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39 lines
1.3 KiB
39 lines
1.3 KiB
5 years ago
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// Copyright 2019 The Flutter team. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'package:flutter/foundation.dart';
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import 'package:provider_shopper/models/catalog.dart';
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class CartModel extends ChangeNotifier {
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/// The current catalog. Used to construct items from numeric ids.
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final CatalogModel _catalog;
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/// Internal, private state of the cart. Stores the ids of each item.
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final List<int> _itemIds;
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/// Construct a CartModel instance that is backed by a [CatalogModel] and
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/// an optional previous state of the cart.
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///
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/// If [previous] is not `null`, it's items are copied to the newly
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/// constructed instance.
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CartModel(this._catalog, CartModel previous)
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: assert(_catalog != null),
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_itemIds = previous?._itemIds ?? [];
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/// List of items in the cart.
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List<Item> get items => _itemIds.map((id) => _catalog.getById(id)).toList();
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/// The current total price of all items.
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int get totalPrice =>
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items.fold(0, (total, current) => total + current.price);
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/// Adds [item] to cart. This is the only way to modify the cart from outside.
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void add(Item item) {
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_itemIds.add(item.id);
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// This line tells [Model] that it should rebuild the widgets that
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// depend on it.
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notifyListeners();
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}
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}
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