Flutter：如果我想导航到详细信息页面，我会在 flutter 中收到无效参数错误

Question

我想导航到详细信息页面。 但我得到无效的参数错误。 在详细页面中，我尝试从我的在线服务器获取详细信息。 如果我单击 android 工作室中的热重载按钮，错误就会消失。 请问，我该如何解决这个错误？ 错误截图

错误日志：

════════ (2) Exception caught by widgets library ═══════════════════════════════════════════════════
Invalid argument(s): The source must not be null
The relevant error-causing widget was: 
  DetailArticlePage file:///C:/Users/abiboo/FlutterProject/projectname/lib/miledoo_widget/home.dart:515:39

//home.dart
return new Container(
          margin: EdgeInsets.symmetric(vertical: 8.0),
          height: 240.0,
          child: ListView.builder(
              scrollDirection: Axis.horizontal,
              itemCount: articledata.length,
              itemBuilder: (BuildContext context,int index) {
                return Padding(
                  padding: EdgeInsets.all(4),
                  child: InkWell(
                    onTap: (){
                      Navigator.push(
                          context,
                          new MaterialPageRoute(
                              builder: (context) =>
                                  DetailArticlePage(int.parse(articledata[index].idArt), articledata[index].designation)));
                    },
                    child: Container(
                      decoration: BoxDecoration(
                        boxShadow: [
                          BoxShadow(

这是详细页面的一段代码，其中包含从服务器获取详细信息的方法

//detailpage.dart
import 'package:cached_network_image/cached_network_image.dart';
import 'package:f_miledoo/miledoo_widget/detail_boutique_page.dart';
import 'package:f_miledoo/miledoo_widget/panier_page.dart';
import 'package:f_miledoo/models/detail_article_models.dart';
import 'package:f_miledoo/models/panier_models.dart';
import 'package:f_miledoo/shared/constants.dart';
import 'package:f_miledoo/utils/database_helper.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import '../localisation_internationnalisation/localisation.dart';
import 'dart:async';
import 'package:http/http.dart' as http;
import 'dart:convert';

class DetailArticlePage extends StatefulWidget{
  final int id_art;
  final String art_desgnation;
  DetailArticlePage(this.id_art, this.art_desgnation);

  DetailArticlePages createState() => DetailArticlePages();
}

class DetailArticlePages extends State<DetailArticlePage> {

  DatabaseHelper helper = DatabaseHelper();
  PanierModel _panier = new PanierModel.withempty();

  final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();



  int qtecompter = 1;
  double prixTotal = 0.0;
  String aAfficher = "";

  int taillePanier = 0;


  String idArt;
  String designation;
  String descrip;
  String prixUnit;
  String prixUnit2;
  String qteStock;
  String idBou;
  String lienPhoto;
  String nomBou;

  @override
  void initState() {
    // TODO: implement initState
    super.initState();

    getpanierTaille();
    this.getRecapArticleData(widget.id_art, widget.art_desgnation);

  }

  getpanierTaille() async => taillePanier = await helper.getCount();





  getRecapArticleData(int id_article, String nom_article) async {
    final response = await http.get(BASE + "xxxxxxx?id_art="+ id_article.toString() +"&nom_art="+ nom_article);
    if (response.statusCode == 200) {
      final jsonResponse = json.decode(response.body);

      TheDetailData myData = new TheDetailData.fromJson(jsonResponse);
      for (var i = 0; i < myData.articledetail.list_recap_article.length; i++) {
        idArt = myData.articledetail.list_recap_article[i].idArt;
        designation = myData.articledetail.list_recap_article[i].designation;
        descrip = myData.articledetail.list_recap_article[i].descrip;
        prixUnit = myData.articledetail.list_recap_article[i].prixUnit;
        prixUnit2 = myData.articledetail.list_recap_article[i].prixUnit2;
        qteStock = myData.articledetail.list_recap_article[i].qteStock;
        lienPhoto = myData.articledetail.list_recap_article[i].lienPhoto;
        idBou = myData.articledetail.list_recap_article[i].idBou;

        print("id_art = " + idArt + " designation = " + designation +
            "  prixUnit2 = " + prixUnit2 + "  Qté = " + qteStock);
      }

    } else {
      throw Exception("Failed to load Data");
    }
  }

  Future<List<ListArtMemeCate>> _getSameArticleData(int id_article, String nom_article) async {
    final response = await http.get(BASE + "xxxxxxx?id_art="+ id_article.toString() +"&nom_art="+ nom_article);
    if (response.statusCode == 200) {
      final jsonResponse = json.decode(response.body);

      TheDetailData myData = new TheDetailData.fromJson(jsonResponse);
      List<ListArtMemeCate> datas = [];

      for (var i = 0; i < myData.articledetail.list_art_meme_cate .length; i++) {
        datas.add(myData.articledetail.list_art_meme_cate[i]);
      }
      return datas;
    } else {
      throw Exception("Failed to load Data");
    }
  }

  @override
  Widget build(BuildContext context) {

    int localStockQte = int.parse(qteStock);
    double localPrixUnit2 = double.parse(prixUnit2.toString());



    Widget article_afficher333 = FutureBuilder(
      future: _getSameArticleData(widget.id_art, widget.art_desgnation),
      builder: (context, snapshot) {
        //if(snapshot.data != null){
        if (snapshot.hasData) {
          List<ListArtMemeCate> articledata = snapshot.data;
          return new Container(
            child: GridView.count(
              shrinkWrap: true,
              crossAxisCount: 2,
              childAspectRatio: 0.7,
              padding: EdgeInsets.only(top: 8, left: 6, right: 6, bottom: 12),
              children: List.generate(articledata.length, (index){
                return Container(
                  child: Card(
                    clipBehavior: Clip.antiAlias,
                    child: InkWell(
                      onTap: () {
                            Navigator.push(
                            context,
                                new MaterialPageRoute(
                                    builder: (context) =>
                                    DetailArticlePage(int.parse(articledata[index].idArt) , articledata[index].designation)));
                      },
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: <Widget>[
                          SizedBox(
                            height: (MediaQuery.of(context).size.width / 2 - 40),
                            width: double.infinity,
                            child: CachedNetworkImage(
                              fit: BoxFit.cover,
                              imageUrl: BASEIMAGES+articledata[index].lienPhoto,
                              placeholder: (context, url) => Center(
                                  child: CircularProgressIndicator()
                              ),
                              errorWidget: (context, url, error) => new Icon(Icons.image),
                            ),
                          ),
                          Padding(
                            padding: const EdgeInsets.only(top: 2.0),
                            child: ListTile(
                              title: Text((() {
                                if(articledata[index].designation.length >12){
                                  return "${articledata[index].designation.substring(0, 12)}...";}

                                return "${articledata[index].designation}";
                              })(), style: TextStyle(fontWeight: FontWeight.bold, fontSize: 15.0, fontFamily: "Questrial")), 
                              subtitle: Column(
                                crossAxisAlignment: CrossAxisAlignment.start,
                                children: <Widget>[
                                  Row(
                                    children: <Widget>[
                                      Padding(
                                        padding: const EdgeInsets.only(top: 2.0, bottom: 1),
                                        child: Text(articledata[index].prixUnit2+" F CFA", style: TextStyle(
                                            color: Theme.of(context).accentColor,
                                            fontWeight: FontWeight.w700,
                                            fontFamily: 'Questrial'
                                        )),
                                      ),
                                    ],
                                  ),

                                ],
                              ),
                            ),
                          )
                        ],
                      ),
                    ),
                  ),
                );
              }),

            ),
          );
        } else if (snapshot.hasError) {
          return Container(
            child: Center(
              child: Text(
                  "Erreur de chargement. Verifier votre connexion internet"),
            ),
          );
        }
        return new Center(
          child: CircularProgressIndicator(),
        );
      },
    );


    setState(() {
      _panier.nom_article = designation;
      _panier.prixUnit2 = double.parse(prixUnit2);
      _panier.image_article = lienPhoto;
      _panier.prixTot = qtecompter*double.parse(prixUnit2);
      _panier.quantite = qtecompter ;
      _panier.id_article = int.parse(idArt);
    });

    void _incrementeQte(){
      setState((){
        if(qtecompter >= localStockQte){
          qtecompter = localStockQte;
        }
        qtecompter++;
      });
    }
    void _decrementeQte(){
      setState((){
        if(qtecompter <=1){
          qtecompter = 1;
        }else{
          qtecompter--;
        }
      });
    }

    String _getPrixTotal(){
      setState((){
        prixTotal = qtecompter*localPrixUnit2;
            aAfficher = prixTotal.toString();
      });
      return aAfficher;
    }
void _ajouterPanier() async {
      //s.addToCart(widget.article);
      var result = await helper.addCart(_panier);
      var result3 = await helper.getCount();
      /*int result;
      result = await helper.addCart(_panier);
      if(result != 0)
        print('STATUS Panier Save Successfully');*/
    }


    return Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(
        title: Text("designation", style:  TextStyle(color: Colors.white),),
        iconTheme: new IconThemeData(color: Colors.white),
        actions: <Widget>[

          Stack(
            children: <Widget>[
              IconButton(
                icon: Icon(Icons.shopping_cart, color: Colors.white, ),
                onPressed: () {
                  //showAlertDialog(context);
                  Navigator.push(context, new MaterialPageRoute(builder: (context) => PanierPage()));
                },
              ),
              Container(
                  width: 25,
                  height: 25,
                  decoration: BoxDecoration(
                    color: Colors.red,
                    borderRadius: BorderRadius.circular(30),
                  ),
                  alignment: Alignment.center,
                  child: Text(taillePanier.toString(),
                    style: TextStyle(
                        color: Colors.white,
                        fontWeight: FontWeight.bold,
                        fontSize: 12
                    ),)
              ),
            ],
          ),
        ],
      ),
      body: new ListView(
        children: <Widget>[
          new Container(
            height: 240,
            child: new Hero(tag: lienPhoto, child: new Material(
              child: InkWell(
                child: new Image.network(
                    BASEIMAGES + lienPhoto,
                    fit: BoxFit.cover),
              ),
            )),
          ),
          new Container(
            child: new Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: <Widget>[
                Padding(
                  padding: const EdgeInsets.only(top: 10,left: 5),
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
                    children: <Widget>[
                      new Text(designation.toString(), style: new TextStyle(fontSize: 20.0, color: Colors.black, fontFamily: 'Questrial'),),
                      ],
                  ),
                ),
                SizedBox(height: 10.0),
                Padding(
                  padding: const EdgeInsets.only(left: 280),
                  child: new Text(prixUnit2.toString()+" F CFA", style: new TextStyle(fontSize: 15.0, color: Colors.black54, fontFamily: 'Questrial', fontWeight: FontWeight.bold),),
                ),

                SizedBox(height: 10.0),
                Padding(
                  padding: const EdgeInsets.only(left: 20, right: 20, bottom: 10),
                  child: new Text(descrip.toString(), style: new TextStyle(fontSize: 15.0, color: Colors.grey, fontFamily: 'Questrial'),),
                ),
                SizedBox(height: 10.0),
                new Container(
                  height: 100,

              child: Column(
                children: <Widget>[
                  Container(
                    height: 1.0,
                    color: Colors.grey,
                  ),
                  Padding(
                    padding: const EdgeInsets.only(left: 25, right: 25, top: 20),
                    child: new Row(
                      mainAxisAlignment: MainAxisAlignment.spaceBetween,
                      children: <Widget>[
                        Text(AppLocalizations.of(context)
                        .translate('_QUANTITY'), style: TextStyle(fontWeight: FontWeight.bold, fontSize: 15, fontFamily: 'Questrial'),),
                        Text(AppLocalizations.of(context)
                            .translate('_TOTAL_PRICE'), style: TextStyle(fontWeight: FontWeight.bold, fontSize: 15, fontFamily: 'Questrial'), ),
                      ],
                    ),
                  ),

                  Padding(
                    padding: const EdgeInsets.only(left: 10, right: 25),
                    child: Row(
                      mainAxisAlignment: MainAxisAlignment.spaceBetween,
                      children: <Widget>[
                        new Row(
                          children: <Widget>[
                            new IconButton(
                              icon: Icon(Icons.remove_circle_outline, color: Colors.amber, ),
                              onPressed: _decrementeQte,
                            ),
                            new Text("$qtecompter"),
                            new IconButton(
                              icon: Icon(Icons.add_circle_outline, color: Colors.amber, ),
                              onPressed: _incrementeQte,
                            ),
                          ],
                        ),
                        new Text(_getPrixTotal()+" F CFA", style: new TextStyle(fontSize: 20.0, color: Colors.grey),),
                      ],
                    ),
                  ),
                  Container(
                    height: 1.0,
                    color: Colors.grey,
                  ),
                ],
              ),
            ),
            //articleMemeCategorie()
          ],
        ),
      ),
      Padding(
        padding: const EdgeInsets.only(top: 10, left: 25, ),
        child: Text(AppLocalizations.of(context)
            .translate('_ITEMS_OF_SAME_QUATEGORY'), style: TextStyle(fontFamily: 'Questrial', fontSize: 15, fontWeight: FontWeight.bold),),
      ),
      article_afficher333,
    ],
  ),
    bottomNavigationBar: new Container(
      color: Colors.white,
      child: new Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: <Widget>[
          Expanded(child: new MaterialButton(
            onPressed: (){showAlertDialog(context);},
            child: new Row(
              //crossAxisAlignment: CrossAxisAlignment.end,
              children: <Widget>[
                IconButton(
            //widget.article
                  icon: Icon(Icons.store, color: Colors.white,),
                  onPressed: () {
                    //showAlertDialog(context);
                    Navigator.push(
                        context,
                        new MaterialPageRoute(
                            builder: (context) =>
                                DetailBoutiquePage(int.parse(idBou)))); },
                ),
              ],
            ),
            color: Color(0xFFFFC23A),
          ),),

          Expanded(
            flex: 2,
            child: new MaterialButton(
            onPressed: (){
              _ajouterPanier();
            },
            child: new Container(
              child: new Row(
                children: <Widget>[
                  IconButton(
                    icon: Icon(Icons.add_shopping_cart, color: Colors.white,),
                  ),
                  Text(AppLocalizations.of(context)
    .translate('_ADD_TO_CART'), style: TextStyle(color: Color(0xFFFFFFFF)))
                ],
              ),
            ),
            color: Color(0xFFFFC23A),
          ),),

          Expanded(child: new MaterialButton(
            onPressed: (){showAlertDialog(context);},
            child: new Text(AppLocalizations.of(context)
                .translate('_BUY_NOW'), style: TextStyle(color: Color(0xFFFFFFFF)),),
            color: Color(0xFFFFC23A),
          ),),
        ],
      ),
    )

);
  }

}

Answer 1

如果没有看到完整的详细信息页面和错误日志，就很难准确判断您的错误是什么。

从您提供的信息看来，您正在尝试从 Http 请求中检索数据，然后使用该信息显示您的页面。 您是否尝试过在详细信息页面中使用 FutureBuilder？ 这将允许您在等待来自服务器的数据时显示一个页面，然后在检索到来自服务器的数据后显示该数据。