Build a User Management App with Flutter

This tutorial demonstrates how to build a basic user management app. The app authenticates and identifies the user, stores their profile information in the database, and allows the user to log in, update their profile details, and upload a profile photo. The app uses:

• Supabase Database - a Postgres database for storing your user data and Row Level Security so data is protected and users can only access their own information.
• Supabase Auth - users log in through magic links sent to their email (without having to set up passwords).
• Supabase Storage - users can upload a profile photo.

Project setup#

Before we start building we're going to set up our Database and API. This is as simple as starting a new Project in Supabase and then creating a "schema" inside the database.

Create a project#

1. Create a new project in the Supabase Dashboard.
2. Enter your project details.
3. Wait for the new database to launch.

Set up the database schema#

Now we are going to set up the database schema. We can use the "User Management Starter" quickstart in the SQL Editor, or you can just copy/paste the SQL from below and run it yourself.

Get the API Keys#

Now that you've created some database tables, you are ready to insert data using the auto-generated API. We just need to get the Project URL and anon key from the API settings.

1. Go to the API Settings page in the Dashboard.
2. Find your Project URL, anon, and service_role keys on this page.

Building the App#

Let's start building the Flutter app from scratch.

Initialize a Flutter app#

We can use flutter create to initialize an app called supabase_quickstart:

1flutter create supabase_quickstart

Then let's install the only additional dependency: supabase_flutter

Copy and paste the following line in your pubspec.yaml to install the package:

supabase_flutter: ^1.0.0

Run flutter pub get to install the dependencies.

Setup deep links#

Now that we have the dependencies installed let's setup deep links so users who have logged in via magic link or OAuth can come back to the app.

Add io.supabase.flutterquickstart://login-callback/ as a new redirect URL in the Dashboard.

That is it on Supabase's end and the rest are platform specific settings:

For Android, edit the android/app/src/main/AndroidManifest.xml file.

Add an intent-filter to enable deep linking:

<manifest ...>
  <!-- ... other tags -->
  <application ...>
    <activity ...>
      <!-- ... other tags -->

      <!-- Add this intent-filter for Deep Links -->
      <intent-filter>
        <action android:name="android.intent.action.VIEW" />
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="android.intent.category.BROWSABLE" />
        <!-- Accepts URIs that begin with YOUR_SCHEME://YOUR_HOST -->
        <data
          android:scheme="io.supabase.flutterquickstart"
          android:host="login-callback" />
      </intent-filter>

    </activity>
  </application>
</manifest>

For iOS, edit the ios/Runner/Info.plist file.

Add CFBundleURLTypes to enable deep linking:

<!-- ... other tags -->
<plist>
<dict>
  <!-- ... other tags -->

  <!-- Add this array for Deep Links -->
  <key>CFBundleURLTypes</key>
  <array>
    <dict>
      <key>CFBundleTypeRole</key>
      <string>Editor</string>
      <key>CFBundleURLSchemes</key>
      <array>
        <string>io.supabase.flutterquickstart</string>
      </array>
    </dict>
  </array>
  <!-- ... other tags -->
</dict>
</plist>

For web:

There are no additional configurations.

Main function#

Now that we have deep links ready let's initialize the Supabase client inside our main function with the API credentials that you copied earlier. These variables will be exposed on the app, and that's completely fine since we have Row Level Security enabled on our Database.

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await Supabase.initialize(
    url: 'YOUR_SUPABASE_URL',
    anonKey: 'YOUR_SUPABASE_ANON_KEY',
  );
  runApp(MyApp());
}

Setting up some constants and handy functions#

Let's also create a constant file to make it easier to use Supabase client. We will also include an extension method declaration to call showSnackBar with one line of code.

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

final supabase = Supabase.instance.client;

extension ShowSnackBar on BuildContext {
  void showSnackBar({
    required String message,
    Color backgroundColor = Colors.white,
  }) {
    ScaffoldMessenger.of(this).showSnackBar(SnackBar(
      content: Text(message),
      backgroundColor: backgroundColor,
    ));
  }

  void showErrorSnackBar({required String message}) {
    showSnackBar(message: message, backgroundColor: Colors.red);
  }
}

Set up Splash Screen#

Let's create a splash screen that will be shown to users right after they open the app. This screen retrieves the current session and redirects the user accordingly.

import 'package:flutter/material.dart';
import 'package:supabase_quickstart/constants.dart';

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

  @override
  _SplashPageState createState() => _SplashPageState();
}

class _SplashPageState extends State<SplashPage> {
  bool _redirectCalled = false;
  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    _redirect();
  }

  Future<void> _redirect() async {
    await Future.delayed(Duration.zero);
    if (_redirectCalled || !mounted) {
      return;
    }

    _redirectCalled = true;
    final session = supabase.auth.currentSession;
    if (session != null) {
      Navigator.of(context).pushReplacementNamed('/account');
    } else {
      Navigator.of(context).pushReplacementNamed('/login');
    }
  }

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      body: Center(child: CircularProgressIndicator()),
    );
  }
}

Set up a Login page#

Let's create a Flutter widget to manage logins and sign ups. We'll use Magic Links, so users can sign in with their email without using passwords. Notice that this page sets up a listener on the user's auth state using onAuthStateChange. A new event will fire when the user comes back to the app by clicking their magic link, which this page can catch and redirect the user accordingly.

import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:supabase_flutter/supabase_flutter.dart';

import 'package:supabase_quickstart/constants.dart';

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

  @override
  _LoginPageState createState() => _LoginPageState();
}

class _LoginPageState extends State<LoginPage> {
  bool _isLoading = false;
  bool _redirecting = false;
  late final TextEditingController _emailController;
  late final StreamSubscription<AuthState> _authStateSubscription;

  Future<void> _signIn() async {
    setState(() {
      _isLoading = true;
    });
    try {
      await supabase.auth.signInWithOtp(
        email: _emailController.text.trim(),
        emailRedirectTo:
            kIsWeb ? null : 'io.supabase.flutterquickstart://login-callback/',
      );
      if (mounted) {
        context.showSnackBar(message: 'Check your email for login link!');
        _emailController.clear();
      }
    } on AuthException catch (error) {
      context.showErrorSnackBar(message: error.message);
    } catch (error) {
      context.showErrorSnackBar(message: 'Unexpected error occurred');
    }

    setState(() {
      _isLoading = false;
    });
  }

  @override
  void initState() {
    _emailController = TextEditingController();
    _authStateSubscription = supabase.auth.onAuthStateChange.listen((data) {
      if (_redirecting) return;
      final session = data.session;
      if (session != null) {
        _redirecting = true;
        Navigator.of(context).pushReplacementNamed('/account');
      }
    });
    super.initState();
  }

  @override
  void dispose() {
    _emailController.dispose();
    _authStateSubscription.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Sign In')),
      body: ListView(
        padding: const EdgeInsets.symmetric(vertical: 18, horizontal: 12),
        children: [
          const Text('Sign in via the magic link with your email below'),
          const SizedBox(height: 18),
          TextFormField(
            controller: _emailController,
            decoration: const InputDecoration(labelText: 'Email'),
          ),
          const SizedBox(height: 18),
          ElevatedButton(
            onPressed: _isLoading ? null : _signIn,
            child: Text(_isLoading ? 'Loading' : 'Send Magic Link'),
          ),
        ],
      ),
    );
  }
}

Set up Account page#

After a user is signed in we can allow them to edit their profile details and manage their account. Let's create a new widget called account_page.dart for that.

import 'package:flutter/material.dart';
import 'package:supabase_flutter/supabase_flutter.dart';
import 'package:supabase_quickstart/components/avatar.dart';
import 'package:supabase_quickstart/constants.dart';

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

  @override
  _AccountPageState createState() => _AccountPageState();
}

class _AccountPageState extends State<AccountPage> {
  final _usernameController = TextEditingController();
  final _websiteController = TextEditingController();
  String? _avatarUrl;
  var _loading = false;

  /// Called once a user id is received within `onAuthenticated()`
  Future<void> _getProfile() async {
    setState(() {
      _loading = true;
    });

    try {
      final userId = supabase.auth.currentUser!.id;
      final data = await supabase
          .from('profiles')
          .select()
          .eq('id', userId)
          .single() as Map;
      _usernameController.text = (data['username'] ?? '') as String;
      _websiteController.text = (data['website'] ?? '') as String;
      _avatarUrl = (data['avatar_url'] ?? '') as String;
    } on PostgrestException catch (error) {
      context.showErrorSnackBar(message: error.message);
    } catch (error) {
      context.showErrorSnackBar(message: 'Unexpected exception occurred');
    }

    setState(() {
      _loading = false;
    });
  }

  /// Called when user taps `Update` button
  Future<void> _updateProfile() async {
    setState(() {
      _loading = true;
    });
    final userName = _usernameController.text.trim();
    final website = _websiteController.text.trim();
    final user = supabase.auth.currentUser;
    final updates = {
      'id': user!.id,
      'username': userName,
      'website': website,
      'updated_at': DateTime.now().toIso8601String(),
    };
    try {
      await supabase.from('profiles').upsert(updates);
      if (mounted) {
        context.showSnackBar(message: 'Successfully updated profile!');
      }
    } on PostgrestException catch (error) {
      context.showErrorSnackBar(message: error.message);
    } catch (error) {
      context.showErrorSnackBar(message: 'Unexpeted error occurred');
    }
    setState(() {
      _loading = false;
    });
  }

  Future<void> _signOut() async {
    try {
      await supabase.auth.signOut();
    } on AuthException catch (error) {
      context.showErrorSnackBar(message: error.message);
    } catch (error) {
      context.showErrorSnackBar(message: 'Unexpected error occurred');
    }
    if (mounted) {
      Navigator.of(context).pushReplacementNamed('/');
    }
  }

  @override
  void initState() {
    super.initState();
    _getProfile();
  }

  @override
  void dispose() {
    _usernameController.dispose();
    _websiteController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Profile')),
      body: ListView(
        padding: const EdgeInsets.symmetric(vertical: 18, horizontal: 12),
        children: [
          TextFormField(
            controller: _usernameController,
            decoration: const InputDecoration(labelText: 'User Name'),
          ),
          const SizedBox(height: 18),
          TextFormField(
            controller: _websiteController,
            decoration: const InputDecoration(labelText: 'Website'),
          ),
          const SizedBox(height: 18),
          ElevatedButton(
            onPressed: _updateProfile,
            child: Text(_loading ? 'Saving...' : 'Update'),
          ),
          const SizedBox(height: 18),
          TextButton(onPressed: _signOut, child: const Text('Sign Out')),
        ],
      ),
    );
  }
}

Launch!#

Now that we have all the components in place, let's update lib/main.dart:

import 'package:flutter/material.dart';
import 'package:supabase_flutter/supabase_flutter.dart';
import 'package:supabase_quickstart/pages/account_page.dart';
import 'package:supabase_quickstart/pages/login_page.dart';
import 'package:supabase_quickstart/pages/splash_page.dart';

Future<void> main() async {
  await Supabase.initialize(
    // TODO: Replace credentials with your own
    url: 'YOUR_SUPABASE_URL',
    anonKey: 'YOUR_SUPABASE_ANON_KEY',
  );
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Supabase Flutter',
      theme: ThemeData.dark().copyWith(
        primaryColor: Colors.green,
        textButtonTheme: TextButtonThemeData(
          style: TextButton.styleFrom(
            foregroundColor: Colors.green,
          ),
        ),
        elevatedButtonTheme: ElevatedButtonThemeData(
          style: ElevatedButton.styleFrom(
            foregroundColor: Colors.white,
            backgroundColor: Colors.green,
          ),
        ),
      ),
      initialRoute: '/',
      routes: <String, WidgetBuilder>{
        '/': (_) => const SplashPage(),
        '/login': (_) => const LoginPage(),
        '/account': (_) => const AccountPage(),
      },
    );
  }
}

Once that's done, run this in a terminal window to launch on Android or iOS:

1flutter run

Or for web, run the following command to launch it on localhost:3000

1flutter run -d web-server --web-hostname localhost --web-port 3000

And then open the browser to localhost:3000 and you should see the completed app.

Bonus: Profile photos#

Every Supabase project is configured with Storage for managing large files like photos and videos.

Making sure we have a public bucket#

We will be storing the image as a publicly sharable image. Make sure your avatars bucket is set to public, and if it is not, change the publicity by clicking the dot menu that appears when you hover over the bucket name. You should see an orange Public badge next to your bucket name if your bucket is set to public.

Adding image uploading feature to Account page#

We will use image_picker plugin to select an image from the device.

Add the following line in your pubspec.yaml file to install image_picker:

image_picker: ^0.8.4

Using image_picker requires some additional preparation depending on the platform. Follow the instruction on README.md of image_picker on how to set it up for the platform you are using.

Once you are done with all of the above, it is time to dive into coding.

Create an upload widget#

Let's create an avatar for the user so that they can upload a profile photo. We can start by creating a new component:

import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:supabase_flutter/supabase_flutter.dart';
import 'package:supabase_quickstart/constants.dart';

class Avatar extends StatefulWidget {
  const Avatar({
    super.key,
    required this.imageUrl,
    required this.onUpload,
  });

  final String? imageUrl;
  final void Function(String) onUpload;

  @override
  _AvatarState createState() => _AvatarState();
}

class _AvatarState extends State<Avatar> {
  bool _isLoading = false;

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        if (widget.imageUrl == null || widget.imageUrl!.isEmpty)
          Container(
            width: 150,
            height: 150,
            color: Colors.grey,
            child: const Center(
              child: Text('No Image'),
            ),
          )
        else
          Image.network(
            widget.imageUrl!,
            width: 150,
            height: 150,
            fit: BoxFit.cover,
          ),
        ElevatedButton(
          onPressed: _isLoading ? null : _upload,
          child: const Text('Upload'),
        ),
      ],
    );
  }

  Future<void> _upload() async {
    final picker = ImagePicker();
    final imageFile = await picker.pickImage(
      source: ImageSource.gallery,
      maxWidth: 300,
      maxHeight: 300,
    );
    if (imageFile == null) {
      return;
    }
    setState(() => _isLoading = true);

    try {
      final bytes = await imageFile.readAsBytes();
      final fileExt = imageFile.path.split('.').last;
      final fileName = '${DateTime.now().toIso8601String()}.$fileExt';
      final filePath = fileName;
      await supabase.storage.from('avatars').uploadBinary(
            filePath,
            bytes,
            fileOptions: FileOptions(contentType: imageFile.mimeType),
          );
      final imageUrlResponse = await supabase.storage
          .from('avatars')
          .createSignedUrl(filePath, 60 * 60 * 24 * 365 * 10);
      widget.onUpload(imageUrlResponse);
    } on StorageException catch (error) {
      if (mounted) {
        context.showErrorSnackBar(message: error.message);
      }
    } catch (error) {
      if (mounted) {
        context.showErrorSnackBar(message: 'Unexpected error occurred');
      }
    }

    setState(() => _isLoading = false);
  }
}

Add the new widget#

And then we can add the widget to the Account page as well as some logic to update the avatar_url whenever the user uploads a new avatar.

import 'package:flutter/material.dart';
import 'package:supabase_flutter/supabase_flutter.dart';
import 'package:supabase_quickstart/components/avatar.dart';
import 'package:supabase_quickstart/constants.dart';

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

  @override
  _AccountPageState createState() => _AccountPageState();
}

class _AccountPageState extends State<AccountPage> {
  final _usernameController = TextEditingController();
  final _websiteController = TextEditingController();
  String? _avatarUrl;
  var _loading = false;

  /// Called once a user id is received within `onAuthenticated()`
  Future<void> _getProfile() async {
    setState(() {
      _loading = true;
    });

    try {
      final userId = supabase.auth.currentUser!.id;
      final data = await supabase
          .from('profiles')
          .select()
          .eq('id', userId)
          .single() as Map;
      _usernameController.text = (data['username'] ?? '') as String;
      _websiteController.text = (data['website'] ?? '') as String;
      _avatarUrl = (data['avatar_url'] ?? '') as String;
    } on PostgrestException catch (error) {
      context.showErrorSnackBar(message: error.message);
    } catch (error) {
      context.showErrorSnackBar(message: 'Unexpected exception occurred');
    }

    setState(() {
      _loading = false;
    });
  }

  /// Called when user taps `Update` button
  Future<void> _updateProfile() async {
    setState(() {
      _loading = true;
    });
    final userName = _usernameController.text.trim();
    final website = _websiteController.text.trim();
    final user = supabase.auth.currentUser;
    final updates = {
      'id': user!.id,
      'username': userName,
      'website': website,
      'updated_at': DateTime.now().toIso8601String(),
    };
    try {
      await supabase.from('profiles').upsert(updates);
      if (mounted) {
        context.showSnackBar(message: 'Successfully updated profile!');
      }
    } on PostgrestException catch (error) {
      context.showErrorSnackBar(message: error.message);
    } catch (error) {
      context.showErrorSnackBar(message: 'Unexpeted error occurred');
    }
    setState(() {
      _loading = false;
    });
  }

  Future<void> _signOut() async {
    try {
      await supabase.auth.signOut();
    } on AuthException catch (error) {
      context.showErrorSnackBar(message: error.message);
    } catch (error) {
      context.showErrorSnackBar(message: 'Unexpected error occurred');
    }
    if (mounted) {
      Navigator.of(context).pushReplacementNamed('/');
    }
  }

  /// Called when image has been uploaded to Supabase storage from within Avatar widget
  Future<void> _onUpload(String imageUrl) async {
    try {
      final userId = supabase.auth.currentUser!.id;
      await supabase.from('profiles').upsert({
        'id': userId,
        'avatar_url': imageUrl,
      });
      if (mounted) {
        context.showSnackBar(message: 'Updated your profile image!');
      }
    } on PostgrestException catch (error) {
      context.showErrorSnackBar(message: error.message);
    } catch (error) {
      context.showErrorSnackBar(message: 'Unexpected error has occurred');
    }
    if (!mounted) {
      return;
    }

    setState(() {
      _avatarUrl = imageUrl;
    });
  }

  @override
  void initState() {
    super.initState();
    _getProfile();
  }

  @override
  void dispose() {
    _usernameController.dispose();
    _websiteController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Profile')),
      body: ListView(
        padding: const EdgeInsets.symmetric(vertical: 18, horizontal: 12),
        children: [
          Avatar(
            imageUrl: _avatarUrl,
            onUpload: _onUpload,
          ),
          const SizedBox(height: 18),
          TextFormField(
            controller: _usernameController,
            decoration: const InputDecoration(labelText: 'User Name'),
          ),
          const SizedBox(height: 18),
          TextFormField(
            controller: _websiteController,
            decoration: const InputDecoration(labelText: 'Website'),
          ),
          const SizedBox(height: 18),
          ElevatedButton(
            onPressed: _updateProfile,
            child: Text(_loading ? 'Saving...' : 'Update'),
          ),
          const SizedBox(height: 18),
          TextButton(onPressed: _signOut, child: const Text('Sign Out')),
        ],
      ),
    );
  }
}

Storage management#

If you upload additional profile photos, they'll accumulate in the avatars bucket because of their random names with only the latest being referenced from public.profiles and the older versions getting orphaned.

To automatically remove obsolete storage objects, extend the database triggers. Note that it is not sufficient to delete the objects from the storage.objects table because that would orphan and leak the actual storage objects in the S3 backend. Instead, invoke the storage API within Postgres via the http extension.

Enable the http extension for the extensions schema in the Dashboard. Then, define the following SQL functions in the SQL Editor to delete storage objects via the API:

create or replace function delete_storage_object(bucket text, object text, out status int, out content text)
returns record
language 'plpgsql'
security definer
as $$
declare
  project_url text := '<YOURPROJECTURL>';
  service_role_key text := '<YOURSERVICEROLEKEY>'; --  full access needed
  url text := project_url||'/storage/v1/object/'||bucket||'/'||object;
begin
  select
      into status, content
           result.status::int, result.content::text
      FROM extensions.http((
    'DELETE',
    url,
    ARRAY[extensions.http_header('authorization','Bearer '||service_role_key)],
    NULL,
    NULL)::extensions.http_request) as result;
end;
$$;

create or replace function delete_avatar(avatar_url text, out status int, out content text)
returns record
language 'plpgsql'
security definer
as $$
begin
  select
      into status, content
           result.status, result.content
      from public.delete_storage_object('avatars', avatar_url) as result;
end;
$$;

Next, add a trigger that removes any obsolete avatar whenever the profile is updated or deleted:

create or replace function delete_old_avatar()
returns trigger
language 'plpgsql'
security definer
as $$
declare
  status int;
  content text;
begin
  if coalesce(old.avatar_url, '') <> ''
      and (tg_op = 'DELETE' or (old.avatar_url <> new.avatar_url)) then
    select
      into status, content
      result.status, result.content
      from public.delete_avatar(old.avatar_url) as result;
    if status <> 200 then
      raise warning 'Could not delete avatar: % %', status, content;
    end if;
  end if;
  if tg_op = 'DELETE' then
    return old;
  end if;
  return new;
end;
$$;

create trigger before_profile_changes
  before update of avatar_url or delete on public.profiles
  for each row execute function public.delete_old_avatar();

Finally, delete the public.profile row before a user is deleted. If this step is omitted, you won't be able to delete users without first manually deleting their avatar image.

create or replace function delete_old_profile()
returns trigger
language 'plpgsql'
security definer
as $$
begin
  delete from public.profiles where id = old.id;
  return old;
end;
$$;

create trigger before_delete_user
  before delete on auth.users
  for each row execute function public.delete_old_profile();

Congratulations, you've built a fully functional user management app using Flutter and Supabase!

See also#

• Flutter Tutorial: building a Flutter chat app
• Flutter Tutorial - Part 2: Authentication and Authorization with RLS