Project: Inventory Management System in Dart

Project Goal

Build an inventory management system for a small store: add products, track stock levels, process sales, get low-stock alerts, and generate inventory reports. Covers OOP, generics, sorting, and business logic.

Full Code

class Product {
  final String id;
  final String name;
  final String category;
  final double price;
  int quantity;
  final int lowStockThreshold;

  Product({required this.id, required this.name, required this.category,
           required this.price, required this.quantity, this.lowStockThreshold = 10});

  bool get isLowStock => quantity <= lowStockThreshold;
  double get totalValue => price * quantity;

  @override String toString() =>
      '$${id.padRight(8)} $${name.padRight(25)} \$$${price.toStringAsFixed(2).padLeft(8)} '
      'Qty:$${quantity.toString().padLeft(5)} $${isLowStock ? "⚠ LOW" : ""}';
}

class SaleRecord {
  final String productId;
  final String productName;
  final int quantity;
  final double unitPrice;
  final DateTime soldAt;

  SaleRecord({required this.productId, required this.productName,
              required this.quantity, required this.unitPrice})
      : soldAt = DateTime.now();

  double get total => quantity * unitPrice;
}

class Inventory {
  final Map<String, Product> _products = {};
  final List<SaleRecord> _sales = [];

  void addProduct(Product product) {
    _products[product.id] = product;
    print('Added: $${product.name}');
  }

  void restock(String id, int qty) {
    var p = _findProduct(id);
    p.quantity += qty;
    print('Restocked $${p.name}: +$qty (now $${p.quantity})');
  }

  SaleRecord sell(String id, int qty) {
    var p = _findProduct(id);
    if (qty > p.quantity) throw StateError('Not enough stock. Have $${p.quantity}, need $qty');
    p.quantity -= qty;
    var sale = SaleRecord(productId: id, productName: p.name, quantity: qty, unitPrice: p.price);
    _sales.add(sale);
    if (p.isLowStock) print('⚠ Low stock alert: $${p.name} ($${p.quantity} remaining)');
    return sale;
  }

  Product _findProduct(String id) {
    var p = _products[id];
    if (p == null) throw ArgumentError('Product not found: $id');
    return p;
  }

  List<Product> get lowStockProducts =>
      _products.values.where((p) => p.isLowStock).toList();

  void report() {
    print('\n===== INVENTORY REPORT =====');
    print('$${'ID'.padRight(8)} $${'Name'.padRight(25)} $${'Price'.padLeft(9)} $${'Qty'.padLeft(8)}');
    print('-' * 60);
    var sorted = _products.values.toList()
      ..sort((a, b) => a.category.compareTo(b.category));
    String? lastCat;
    for (var p in sorted) {
      if (p.category != lastCat) {
        print('\n[$${p.category}]');
        lastCat = p.category;
      }
      print(p);
    }
    var totalVal = _products.values.fold(0.0, (s, p) => s + p.totalValue);
    print('\nTotal inventory value: \$$${totalVal.toStringAsFixed(2)}');
    print('Total products: $${_products.length}');
    if (lowStockProducts.isNotEmpty) {
      print('\n⚠ LOW STOCK ITEMS:');
      lowStockProducts.forEach((p) => print('  $${p.name}: $${p.quantity} left'));
    }
    if (_sales.isNotEmpty) {
      var revenue = _sales.fold(0.0, (s, r) => s + r.total);
      print('\nTotal sales: $${_sales.length}  Revenue: \$$${revenue.toStringAsFixed(2)}');
    }
  }
}

void main() {
  var inv = Inventory();

  inv.addProduct(Product(id: 'P001', name: 'Dart Programming Book', category: 'Books', price: 39.99, quantity: 50));
  inv.addProduct(Product(id: 'P002', name: 'USB-C Cable 2m', category: 'Electronics', price: 12.99, quantity: 120));
  inv.addProduct(Product(id: 'P003', name: 'Mechanical Keyboard', category: 'Electronics', price: 89.99, quantity: 15));
  inv.addProduct(Product(id: 'P004', name: 'Notebook A5', category: 'Stationery', price: 4.99, quantity: 200));
  inv.addProduct(Product(id: 'P005', name: 'Wireless Mouse', category: 'Electronics', price: 34.99, quantity: 8, lowStockThreshold: 10));

  inv.sell('P001', 5);
  inv.sell('P002', 30);
  inv.sell('P005', 3);  // will trigger low stock alert

  inv.restock('P005', 20);
  inv.report();
}

Challenges

• Add supplier management and purchase orders
• Add barcode scanning simulation
• Export inventory to CSV/JSON
• Build a Flutter UI with stock charts