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我没有出错，但问题是当我获取下一个 10 条记录然后记录来打印logcat但在SliverList记录中没有添加到列表中，我不知道到底是什么问题，数据来了并更新列表，然后突然回到他之前的列表长度状态，意味着当我尝试fetchmore方法时，列表长度更新为 10 到 20，突然又回到 10，所以请帮我解决这个问题。

  @override
void initState() {
super.initState();
_controller = ScrollController();
_controller.addListener(_scrollListener);
loadMyProduct();


}
  _scrollListener() {
if (_controller.offset >= _controller.position.maxScrollExtent &&
    !_controller.position.outOfRange) {

  fetchMoreProduct(listProduct.length+1);
}
if (_controller.offset <= _controller.position.minScrollExtent &&
    !_controller.position.outOfRange) {
  setState(() {
    print("at top");
  });
}


}



bool isMoreRunning=false;
  fetchMoreProduct(int newLength)async{
    //if(isMoreRunning==false && totalProducts>newLength){
      print("new length  "+newLength.toString());
        isMoreRunning=true;
    visibleMore=true;

    print(totalProducts);

  var url="http://ochapchap.com/api/productList";
  SharedPreferences prefs = await SharedPreferences.getInstance();

  String  userid=prefs.getString('userid');
  var data = {
    "startLimit":newLength.toString(),
    "language":"en",
    "userId":userid};
  var response = await http.post(url, body: json.encode(data));

  if(response.statusCode==200) {
    FeedCheckProduct checkLogin =FeedCheckProduct.fromJson(json.decode(response.body));

    if(checkLogin.success==1){
      List<FeedProduct> newProduct=(jsonDecode(response.body)['result'] as List).map((i) => FeedProduct.fromJson(i)).toList();

      newProduct.forEach((element) async{
          print(element.name+" "+element.price);
          listProduct.add(element);
      });
      print("NEW PRODUCT LENGTH  "+listProduct.length.toString());
      setState(() {
        listProduct.length;
      });
        visibleMore=false;
    }
  /*}else{
    setState(() {
      isMoreRunning=false;
      isProductLoad=false;
      visibleMore=false;
    });
    Fluttertoast.showToast(
        msg: "Try after some time!.",
        toastLength: Toast.LENGTH_SHORT,
        gravity: ToastGravity.CENTER,
        timeInSecForIosWeb: 1,
        backgroundColor: Colors.red,
        textColor: Colors.white,
        fontSize: 16.0
    );
  }*/
}
}

Future<List<FeedProduct>> loadProduct()async{
Future.delayed(const Duration(seconds: 3));

setState(() {
  isProductLoad=true;
});
Map<String, String> requestHeaders = {
  'Content-type': 'application/json',
  'Accept': 'application/json',
};
var url="http://ochapchap.com/api/productList";
SharedPreferences prefs = await SharedPreferences.getInstance();

String  userid=prefs.getString('userid');
String language=prefs.getString('language');
if(language==null){
  language="en";
}
var data = {
  "startLimit":"0",
  "language": language,
  "userId":userid};

var response = await http.post(url, body: json.encode(data),headers: requestHeaders);
if(response.statusCode==200) {
  FeedCheckProduct checkLogin =FeedCheckProduct.fromJson(json.decode(response.body));
  setState(() {
    totalProducts=checkLogin.totalCount;
  });
  if(checkLogin.success==1){
    Map<String, dynamic> mainData=json.decode(response.body);
    listProduct=(jsonDecode(response.body)['result'] as List).map((i) => FeedProduct.fromJson(i)).toList();
    print("rrrrrrrrrrrrrrrrrrrr "+listProduct.length.toString());
    return listProduct;
  }
}else{
  setState(() {
    isProductLoad=false;
  });
}


}
 
@override
  void dispose() {
    super.dispose();
    _controller.dispose();
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: ShowProduct(),
    );
  }
Widget ShowProduct(){
  return Column(
    children: <Widget>[
      Expanded(
        child: FutureBuilder(
          future: loadProduct(),
          builder: (BuildContext context,AsyncSnapshot snapshot) {
            if (snapshot.hasData) {
              return CustomScrollView(
                controller: _controller,
                slivers: <Widget>[
                  SliverAppBar(
                    title: Text("Home"),
                    floating: true,
                  ),
                  SliverList(
                    delegate: SliverChildBuilderDelegate(
                        (BuildContext context, int index){
                            return ProductList(
                              product:listProduct[index], index: index,);

                        },
                      childCount: listProduct.length,
                    ),
                  ),
                ],
              );
   Visibility(
        visible: visibleMore,
        child: Padding(
          padding: const EdgeInsets.fromLTRB(0.0, 8.0, 0.0, 30.0),
          child: new CircularProgressIndicator(),
        ),
      )
    ],
  );

}

4

1 回答 1

-1

https://stackoverflow.com/a/61392563/13608248有更好的答案，或者不要使用 FutureBuilder，因为它代表您的存储库收到的数据。该过程应该是显示初始数据 -> 调用下一个 N 数据 -> N 条记录应该添加到同一个列表 -> 父小部件应该通知列表更新（即通过 setState）

于 2020-08-30T19:35:20.807 回答