We’re going to be building on top of the flutter todos example so we won’t go into the UI since it will all be the same. Instead, we’re going to focus on the repository layer as well as some of the blocs.
Our finished product will look very similar to the previous todos example, however, our todos will be synced across all devices and will update in real-time.
Before we get started, I want to give a special thanks to warriorCoder for helping make this tutorial possible!
Repositories
We’ll start off in the repository layer with the TodosRepository.
Todos Repository
Create a new package at the root level of our app called todos_repository.
Note: The reason for making the repository a standalone package is to illustrate that the repository should be decoupled from the application and can be reused across multiple apps.
Inside our todos_repository we need to create the following folder/file structure.
├── lib│ ├── src
│ │ ├── entities
│ │ │ ├── entities.dart
│ │ │ └── todo_entity.dart
│ │ ├── models
│ │ │ ├── models.dart
│ │ │ └── todo.dart
│ │ ├── todo.dart
│ │ ├── todo_entity.dart
│ │ ├── todos_repository.dart
│ │ └── firebase_todos_repository.dart
│ └── todos_repository.dart
└── pubspec.yaml
Dependencies
The pubspec.yaml should look like:
name: todos_repositoryversion: 1.0.0+1
environment:
sdk: “>=2.1.0 <3.0.0”dependencies:
flutter:
sdk: flutter
cloud_firestore: ^0.12.7
rxdart: ^0.22.0
equatable: ^0.3.0
firebase_core: ^0.4.0+7
Note: We can immediately see our todos_repository has a dependency on firebase_core and cloud_firestore.
Package Root
The todos_repository.dart directly inside lib is responsible for the public exports in our package and should look like:
library todos_repository;export ‘src/firebase_todos_repository.dart’;
export ‘src/models/models.dart’;
export ‘src/todos_repository.dart’;
Entities
Entities represent the data provided by our data provider.
The entities.dart file is a barrel file that exports the single todo_entity.dart file.
export ‘todo_entity.dart’;
Our TodoEntity is the representation of our Todo inside Firestore.
Let’s create todo_entity.dart and implement it.
import ‘package:cloud_firestore/cloud_firestore.dart’;
import ‘package:equatable/equatable.dart’;class TodoEntity extends Equatable {
final bool complete;
final String id;
final String note;
final String task;TodoEntity(this.task, this.id, this.note, this.complete);
Map<String, Object> toJson() {
return {
‘complete’: complete,
‘task’: task,
‘note’: note,
‘id’: id,
};
}@override
String toString() {
return ‘TodoEntity { complete: $complete, task: $task, note: $note, id: $id }’;
}static TodoEntity fromJson(Map<String, Object> json) {
return TodoEntity(
json[‘task’] as String,
json[‘id’] as String,
json[‘note’] as String,
json[‘complete’] as bool,
);
}static TodoEntity fromSnapshot(DocumentSnapshot snap) {
return TodoEntity(
snap.data[‘task’],
snap.documentID,
snap.data[‘note’],
snap.data[‘complete’],
);
}Map<String, Object> toDocument() {
return {
‘complete’: complete,
‘task’: task,
‘note’: note,
};
}
}
The toJson and fromJson are standard methods for converting to/from json. The fromSnapshot and toDocument are specific to Firestore.
Note: Firestore will automatically create the id for the document when we insert it. As such we don’t want to duplicate data by storing the id in an id field.
Models
Models will contain plain dart classes which we will work with in our Flutter Application. Having the separation between models and entities allows us to switch our data provider at any time and only have to change the thetoEntityandfromEntityconversion in our model layer.
Our models.dart is another barrel file which exports our single todo model.
export ‘todo.dart’;
Next, we need to create our todo.dart model.
import ‘package:meta/meta.dart’;
import ‘…/entities/entities.dart’;@immutable
class Todo {
final bool complete;
final String id;
final String note;
final String task;Todo(this.task, {this.complete = false, String note = ‘’, String id})
: this.note = note ?? ‘’,
this.id = id;Todo copyWith({bool complete, String id, String note, String task}) {
return Todo(
task ?? this.task,
complete: complete ?? this.complete,
id: id ?? this.id,
note: note ?? this.note,
);
}@override
int get hashCode =>
complete.hashCode ^ task.hashCode ^ note.hashCode ^ id.hashCode;@override
bool operator ==(Object other) =>
identical(this, other) ||
other is Todo &&
runtimeType == other.runtimeType &&
complete == other.complete &&
task == other.task &&
note == other.note &&
id == other.id;@override
String toString() {
return ‘Todo { complete: $complete, task: $task, note: $note, id: $id }’;
}TodoEntity toEntity() {
return TodoEntity(task, id, note, complete);
}static Todo fromEntity(TodoEntity entity) {
return Todo(
entity.task,
complete: entity.complete ?? false,
note: entity.note,
id: entity.id,
);
}
}
It’s important to note that having a model gives us the flexibility to change providers. Our application will always interact with our model (not our entity) so if we change data providers all we need to do is update our toEntity and fromEntity methods without needing to refactor our entire application.
Todos Repository
TodosRepositoryis our abstract base class which we can extend whenever we want to integrate with a differentTodosProvider.
Let’s create todos_repository.dart
import ‘dart:async’;import ‘package:todos_repository/todos_repository.dart’;
abstract class TodosRepository {
Future<void> addNewTodo(Todo todo);Future<void> deleteTodo(Todo todo);
Stream<List<Todo>> todos();
Future<void> updateTodo(Todo todo);
}
Note: Because we have this interface it is easy to add another type of datastore. If, for example, we wanted to use something like sembast all we would need to do is create a separate repository for handling the sembast specific code.
Firebase Todos Repository
FirebaseTodosRepositorymanages the integration with Firestore and implements ourTodosRepositoryinterface.
Let’s create firebase_todos_repository.dart and implement it!
import ‘dart:async’;import ‘package:cloud_firestore/cloud_firestore.dart’;
import ‘package:todos_repository/todos_repository.dart’;
import ‘entities/entities.dart’;class FirebaseTodosRepository implements TodosRepository {
final todoCollection = Firestore.instance.collection(‘todos’);@override
Future<void> addNewTodo(Todo todo) {
return todoCollection.add(todo.toEntity().toDocument());
}@override
Future<void> deleteTodo(Todo todo) async {
return todoCollection.document(todo.id).delete();
}@override
Stream<List<Todo>> todos() {
return todoCollection.snapshots().map((snapshot) {
return snapshot.documents
.map((doc) => Todo.fromEntity(TodoEntity.fromSnapshot(doc)))
.toList();
});
}@override
Future<void> updateTodo(Todo update) {
return todoCollection
.document(update.id)
.updateData(update.toEntity().toDocument());
}
}
That’s it for our TodosRepository, next we need to create a simple UserRepository to manage authenticating our users.
User Repository
Create a new package at the root level of our app called useer_repository.
Inside our user_repository create the following folder/file structure.
├── lib│ ├── src
│ │ └── user_repository.dart
│ └── user_repository.dart
└── pubspec.yaml
Dependencies
The pubspec.yaml should look like:
name: user_repositoryversion: 1.0.0+1
environment:
sdk: “>=2.1.0 <3.0.0”dependencies:
flutter:
sdk: flutter
firebase_auth: ^0.11.1+12
Note: We can immediately see our user_repository has a dependency on firebase_auth.
Package Root
The user_repository.dart directly inside lib should look like:
library user_repository;export ‘src/user_repository.dart’;
User Repository
UserRepository is our abstract base class which we can extend whenever we want to integrate with a different provider`.Let’s create user_repository.dart and implement it!
abstract class UserRepository {
Future<bool> isAuthenticated();
Future<void> authenticate();
Future<String> getUserId();
}
Firebase User Repository
FirebaseUserRepositorymanages the integration with Firebase and implements ourUserRepositoryinterface.
Let’s open firebaseuserrepository.dart and implement it!
import ‘package:firebase_auth/firebase_auth.dart’;
import ‘package:user_repository/user_repository.dart’;class FirebaseUserRepository implements UserRepository {
final FirebaseAuth _firebaseAuth;FirebaseUserRepository({FirebaseAuth firebaseAuth})
: _firebaseAuth = firebaseAuth ?? FirebaseAuth.instance;Future<bool> isAuthenticated() async {
final currentUser = await _firebaseAuth.currentUser();
return currentUser != null;
}Future<void> authenticate() {
return _firebaseAuth.signInAnonymously();
}Future<String> getUserId() async {
return (await _firebaseAuth.currentUser()).uid;
}
}
That’s it for our UserRepository, next we need to setup our Flutter app to use our new repositories.
Flutter App
Setup
Let’s create a new Flutter app called flutter_firestore_todos. We can replace the contents of the pubspec.yaml with the following:
name: flutter_firestore_todos
description: A new Flutter project.version: 1.0.0+1
environment:
sdk: “>=2.1.0 <3.0.0”dependencies:
flutter:
sdk: flutter
flutter_bloc: ^0.20.0
todos_repository:
path: todos_repository
user_repository:
path: user_repository
equatable: ^0.3.0flutter:
uses-material-design: true
Note: We’re adding our todos_repository and user_repository as external dependencies.
Authentication Bloc
Since we want to be able to sign in our users, we’ll need to create an AuthenticationBloc.
Note: If you haven’t already checked out the flutter firebase login tutorial, I highly recommend checking it out now because we’re simply going to reuse the same AuthenticationBloc.
Authentication Events
import ‘package:equatable/equatable.dart’;
import ‘package:meta/meta.dart’;@immutable
abstract class AuthenticationEvent extends Equatable {
AuthenticationEvent([List props = const []]) : super(props);
}class AppStarted extends AuthenticationEvent {
@override
String toString() => ‘AppStarted’;
}
Authentication States
import ‘package:equatable/equatable.dart’;
import ‘package:meta/meta.dart’;@immutable
abstract class AuthenticationState extends Equatable {
AuthenticationState([List props = const []]) : super(props);
}class Uninitialized extends AuthenticationState {
@override
String toString() => ‘Uninitialized’;
}class Authenticated extends AuthenticationState {
final String userId;Authenticated(this.userId) : super([userId]);
@override
String toString() => ‘Authenticated { userId: $userId }’;
}class Unauthenticated extends AuthenticationState {
@override
String toString() => ‘Unauthenticated’;
}
Authentication Bloc
import ‘dart:async’;
import ‘package:bloc/bloc.dart’;
import ‘package:meta/meta.dart’;
import ‘package:user_repository/user_repository.dart’;
import ‘package:flutter_firestore_todos/blocs/authentication_bloc/bloc.dart’;class AuthenticationBloc
extends Bloc<AuthenticationEvent, AuthenticationState> {
final UserRepository _userRepository;AuthenticationBloc({@required UserRepository userRepository})
: assert(userRepository != null),
_userRepository = userRepository;@override
AuthenticationState get initialState => Uninitialized();@override
Stream<AuthenticationState> mapEventToState(
AuthenticationEvent event,
) async* {
if (event is AppStarted) {
yield* _mapAppStartedToState();
}
}Stream<AuthenticationState> _mapAppStartedToState() async* {
try {
final isSignedIn = await _userRepository.isAuthenticated();
if (!isSignedIn) {
await _userRepository.authenticate();
}
final userId = await userRepository.getUserId();
yield Authenticated(userId);
} catch () {
yield Unauthenticated();
}
}
}
Now that our AuthenticationBloc is finished, we need to modify the TodosBloc from the original todos tutorial to consume the new TodosRepository.
Todos Bloc
import ‘dart:async’;
import ‘package:bloc/bloc.dart’;
import ‘package:meta/meta.dart’;
import ‘package:flutter_firestore_todos/blocs/todos/todos.dart’;
import ‘package:todos_repository/todos_repository.dart’;class TodosBloc extends Bloc<TodosEvent, TodosState> {
final TodosRepository _todosRepository;
StreamSubscription _todosSubscription;TodosBloc({@required TodosRepository todosRepository})
: assert(todosRepository != null),
_todosRepository = todosRepository;@override
TodosState get initialState => TodosLoading();@override
Stream<TodosState> mapEventToState(TodosEvent event) async* {
if (event is LoadTodos) {
yield* _mapLoadTodosToState();
} else if (event is AddTodo) {
yield* _mapAddTodoToState(event);
} else if (event is UpdateTodo) {
yield* _mapUpdateTodoToState(event);
} else if (event is DeleteTodo) {
yield* _mapDeleteTodoToState(event);
} else if (event is ToggleAll) {
yield* _mapToggleAllToState();
} else if (event is ClearCompleted) {
yield* _mapClearCompletedToState();
} else if (event is TodosUpdated) {
yield* _mapTodosUpdateToState(event);
}
}Stream<TodosState> _mapLoadTodosToState() async* {
_todosSubscription?.cancel();
_todosSubscription = _todosRepository.todos().listen(
(todos) {
dispatch(
TodosUpdated(todos),
);
},
);
}Stream<TodosState> _mapAddTodoToState(AddTodo event) async* {
_todosRepository.addNewTodo(event.todo);
}Stream<TodosState> _mapUpdateTodoToState(UpdateTodo event) async* {
_todosRepository.updateTodo(event.updatedTodo);
}Stream<TodosState> _mapDeleteTodoToState(DeleteTodo event) async* {
_todosRepository.deleteTodo(event.todo);
}Stream<TodosState> _mapToggleAllToState() async* {
final state = currentState;
if (state is TodosLoaded) {
final allComplete = state.todos.every((todo) => todo.complete);
final List<Todo> updatedTodos = state.todos
.map((todo) => todo.copyWith(complete: !allComplete))
.toList();
updatedTodos.forEach((updatedTodo) {
_todosRepository.updateTodo(updatedTodo);
});
}
}Stream<TodosState> _mapClearCompletedToState() async* {
final state = currentState;
if (state is TodosLoaded) {
final List<Todo> completedTodos =
state.todos.where((todo) => todo.complete).toList();
completedTodos.forEach((completedTodo) {
_todosRepository.deleteTodo(completedTodo);
});
}
}Stream<TodosState> _mapTodosUpdateToState(TodosUpdated event) async* {
yield TodosLoaded(event.todos);
}@override
void dispose() {
_todosSubscription?.cancel();
super.dispose();
}
}
The main difference between our new TodosBloc and the original one is in the new one, everything is Stream based rather than Future based.
Stream<TodosState> _mapLoadTodosToState() async* {
_todosSubscription?.cancel();
_todosSubscription = _todosRepository.todos().listen(
(todos) {
dispatch(
TodosUpdated(todos),
);
},
);
}
When we load our todos, we are subscribing to the TodosRepository and every time a new todo comes in, we dispatch a TodosUpdated event. We then handle all TodosUpdates via:
Stream<TodosState> _mapTodosUpdateToState(TodosUpdated event) async* {
yield TodosLoaded(event.todos);
}
Putting it all together
The last thing we need to modify is our main.dart.
import ‘package:flutter/material.dart’;
import ‘package:bloc/bloc.dart’;
import ‘package:flutter_bloc/flutter_bloc.dart’;
import ‘package:flutter_firestore_todos/blocs/authentication_bloc/bloc.dart’;
import ‘package:todos_repository/todos_repository.dart’;
import ‘package:flutter_firestore_todos/blocs/blocs.dart’;
import ‘package:flutter_firestore_todos/screens/screens.dart’;
import ‘package:user_repository/user_repository.dart’;void main() {
BlocSupervisor.delegate = SimpleBlocDelegate();
runApp(TodosApp());
}class TodosApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MultiBlocProvider(
providers: [
BlocProvider<AuthenticationBloc>(
builder: (context) {
return AuthenticationBloc(
userRepository: FirebaseUserRepository(),
)…dispatch(AppStarted());
},
),
BlocProvider<TodosBloc>(
builder: (context) {
return TodosBloc(
todosRepository: FirebaseTodosRepository(),
)…dispatch(LoadTodos());
},
)
],
child: MaterialApp(
title: ‘Firestore Todos’,
routes: {
‘/’: (context) {
return BlocBuilder<AuthenticationBloc, AuthenticationState>(
builder: (context, state) {
if (state is Authenticated) {
final todosBloc = BlocProvider.of<TodosBloc>(context);
return MultiBlocProvider(
providers: [
BlocProvider<TabBloc>(
builder: (context) => TabBloc(),
),
BlocProvider<FilteredTodosBloc>(
builder: (context) =>
FilteredTodosBloc(todosBloc: todosBloc),
),
BlocProvider<StatsBloc>(
builder: (context) => StatsBloc(todosBloc: todosBloc),
),
],
child: HomeScreen(),
);
}
if (state is Unauthenticated) {
return Center(
child: Text(‘Could not authenticate with Firestore’),
);
}
return Center(child: CircularProgressIndicator());
},
);
},
‘/addTodo’: (context) {
final todosBloc = BlocProvider.of<TodosBloc>(context);
return AddEditScreen(
onSave: (task, note) {
todosBloc.dispatch(
AddTodo(Todo(task, note: note)),
);
},
isEditing: false,
);
},
},
),
);
}
}
The main difference is we’ve wrapped our entire application in a MultiBlocProvider which initializes and provides the AuthenticationBloc and TodosBloc. We then, only render the todos app if the AuthenticationState is Authenticated using BlocBuilder. Everything else remains the same as in the previous todos tutorial.
That’s all there is to it! We’ve now successfully implemented a firestore todos app in flutter using the bloc and flutter_bloc packages and we’ve successfully separated our presentation layer from our business logic while also building an app that updates in real-time.
The full source for this example can be found here.
Thanks for reading ❤
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Further reading
☞ Learn Flutter & Dart to Build iOS & Android Apps
☞ Flutter & Dart - The Complete Flutter App Development Course
☞ Dart and Flutter: The Complete Developer’s Guide
☞ Flutter Tutorial - Flight List UI Example In Flutter
☞ Flutter Tutorial for Beginners - Full Tutorial
☞ A Beginners Guide to the Flutter Bottom Sheet
☞ Flutter Course - Full Tutorial for Beginners (Build iOS and Android Apps)
☞ Flutter Tutorial For Beginners - Build Your First Flutter App
☞ Building the SwiftUI Sample App in Flutter
☞ Building Cryptocurrency Pricing App with Flutter
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