flutter_fooddelivery/lib/model/tableDetail.dart

import 'package:collection/collection.dart' show IterableExtension;
import 'package:flutter/cupertino.dart';
import 'package:fooddeliveryapp/model/product.dart';

class Item {
  int? count;
  Product? product;

  Item(int i, Product? p) {
    this.count = i;
    product = p;
  }
}

class TableDetail with ChangeNotifier {
  //记录当前使用台号
  int? _tableId;

  DateTime? openTime;

  TableDetail({int? id}) {
    this._tableId = id;
    notifyListeners();
  }

  List<Item> _items = [];

  List<Item> get items => _items;

  int? getTableId() => _tableId;

  DateTime? getOpenTime() => openTime;

  setTableId(int id) {
    print("[tabledetails]设置桌号id" + id.toString());
    this._tableId = id;
    this.openTime = DateTime.now();
    notifyListeners();
  }

  addItem(Product? p) {
    Item? item = _items.firstWhereOrNull((i) => i.product == p);
    if (item == null) {
      item = Item(0, p);
      _items.add(item);
    }
    if (item.count != null) {
      item.count = item.count! + 1;
    }
    notifyListeners();
  }

  // 从购物车移除商品，判断数量，通知
  removeItem(Product? p) {
    Item? item = _items.firstWhereOrNull((i) => i.product == p);
    if (item == null) {
      return;
    }
    if (item.count != null) {
      item.count = item.count! - 1;
    }
    if (item.count == 0) {
      _items.remove(item);
    }
    notifyListeners();
  }

  endCart() {
    _items = [];
  }

  // 获取购物车中指定商品数量，不存在返回0
  int? getItemCount(Product? p) {
    Item? item = _items.firstWhereOrNull((i) => i.product == p);
    return item == null ? 0 : item.count;
  }

  // 计算总总额。取小数点2位转字符串
  String getTotalPrices() {
    double total = 0;
    for (var item in _items) {
      total += item.product!.price! * item.count!;
    }
    return total.toStringAsFixed(2);
  }
}