*当在代码底部按下添加到购物车按钮时，控制台中会显示一个错误，表明在 null 上调用了 getter 长度。但问题仅存在于单个设备上。我已经在另外 2 台设备上进行了测试。它工作得很好。有没有人对这个问题有任何解决方案？谢谢
类 PrdDetailPage 扩展 StatefulWidget { 最终字符串 PrdID;
const PrdDetailPage({Key key, this.PrdID}) : super(key: key);
@override
_PrdDetailPageState createState() => _PrdDetailPageState(PrdID);
}
class _PrdDetailPageState extends State<PrdDetailPage> {
String _SubCatdropDownValue;
String PrdID;
int _n = 0;
var arrProducts = [];
List arrVarients = List();
var arrImages = [];
var arrProductImages = [];
var ImageList = [];
var strName = "";
var strNos = "";
var thumbnailImage = "";
var varientID = "";
var itemCount = 1;
var strMalaName = "";
var strItemQty = "";
var strDescription = "";
var strMRP = "";
var strSellerID = "";
var strOLD = "";
var isLoading = true;
_PrdDetailPageState(this.PrdID);
@override
void initState() {
super.initState();
this.ProductDetails();
setState(() {});
}
Future<String> ProductDetails() async {
String url = "https://www.clickxpress.in/admin/api/singleproducts";
var rsp = await http.post(Uri.encodeFull(url),
body: (<String, String>{'product_id': PrdID}));
setState(() {
Map<String, dynamic> map = json.decode(rsp.body);
List<dynamic> Data = map["singleproducts"];
arrProducts = Data;
List<dynamic> ImageData = map["sliderimages"];
List<dynamic> varient = map["varients"];
arrVarients = varient;
ImageList = ImageData;
thumbnailImage = arrProducts[0]["thumbnail_image_url"];
strName = arrProducts[0]["product_name"];
strItemQty = arrProducts[0]["int_item_qty"];
strNos = arrProducts[0]["uom"];
strMalaName = arrProducts[0]["product_name_malayalam"];
strDescription = arrProducts[0]["product_description"];
strMRP = arrProducts[0]["product_selling_price"].toString();
strOLD = arrProducts[0]["product_old_price"].toString();
strSellerID = arrProducts[0]["seller_id"].toString();
print("arrProducts");
print(arrProducts);
print("arrProducts");
if (ImageData != null) {
for (var value in ImageData) {
final image = value["image_url"];
arrProductImages.add(NetworkImage(imgUrl + image));
}
}
});
setState(() {
isLoading = false;
});
return "Success";
}
@override
Widget build(BuildContext context) {
return SafeArea(
child: Scaffold(
extendBodyBehindAppBar: true,
appBar: AppBar(
leading: GestureDetector(
onTap: () {
Navigator.pop(context);
},
child: Container(
width: 30,
height: 30,
child: Image.asset(
'assets/images/back.png',
colorBlendMode: BlendMode.color,
scale: 2,
),
),
),
backgroundColor: Colors.transparent,
elevation: 0,
),
body: isLoading == true
? Center(
child: CircularProgressIndicator(),
)
: SingleChildScrollView(
physics: BouncingScrollPhysics(),
child: Column(
children: [
Container(
height: 250,
width: double.infinity,
child: ImageList.isEmpty
? Image(
image: NetworkImage(imgUrl +
arrProducts[0]["thumbnail_image_url"]))
: Carousel(
images: arrProductImages.length != 0
? arrProductImages
: [AssetImage("assets/images/loading.gif")],
autoplay: true,
dotSize: 3,
dotSpacing: 15.0,
dotColor: Colors.purple,
indicatorBgPadding: 5.0,
dotBgColor: Colors.black54.withOpacity(0.0),
moveIndicatorFromBottom: 180.0,
noRadiusForIndicator: true,
),
),
Container(
width: double.infinity,
margin: EdgeInsets.only(left: 10, top: 10, right: 10),
alignment: Alignment.topLeft,
child: Row(
children: [
Expanded(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Text(
strName.toString(),
maxLines: 2,
overflow: TextOverflow.ellipsis,
style: TextStyle(
fontSize: 23,
fontFamily: 'Poppins-Medium'),
),
strItemQty == null
? Opacity(
opacity: 0,
)
: Text(" (" +
strItemQty +
strNos.toString() +
")"),
strMalaName == null
? Opacity(
opacity: 0.0,
)
: Text(strMalaName.toString(),
style: TextStyle(
fontSize: 20,
fontFamily: 'Poppins-Medium',
))
],
),
),
// Spacer(),
Row(
children: [
FavoriteButton(
isFavorite: true,
iconSize: 30,
valueChanged: (_isFavorite) {
print('Is Favorite : $_isFavorite');
},
),
],
),
],
),
),
SizedBox(
height: 10,
),
Container(
margin: EdgeInsets.only(left: 10, right: 10),
width: double.infinity,
child: Row(
// mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
arrVarients.length != 0
? Container(
decoration: BoxDecoration(
border: Border.all(color: Colors.black26),
color: Colors.white,
borderRadius: BorderRadius.circular(05)),
height: 30,
child: Padding(
padding: const EdgeInsets.all(3),
child: DropdownButton<String>(
icon:
Icon(Icons.arrow_drop_down_rounded),
underline: SizedBox(),
hint: _SubCatdropDownValue == null
? Text(
arrVarients[0]['varient_title']
.toString(),
style: TextStyle(fontSize: 15),
)
: Text(_SubCatdropDownValue),
items: arrVarients.map((item) {
return new DropdownMenuItem<String>(
onTap: () {
setState(() {
varientID =
item["id"].toString();
strMRP =
item['varient_new_price']
.toString();
strOLD =
item['varient_old_price']
.toString();
print(varientID);
});
},
value: item['available_varients']
.toString(),
child: new Text(
item['available_varients']
.toString()),
);
}).toList(),
onChanged: (String newValue) {
setState(() {
_SubCatdropDownValue = newValue;
});
},
)),
)
: Opacity(
opacity: 0.0,
),
SizedBox(
width: 10,
),
Column(
children: [
Text(
rs + strMRP,
style: TextStyle(
color: Colors.green,
fontSize: 28,
fontWeight: FontWeight.w700),
)
],
),
SizedBox(
width: 5,
),
// Spacer(),
Text(
rs + strOLD,
style: TextStyle(
color: Colors.black54,
fontSize: 15,
decoration: TextDecoration.lineThrough),
),
SizedBox(
width: 10,
),
Text(
(100 -
((int.parse(arrProducts[0][
"product_selling_price"]
.toString()) /
int.parse(arrProducts[0]
["product_old_price"]
.toString())) *
100))
.round()
.toString() +
"% off",
style:
TextStyle(color: Colors.green, fontSize: 12)),
],
),
),
Divider(
thickness: 1,
color: Colors.grey[200],
endIndent: 20,
indent: 20,
),
strDescription == null
? Opacity(
opacity: 0.0,
)
: Container(
margin: EdgeInsets.all(10),
width: double.infinity,
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Text(
"Details",
style: TextStyle(
fontSize: 20, color: Colors.black54),
),
SizedBox(
height: 5,
),
Text(
strDescription.toString(),
style: TextStyle(
color: Colors.black87,
fontFamily: 'Poppins-Medium',
fontSize: 13,
),
),
Divider(),
],
),
),
SizedBox(
height: 10,
),
],
),
),
bottomNavigationBar: Container(
margin: EdgeInsets.only(
left: 10,
),
height: 50,
width: double.infinity,
child: Row(
children: [
Expanded(
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
SizedBox(
height: 30,
width: 30,
child: new FloatingActionButton(
heroTag: "btn1",
onPressed: () async {
if (itemCount >= 2) {
setState(() => itemCount--);
}
},
child: new Icon(
Icons.remove,
color: Colors.black,
size: 20,
),
backgroundColor: Colors.white,
),
),
new Text(itemCount.toString(),
style: new TextStyle(
fontSize: 20.0, fontWeight: FontWeight.bold)),
SizedBox(
width: 30,
height: 30,
child: new FloatingActionButton(
heroTag: "btn2",
onPressed: () async {
setState(() => itemCount++);
},
child: new Icon(
Icons.add,
color: Colors.black,
size: 20,
),
backgroundColor: Colors.white,
),
),
],
),
),
InkWell(
splashColor: Colors.blue,
onTap: () async {
String url = "https://www.clickxpress.in/admin/api/addtocart";
SharedPreferences prefs =
await SharedPreferences.getInstance();
var strKey = prefs.getString('userKey');
print("__________CART DETAILSS______________");
print("sellerId" + strSellerID);
print("mrp" + strMRP);
print("PRDID" + PrdID);
print(strKey);
print("varID" + varientID);
print(itemCount.toString());
var rsp = await http.post(Uri.encodeFull(url),
body: (<String, String>{
'customer_id': strKey,
'product_id': PrdID,
"seller_id": strSellerID,
'product_qty': itemCount.toString(),
'price': strMRP,
'varient_id': varientID,
}));
setState(
() {
Map<String, dynamic> map = json.decode(rsp.body);
print(map);
if (map["success"] == true) {
Flushbar(
mainButton: FlatButton(
onPressed: () {
Navigator.pushReplacement(
context,
new MaterialPageRoute(
builder: (context) => CartScreen(
PrdQty: itemCount.toString(),
)));
},
child: Text(
"View Cart",
style: TextStyle(color: Colors.white),
),
),
message: map["message"].toString(),
duration: Duration(seconds: 3),
)..show(context);
} else {
Flushbar(
message: map["message"].toString(),
duration: Duration(seconds: 3),
)..show(context);
}
},
);
setState(() {});
},
child: Ink(
height: 50,
width: 150,
decoration: BoxDecoration(
color: Colors.lightBlueAccent,
borderRadius: BorderRadius.circular(5)),
child: Center(
child: Text(
"Add to Cart",
style: TextStyle(color: Colors.white, fontSize: 18),
),
),
),
),
],
),
),
),
);
}
}
答案 0 :(得分：0)
你有这条线：
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@id/tvAppName"
app:layout_constraintHeight_percent="0.35"
app:layout_constraintWidth_percent="0.45"
如果 List<dynamic> varient = map["varients"];
arrVarients = varient;
是 varient，请检查：
null