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Finds a error when try to run my flutter project

I’m working on a Flutter app for Android and have encountered an issue when i add if a user is present then there is a no need for login again after refreshing the page . in the flutter project by creating the file CheckUser but when i call this file from the main dart then it gives me the error with a red screen with text —- Expected a value of type ‘Widget ‘, but got one of type ‘_Future<dynamic>’ See also:https://flutter.dev/docs/testing/error.

the problems comes after implementing the checkuser file in my projects which checks that user already have account or not .

here are the files what i used in my project

CheckUser file

import 'package:firebase/login.dart';
import 'package:firebase/main.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';

class CheckUser extends StatefulWidget {
  const CheckUser({super.key});

  @override
  State<CheckUser> createState() => _CheckUserState();
}

class _CheckUserState extends State<CheckUser> {
  @override
  Widget build(BuildContext context) {
    return checkuser();
  }
  checkuser()async{
    final user = FirebaseAuth.instance.currentUser;
    if(user!=null ){
      return HomeScreen();
    }
    else {
      return Loginpage();
    }
  }


}

main dart file

import 'package:firebase/checkuser.dart';
import 'package:firebase/login.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';

void main()async{
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp(
      options: FirebaseOptions(apiKey: "AIzaSyDQZxWx776Vhl7Hw4VG5RhaSPX13v6ygRk",
          appId: "1:1049018787351:android:309401ce75103c0f171e52",
          messagingSenderId: "1049018787351",
          projectId: "harsh-c8ebd")
  );
  runApp(const MyApp());
}


class MyApp extends StatelessWidget {
  const MyApp({super.key});
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: CheckUser(),
    );
  }
}

class HomeScreen extends StatefulWidget {
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home Screen'),
      ),
      body: Text('hello'),
    );
  }
}

Login in file

import 'package:firebase/helper.dart';
import 'package:firebase/main.dart';
import 'package:firebase/signuppage.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

class Loginpage extends StatefulWidget {
  const Loginpage({Key? key}) : super(key: key);

  @override
  State<Loginpage> createState() => _LoginpageState();
}

class _LoginpageState extends State<Loginpage> {
  TextEditingController emailcontroller = TextEditingController();
  TextEditingController passwordcontroller = TextEditingController();

  login(String email, String password) async {
    if (email == "" && password == "") {
      return Helper.CustomAlertBox(context, "Enter required fields");
    } else {
      try {
        UserCredential userCredential = await FirebaseAuth.instance
            .signInWithEmailAndPassword(email: email, password: password);
        Navigator.push(
          context,
          MaterialPageRoute(builder: (context) => SignUpPage()),
        );
      } on FirebaseAuthException catch (ex) {
        return Helper.CustomAlertBox(context, ex.code.toString());
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Login page"),
        centerTitle: true,
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Helper.CustomTextField(emailcontroller, "Email", Icons.mail, false),
          Helper.CustomTextField(
              passwordcontroller, "Password", Icons.password, true),
          SizedBox(height: 30),
          Helper.CustomButton(
                () {
              login(emailcontroller.text.toString(),
                  passwordcontroller.text.toString());
            },
            "Login",
          ),
          SizedBox(height: 20),
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              Text("Don't have an account?"),
              TextButton(
                onPressed: () {
                  Navigator.push(context,
                      MaterialPageRoute(builder: (context) => SignUpPage()));
                },
                child: Text(
                  "Sign up",
                  style: TextStyle(fontSize: 20),
                ),
              )
            ],
          )
        ],
      ),
    );
  }
}

Sign up file

import 'package:firebase/helper.dart';
import 'package:firebase/main.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

class SignUpPage extends StatefulWidget {
  const SignUpPage({Key? key}) : super(key: key);

  @override
  State<SignUpPage> createState() => _SignUpPageState();
}

class _SignUpPageState extends State<SignUpPage> {
  TextEditingController emailcontroller = TextEditingController();
  TextEditingController passwordcontroller = TextEditingController();

  signUp(String email, String password) async {
    if (email == "" && password == "") {
      Helper.CustomAlertBox(context, "Enter required fields");
    } else {
      try {
        UserCredential userCredential = await FirebaseAuth.instance
            .createUserWithEmailAndPassword(email: email, password: password);
        Navigator.push(
          context,
          MaterialPageRoute(builder: (context) => HomeScreen()),
        );
      } on FirebaseAuthException catch (ex) {
        return Helper.CustomAlertBox(context, ex.code.toString());
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Sign Up page"),
        centerTitle: true,
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Helper.CustomTextField(emailcontroller, "Email", Icons.mail, false),
          Helper.CustomTextField(passwordcontroller, "Password", Icons.password, true),
          SizedBox(height: 20),
          Helper.CustomButton(
                () {
              signUp(emailcontroller.text.toString(), passwordcontroller.text.toString());
            },
            "Sign Up",
          ),
        ],
      ),
    );
  }
}

Helper file

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

class Helper {
  static  CustomTextField(TextEditingController controller, String text, IconData iconData, bool tohide) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 25, vertical: 40),
      child: TextField(
        controller: controller,
        obscureText: tohide,
        decoration: InputDecoration(
          hintText: text,
          suffixIcon: Icon(iconData),
          border: OutlineInputBorder(
            borderRadius: BorderRadius.circular(25),
          ),
        ),
      ),
    );
  }

  static  CustomButton(VoidCallback voidCallback, String text) {
    return SizedBox(
      height: 50,
      width: 300,
      child: ElevatedButton(
        onPressed: voidCallback,
        style: ElevatedButton.styleFrom(
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(25),
          ),
        ),
        child: Text(
          text,
          style: TextStyle(
            color: Colors.red,
            fontSize: 20,
          ),
        ),
      ),
    );
  }

  static  CustomAlertBox(BuildContext context, String text) {
    return showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: Text(text),
          actions: [
            TextButton(
              onPressed: () {
                Navigator.pop(context);
              },
              child: Text("OK"),
            ),
          ],

        );
      },
    );
  }
}

pubsyml file

name: firebase
description: "A new Flutter project."
# The following line prevents the package from being accidentally published to
# pub.dev using `flutter pub publish`. This is preferred for private packages.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev

# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number is used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
# In Windows, build-name is used as the major, minor, and patch parts
# of the product and file versions while build-number is used as the build suffix.
version: 1.0.0+1

environment:
  sdk: '>=3.2.4 <4.0.0'

# Dependencies specify other packages that your package needs in order to work.
# To automatically upgrade your package dependencies to the latest versions
# consider running `flutter pub upgrade --major-versions`. Alternatively,
# dependencies can be manually updated by changing the version numbers below to
# the latest version available on pub.dev. To see which dependencies have newer
# versions available, run `flutter pub outdated`.
dependencies:
  flutter:
    sdk: flutter


  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^1.0.2
  firebase_core: ^2.27.0
  firebase_auth: ^4.17.8

dev_dependencies:
  flutter_test:
    sdk: flutter

  # The "flutter_lints" package below contains a set of recommended lints to
  # encourage good coding practices. The lint set provided by the package is
  # activated in the `analysis_options.yaml` file located at the root of your
  # package. See that file for information about deactivating specific lint
  # rules and activating additional ones.
  flutter_lints: ^3.0.2

# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec

# The following section is specific to Flutter packages.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  # To add assets to your application, add an assets section, like this:
  # assets:
  #   - images/a_dot_burr.jpeg
  #   - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages
enter image description here
Tags:

2

Answers


  1. 0

    Add Widget to return type of checkuser function and remove async keyword.

    Widget checkuser(){
    final user = FirebaseAuth.instance.currentUser;
    if(user!=null ){
      return HomeScreen();
    }
    else {
      return Loginpage();
    }
  }
    Login or Signup to reply.
  2. 0

    Since your checkuser function is async, you need to wrap it in a FutureBuilder to render its content. The simplest way to do that:

    class _CheckUserState extends State<CheckUser> {
  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      future: checkuser(),
      builder: (_, snapshot) {
        if (snapshot.hasError) return Text("ERROR: ${snapshot.error}");
        if (!snapshot.hasData) return const CircularProgressIndicator();
        return snapshot.data!;
      }
    )
  }
  checkuser() async {
    final user = FirebaseAuth.instance.currentUser;
    if(user!=null) {
      return HomeScreen();
    }
    else {
      return Loginpage();
    }
  }
}
    Login or Signup to reply.
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