我有这个流生成器，可以从用户那里选择获取Item并将其显示为订单，
在流构建器中，我可以通过 index 来获得它们，例如snapshot.data.orders[**index**]
当我从流中按一个按钮以将它们保存为 json 字符串并将其作为来自客户的订单发送时，如何获取所有这些数据？
这是代码
import 'package:cosmetics_store/models/Cart.dart';
import 'package:cosmetics_store/bloc/CartBloc.dart';
import 'package:cosmetics_store/components/OrderWidget.dart';
class CartManager extends StatefulWidget {
@override
_CartManager createState() => new _CartManager();
}
class _CartManager extends State<CartManager> {
CartBloc _cartBloc = new CartBloc();
@override
Widget build(BuildContext context) {
double _gridSize = MediaQuery.of(context).size.height * 0.88;
return new Container(
height: MediaQuery.of(context).size.height,
child: new Stack(children: <Widget>[
new Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
new StreamBuilder(
initialData: _cartBloc.currentCart,
stream: _cartBloc.observableCart,
builder: (context, AsyncSnapshot<Cart> snapshot) {
return new Container(
margin: EdgeInsets.symmetric(horizontal: 20),
height: _gridSize,
width: double.infinity,
child: new Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
new Padding(
padding: EdgeInsets.symmetric(vertical: 40),
child: new Text("Cart",
style: TextStyle(
color: Colors.white,
fontSize: 40,
fontWeight: FontWeight.bold))),
new Container(
margin: EdgeInsets.only(bottom: 10),
height: _gridSize * 0.60,
child: new ListView.builder(
itemCount: snapshot.data.orders.length,
itemBuilder: (context, index) {
return Dismissible(
background: Container(
color: Colors.transparent),
key: Key(snapshot
.data.orders[index].id
.toString()),
onDismissed: (_) {
_cartBloc.removerOrderOfCart(
snapshot.data.orders[index]);
},
child: new Padding(
padding: EdgeInsets.symmetric(
vertical: 10),
child: new OrderWidget(
snapshot.data.orders[index],
_gridSize)),
);
})),
new Container(
height: _gridSize * 0.15,
child: new Row(
mainAxisAlignment:
MainAxisAlignment.spaceBetween,
children: <Widget>[
new Text("Total",
style: TextStyle(
color: Colors.white,
fontSize: 20)),
new Text(
"\$${snapshot.data.totalPrice().toStringAsFixed(2)}",
style: TextStyle(
color: Colors.white,
fontWeight: FontWeight.bold,
fontSize: 40)),
]))
]));
})
]),
new Align(
alignment: Alignment.bottomLeft,
child: new Container(
padding: EdgeInsets.only(left: 10, bottom: _gridSize * 0.02),
width: MediaQuery.of(context).size.width - 80,
child: new RaisedButton(
color: Colors.amber,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(60)),
padding: EdgeInsets.all(20),
onPressed: () {
if (_cartBloc.currentCart.isEmpty)
Scaffold.of(context).showSnackBar(
SnackBar(content: Text("Cart is empty")));
else {
}
},
child: new Text("Next",
style: TextStyle(fontWeight: FontWeight.bold)))))
]));
}
}