如何解决难以将商品添加到购物车-Flutter
我的Cart模型如下所示
class Cart {
String description;
double unitCost;
double amount;
int quantity;
String color;
String imageURl;
Cart({
this.description,this.unitCost,this.amount,this.color,this.quantity,this.imageURl,});
}
还有我的CartData通知程序类，该类具有一个_cartList并预加载了数据，如下所示：
class CartData extends ChangeNotifier {
List<Cart> _cartItems = [
Cart(
imageURl:
'https://s2.r29static.com/bin/entry/ebd/0,675,2000,1050/x,80/1929471/image.jpg',description: 'Nike Air Max',quantity: 3,unitCost: 6000,),Cart(
color: 'red',unitCost: 3000,Cart(
imageURl:
'https://s2.r29static.com/bin/entry/ebd/0,quantity: 6,Cart(
color: 'purple',quantity: 2,unitCost: 1000,unitCost: 2000,];
UnmodifiableListView<Cart> get cartItems {
return UnmodifiableListView(_cartItems);
}
int get cartItemsCount {
return _cartItems.length;
}
void addItemToCart(
String color,double unitCost,String description,String imageURL,int quantity,) {
_cartItems.insert(
0,Cart(
color: color,unitCost: unitCost,description: description,imageURl: imageURL,quantity: quantity,);
notifyListeners();
}
void getTotalSum(Cart cart) {}
double getAmount(int qty,double unitCost) {
return qty * unitCost;
}
void upDateCartItem(Cart cartItem,bool isIncrementing) {
if (isIncrementing == true) {
cartItem.quantity++;
print(
'Cart item purchase quantity is: ${cartItem.quantity},after incrementing from updateCartItem');
} else {
if (cartItem.quantity >= 1) {
cartItem.quantity--;
print(
'Cart item purchase quantity is: ${cartItem.quantity} after decrementing from updateCartItem');
}
if (cartItem.quantity == 0) {
deleteItemFromCart(cartItem);
}
print(cartItem.quantity);
}
cartItem.amount = cartItem.quantity * cartItem.unitCost;
print('Cart Item amount is: ${cartItem.amount} from updateCartItem');
notifyListeners();
}
void deleteItemFromCart(Cart cartItem) {
_cartItems.remove(cartItem);
notifyListeners();
}
}
我希望能够使用addItemToCart()方法将商品快速添加到现有的购物车清单中，并立即在购物车页面上显示它们。
在我的购物屏幕中，我有一些声明如下：
String defaultDescription = 'add description';
String paymentDescription = 'add description';
String amount = '0';
int cartTotal = 0;
但是，当我按如下所示调用addItemToCart方法时，无法从购物屏幕中将商品添加到购物车中：
_addToCart() {
if (amount == '' || amount == '0') {
print('add an amount');
_showToast(this.context,'amount');
} else if (paymentDescription == defaultDescription) {
print('please enter a valid description to proceed');
_showToast(this.context,'payment description');
} else {
print(amount);
print(paymentDescription);
//do something like add to cart
CartData cartData = Provider.of<CartData>(context,listen: false);
cartData.addItemToCart(
null,double.parse(output),paymentDescription,null,1,);
}
setState(() {
paymentDescription = defaultDescription;
amount = '0';
});
}
这是我的结帐屏幕，显示购物车中的物品：
class CheckoutScreen extends StatefulWidget {
static const String id = 'checkout_screen';
@override
_CheckoutScreenState createState() => _CheckoutScreenState();
}
class _CheckoutScreenState extends State<CheckoutScreen> {
@override
void initState() {
super.initState();
CustomerNotifier customerNotifier =
Provider.of<CustomerNotifier>(context,listen: false);
customerNotifier.getCustomers(customerNotifier);
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: ChangeNotifierProvider(
create: (context) => CartData(),child: Consumer<CartData>(
builder: (context,cartData,child) {
return Column(
children: <Widget>[
Row(
children: <Widget>[
IconButton(
icon: Icon(
Icons.arrow_back_ios,color: Colors.black26,onPressed: () => Navigator.pop(context),Text(
'Shopping cart',style: TextStyle(
fontSize: 21.0,fontWeight: FontWeight.bold,],Container(
margin: EdgeInsets.only(top: 8.0,bottom: 8.0),height: MediaQuery.of(context).size.height / 16,width: MediaQuery.of(context).size.width - 150,decoration: BoxDecoration(
border: Border.all(color: kThemeStyleButtonFillColour),borderRadius: BorderRadius.circular(5.0),child: Row(
crossAxisAlignment: CrossAxisAlignment.center,mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[
Text(
'Customer drop down',textAlign: TextAlign.center,style: kRegularTextStyle,maxLines: 2,textDirection: TextDirection.ltr,softWrap: true,SizedBox(width: 5.0),Icon(
Icons.keyboard_arrow_down,color: kThemeStyleButtonFillColour,size: 25,Expanded(
flex: 4,child: Container(
height: MediaQuery.of(context).size.height - 225,padding: const EdgeInsets.only(
left: 16,right: 16,child: ListView.builder(
itemCount: cartData.cartItems.length,shrinkWrap: true,itemBuilder: (context,index) {
final cartItem = cartData.cartItems[index];
return cartData.cartItems.isEmpty
? Container(
child: Align(
alignment: Alignment.center,child: Text('Your cart is empty')))
: Container(
color: Colors.white,margin: EdgeInsets.symmetric(vertical: 6.0),child: Row(
children: <Widget>[
Expanded(
child: Container(
width: 80.0,height: 70.0,child: Center(
child: cartItem.imageURl == null
? Container(
padding:
EdgeInsets.all(4.0),decoration: BoxDecoration(
color: Color((math.Random()
.nextDouble() *
0xFFFFFF)
.toInt())
.withOpacity(1.0),borderRadius:
BorderRadius.circular(
20.0),)
: Container(
padding:
EdgeInsets.all(4.0),decoration: BoxDecoration(
image: DecorationImage(
fit: BoxFit.cover,image: NetworkImage(
cartItem.imageURl),SizedBox(width: 12.0),Column(
crossAxisAlignment:
CrossAxisAlignment.start,children: <Widget>[
Container(
width: 100.0,child: Text(
cartItem.description,style: TextStyle(
fontWeight: FontWeight.bold),SizedBox(height: 8.0),Row(
children: <Widget>[
GestureDetector(
child: Container(
width: 20.0,height: 20.0,decoration: BoxDecoration(
color: Colors.grey[200],borderRadius:
BorderRadiusDirectional
.circular(4.0),child: Icon(
Icons.remove,color: Colors.white,size: 15.0,onTap: () {
cartData.upDateCartItem(
cartItem,false);
},Padding(
padding:
const EdgeInsets.symmetric(
horizontal: 15.0),child: Text(
'${cartItem.quantity}',style: TextStyle(
fontWeight:
FontWeight.bold,fontSize: 15.0),GestureDetector(
child: Container(
width: 20.0,decoration: BoxDecoration(
color:
kThemeStyleButtonFillColour,child: Icon(
Icons.add,true);
},// Spacer(),Expanded(
child: Text(
'${cartData.getAmount(cartItem.quantity,cartItem.unitCost)}',style: TextStyle(
fontWeight: FontWeight.bold,Expanded(
child: GestureDetector(
child: Icon(
Icons.delete_forever,size: 25.0,onTap: () => cartData
.deleteItemFromCart(cartItem),);
},);
},);
}
}
我在这里想念什么？
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