get the error:

[ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: [core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

I really don't know what's going on as I think I'm calling the method according to FlutterFire docs. Here's my main.dart file:

import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';
import 'package:roomie/views/sign_in_page.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Roomie',
      theme: ThemeData(
        primarySwatch: Colors.pink,
      ),
      home: SignInPage(),
    );
  }
}

And here's my sign in method. Whenever I press the sign in button, I get the error that Firebase has not been initialized:

import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';

class SignInPage extends StatelessWidget {

  Future<void> _signInAnonymously() async {
    final userCredentials = await FirebaseAuth.instance.signInAnonymously();
    print(userCredentials.user!.uid.toString());
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Roomie'),
        elevation: 2.0,
      ),
      body: _buildContent(),
      backgroundColor: Colors.grey[200],
    );
  }

  Widget _buildContent() {
    return Padding(
      padding: EdgeInsets.all(16.0),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Text(
            'Sign In',
            textAlign: TextAlign.center,
            style: TextStyle(
              fontSize: 26.0,
              fontWeight: FontWeight.w500,
            ),
          ),
          SizedBox(
            height: 50.0,
            child: ElevatedButton(
              onPressed: _signInAnonymously,
              child: Text(
                'Sign in anonymously',
                style: TextStyle(
                  color: Colors.black87,
                ),
              ),
              style: ElevatedButton.styleFrom(
                primary: Colors.white,
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(50),
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

Answer 1

1. I think it is either that you haven't placed the google_services.json file in the right path. Ensure that the file is placed in the app directory under the android directory.

2. Have you enabled Authentication in the Firebase console. Check your project console, click on Authentication, and ensure you enable your chosen authentication method in the "Sign-In methods".