Riverpod State Management: Project Setup for Notes App

4.3.1 Project Setup: Notes App

In this section, we will embark on a journey to build a simple yet functional Notes app using Riverpod for state management. This project will serve as a practical example of how to leverage Riverpod’s capabilities to manage state in a Flutter application. We will cover the entire process from setting up the project to planning the architecture and implementing core features such as creating, editing, and deleting notes.

App Overview

Before diving into the technical setup, let’s outline the key features of our Notes app:

• Create Notes: Users can add new notes with a title and content.
• Edit Notes: Existing notes can be modified to update their content.
• Delete Notes: Users can remove notes they no longer need.
• List View: Display all notes in a list format for easy navigation.
• Detail View: View the full content of a note in a dedicated screen.

These features will allow us to explore various aspects of state management, including handling lists of items, managing individual item states, and updating the UI in response to state changes.

Setting Up the Project

Step 1: Create a New Flutter Project

To begin, we need to create a new Flutter project. Open your terminal and run the following command:

flutter create notes_app

This command will generate a new Flutter project with the default structure. Navigate into the project directory:

cd notes_app

Step 2: Add Riverpod to Your Project

Riverpod is a powerful state management solution for Flutter. To add it to your project, open the pubspec.yaml file and add the following dependencies:

dependencies:
  flutter:
    sdk: flutter
  flutter_riverpod: ^2.0.0

After adding the dependencies, run the following command to install them:

flutter pub get

This will fetch the Riverpod package and make it available in your project.

Step 3: Set Up the Project Structure

Organizing your project structure is crucial for maintainability and scalability. Here’s a suggested structure for our Notes app:

lib/
  |- main.dart
  |- models/
      |- note.dart
  |- providers/
      |- note_provider.dart
  |- screens/
      |- home_screen.dart
      |- note_detail_screen.dart
      |- note_edit_screen.dart
  |- widgets/
      |- note_list.dart
      |- note_item.dart

• models/: Contains data models, such as note.dart, which defines the structure of a note.
• providers/: Houses provider logic, including note_provider.dart, where we manage the state of notes.
• screens/: Contains the UI screens of the app, such as home_screen.dart for the main list of notes and note_detail_screen.dart for viewing a note.
• widgets/: Includes reusable UI components like note_list.dart and note_item.dart.

Planning the App Architecture

Before writing any code, it’s essential to plan the app’s architecture. This involves deciding how data flows through the app, how state is managed, and how different components interact.

State Management with Riverpod

Riverpod offers a robust way to manage state in Flutter applications. It provides a variety of providers to handle different types of state, including:

• Provider: For immutable state.
• StateProvider: For simple mutable state.
• StateNotifierProvider: For complex state logic with a StateNotifier.
• FutureProvider: For asynchronous data.
• StreamProvider: For stream-based data.

For our Notes app, we’ll primarily use StateNotifierProvider to manage the list of notes, as it allows us to encapsulate complex state logic and easily notify listeners of state changes.

Data Flow and UI Interaction

The app will follow a unidirectional data flow pattern, where data flows in a single direction:

1. State: Managed by Riverpod providers.
2. UI: Reacts to state changes and displays data.
3. User Actions: Trigger state updates through providers.

This pattern ensures a clear separation of concerns and makes the app easier to reason about and maintain.

Designing the Note Model

Let’s define the data model for a note. Create a new file note.dart in the models directory:

class Note {
  final String id;
  final String title;
  final String content;

  Note({
    required this.id,
    required this.title,
    required this.content,
  });
}

This simple model includes an id, title, and content for each note.

Implementing the Note Provider

Next, we’ll implement the provider logic to manage the state of notes. Create a file note_provider.dart in the providers directory:

import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../models/note.dart';

class NoteNotifier extends StateNotifier<List<Note>> {
  NoteNotifier() : super([]);

  void addNote(Note note) {
    state = [...state, note];
  }

  void editNote(String id, String title, String content) {
    state = [
      for (final note in state)
        if (note.id == id)
          Note(
            id: note.id,
            title: title,
            content: content,
          )
        else
          note,
    ];
  }

  void deleteNote(String id) {
    state = state.where((note) => note.id != id).toList();
  }
}

final noteProvider = StateNotifierProvider<NoteNotifier, List<Note>>((ref) {
  return NoteNotifier();
});

In this provider, we define methods to add, edit, and delete notes. The StateNotifier manages a list of Note objects, and the StateNotifierProvider exposes this state to the rest of the app.

Conclusion

Setting up a Flutter project with Riverpod for state management involves careful planning and organization. By defining a clear architecture and utilizing Riverpod’s powerful features, we can build a robust Notes app that efficiently manages state. In the following sections, we’ll dive deeper into implementing the UI and integrating these components to create a fully functional application.

Quiz Time!