Flutter POS

A Point of Sale (POS) application built with Flutter, demonstrating Clean Architecture principles and offline-first design patterns. This project serves as a learning resource and reference implementation for building Flutter apps with proper architecture and automatic data synchronization between local storage (SQLite) and cloud database (Firestore).

The app prioritizes local-first operations, storing all data in SQLite and automatically syncing with Firestore when online. When offline, all user actions (create, update, delete) are recorded as QueuedActions in the local database and automatically executed in sequence when internet connectivity is restored.

Demo APK

Download Demo APK

Features

Core Functionality

• Product Management: Full CRUD operations for products with image upload support
• Sales Transactions: POS interface with cart management and transaction history
• User Authentication: Firebase Authentication with Google Sign-In integration
• Account Management: User profile management and settings

Technical Implementation

• Offline-First Architecture: Works seamlessly without internet connection
• Automatic Data Sync: SQLite ↔ Firestore bidirectional synchronization
• Queued Actions: Automatic retry mechanism for offline operations (create, update, delete)
• Clean Architecture: Separation between presentation, domain, and data layers
• State Management: Provider pattern for state management
• Dependency Injection: Centralized DI setup for better code organization
• Unit Testing: Tests for datasources, repositories, and use cases
• Material Design 3: Material design 3 and Dark & Light theme switching support
• Customizable Theming: Adjustable colors and typography
• Multi-Platform: Supports Android, iOS, Windows, macOS, and Linux
• Error Handling: User-friendly error messages and states
• Reusable Widgets: Custom UI components for consistent design

Architecture

Project Structure

flutter_pos/
├── lib/
│   ├── app/                          # Application setup and configuration
│   │   ├── di/                       # Dependency injection
│   │   ├── error/                    # Error handling
│   │   └── routes/                   # App routing and navigation
│   │
│   ├── core/                         # Core utilities and shared resources
│   │   ├── assets/                   # Asset management
│   │   ├── common/                   # Common utilities (Result wrapper)
│   │   ├── constants/                # App constants
│   │   ├── database/                 # Local database configuration (sqflite)
│   │   ├── extensions/               # Dart extensions
│   │   ├── locale/                   # Localization
│   │   ├── services/                 # Core services
│   │   ├── themes/                   # App theming (colors, sizes, themes)
│   │   ├── usecase/                  # Base usecase interface
│   │   └── utilities/                # Helper utilities (formatters, loggers, etc.)
│   │
│   ├── data/                         # Data layer
│   │   ├── datasources/              # Data sources
│   │   │   ├── interfaces/           # Datasource interfaces
│   │   │   ├── local/                # Local datasources (sqflite)
│   │   │   └── remote/               # Remote datasources (Firestore, Firebase Auth)
│   │   ├── models/                   # Data models with JSON serialization
│   │   └── repositories/             # Repository implementations
│   │
│   ├── domain/                       # Domain layer (Business logic)
│   │   ├── entities/                 # Business entities
│   │   ├── repositories/             # Repository interfaces
│   │   └── usecases/                 # Use cases (business logic operations)
│   │
│   └── presentation/                 # Presentation layer (UI)
│       ├── providers/                # State management (Provider)
│       ├── screens/                  # UI screens
│       └── widgets/                  # Reusable UI components
│
├── test/                             # Unit and widget tests
└── assets/                           # Assets files

Getting Started

Prerequisites

• Flutter
• Dart
• Firebase account for backend services

Installation

1. Clone the repository:

   git clone https://github.com/elrizwiraswara/flutter_pos.git
   cd flutter_pos

2. Install dependencies:

   flutter pub get

3. Set up Firebase:

   • Create a new project on Firebase.
   • Follow the instructions to add Firebase to your Flutter app here.
   • Enable google authentication provider
   • Update cloud firestore rules to allow read write operation
   
   

   service cloud.firestore {
     match /databases/{database}/documents {
       match /{document=**} {
         allow read, write: if request.auth != null;
       }
     }
   }
   

   • Add cloud firestore indexes to enable query
   
   
   
   
   • Update firebase storage rules to allow read write operation
   
   

   service firebase.storage {
     match /b/{bucket}/o {
       match /{allPaths=**} {
         allow read, write: if request.auth != null;
       }
     }
   }
   

4. Set up your config.json file
   GOOGLE_SERVER_CLIENT_ID is Web client ID that you can get from your Firebase Google sign-in method provider

   {
     "GOOGLE_SERVER_CLIENT_ID": "xxxxxxxxxxxxx.apps.googleusercontent.com"
   }
   

5. Run the application:

   flutter run --dart-define-from-file config.json

Test

To test the application, run the following command:

flutter test --coverage

To view the test coverage you can use genhtml or test_cov_console

Contributing

Contributions are welcome! Please open an issue or submit a pull request for any bugs, feature requests, or improvements.

License

This project is licensed under the MIT License - see the LICENSE file for details.