flutter - http POST リクエストからリストビュー ビルダーにデータを表示する Result Flutter

Question

HTTP POST リクエストの結果からリストビュー ビルダーにデータを表示しようとしましたが、Flutter で結果が表示されましたが、次のエラーが発生しました。

現在、在庫がありませんので、大変助かっております。助けてくれてありがとう。

import 'dart:convert';
import 'dart:io';
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:sunutontine/models/tontine.dart';
import 'package:sunutontine/models/post_result.dart';
import 'package:http/http.dart' as http;
import 'package:sunutontine/utils/constants.dart';
import 'package:sunutontine/pages/cotisation_page.dart';
import 'package:device_info/device_info.dart';

class TontineLanceeListeState extends State<TontineLanceeListe> {
 final globalKey = new GlobalKey<ScaffoldState>();
 List<PostResult> postResult = List();
 PostResult resultFromJson(String str) => 
 PostResult.fromJson(json.decode(str));
 String resultToJson(PostResult data) => json.encode(data.toJson());

 bool _isLoading = false;
 BuildContext context1;


 ListTile _buildItemsForListView(BuildContext context, int index) {
  return ListTile(
        title: Container(
          child: Stack(
          children: <Widget>[
            _semiCircleContainer(),
              _semiCircleContainer(),
              Container(
                padding: EdgeInsets.only(top: 45),
                child: Card(
                  elevation: 3,
                  child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                    children: <Widget>[
                      Padding(padding: EdgeInsets.only(top: 15)),
                      Row(children: <Widget>[Padding(padding: EdgeInsets.only(left: 10)),Text(Texts.CAGNOTTE, style: TextStyle(fontSize: 18.0)), Text(postResult[index].mestontines[index].mtverser, style: TextStyle(color: Colors.orange[900], fontSize: 18.0, fontWeight: FontWeight.bold),)]),
                      Padding(padding: EdgeInsets.all(3)),
                      Divider(),
                      Padding(padding: EdgeInsets.all(3)),
                      Row(children: <Widget>[Padding(padding: EdgeInsets.only(left: 10)), Text(Texts.TONTINE, style: TextStyle(fontSize: 16.0)), Text(postResult[index].mestontines[index].nom, style: TextStyle(color: Colors.grey[900], fontSize: 16.0, fontWeight: FontWeight.bold))]),
                      Padding(padding: EdgeInsets.all(3)),
                      Row(children: <Widget>[Padding(padding: EdgeInsets.only(left: 10)), Text(Texts.MONTANT, style: TextStyle(fontSize: 16.0)), Text(postResult[index].mestontines[index].mtacotiser, style: TextStyle(color: Colors.grey[900], fontSize: 16.0, fontWeight: FontWeight.bold))]),
                      Padding(padding: EdgeInsets.all(3)),
                      Row(children: <Widget>[Padding(padding: EdgeInsets.only(left: 10)), Text(Texts.PERIOD, style: TextStyle(fontSize: 16.0)), Text(postResult[index].mestontines[index].periode, style: TextStyle(color: Colors.grey[900], fontSize: 16.0, fontWeight: FontWeight.bold))]),
                      Padding(padding: EdgeInsets.all(3)),
                      Row(children: <Widget>[Padding(padding: EdgeInsets.only(left: 10)), Text(Texts.DURATION, style: TextStyle(fontSize: 16.0)), Text(postResult[index].mestontines[index].duree, style: TextStyle(color: Colors.grey[900], fontSize: 16.0, fontWeight: FontWeight.bold))]),
                      Padding(padding: EdgeInsets.all(3)),
                      Row(children: <Widget>[Padding(padding: EdgeInsets.only(left: 10)), Text(Texts.START_DATE, style: TextStyle(fontSize: 16.0)), Text(postResult[index].mestontines[index].datedebut, style: TextStyle(color: Colors.grey[900], fontSize: 16.0, fontWeight: FontWeight.bold))]),
                      Padding(padding: EdgeInsets.all(3)),
                      Row(children: <Widget>[Padding(padding: EdgeInsets.only(left: 10)), Text(Texts.END_DATE, style: TextStyle(fontSize: 16.0)), Text(postResult[index].mestontines[index].datefin, style: TextStyle(color: Colors.grey[900], fontSize: 16.0, fontWeight: FontWeight.bold))]),
                      Padding(padding: EdgeInsets.all(3)),
                      Row(
                        children: <Widget>[
                          Padding(padding: EdgeInsets.only(left: 10)), 
                          Text(Texts.STATE, style: TextStyle(fontSize: 16.0)), 
                          Text(postResult[index].mestontines[index].etat, style: TextStyle(color: Colors.grey[900], fontSize: 16.0, fontWeight: FontWeight.bold)),
                          Padding(padding: EdgeInsets.only(left: 60)),
                          Text(Texts.HAND_NUMBER, style: TextStyle(fontSize: 16.0)), Text(postResult[index].mestontines[index].nb, style: TextStyle(color: Colors.grey[900], fontSize: 16.0, fontWeight: FontWeight.bold))]),

                          Padding(padding: EdgeInsets.only(bottom: 10)), 

                          ]
                        ),


                  ),

              ),

              Container(
                padding: EdgeInsets.only(top: 310),
                child: Card(
                  elevation: 5,
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: <Widget>[
                      Padding(padding: EdgeInsets.only(top: 15)),
                      Row(
                        children: <Widget>[
                          Padding(padding: EdgeInsets.only(left: 12)),
                          Text(Texts.NEXT_CASH, style: TextStyle(fontSize: 18.0, color: Colors.orange[900])), 
                          MaterialButton(
                            onPressed: null, 
                            child: Text(Texts.SEE_ALL, style: TextStyle(color: Colors.orange[900], fontSize: 18)),
                            )
                          ]
                        ),
                      Padding(padding: EdgeInsets.all(3)),
                      Divider(),
                      Padding(padding: EdgeInsets.all(3)),
                      Row(
                        children: <Widget>[
                          Padding(padding: EdgeInsets.only(left: 10)),
                          Icon(Icons.calendar_today, color: Colors.orange[900],),
                          Padding(padding: EdgeInsets.only(left: 3)),
                          Text('12 Avril 2020', style: TextStyle(color: Colors.grey, fontSize: 13),) ,
                          Padding(padding: EdgeInsets.only(left: 8)),
                          Container(
                            decoration: BoxDecoration(border: Border.all(color: Colors.red)),
                            child: IconButton(icon: Icon(Icons.search, color: Colors.red,), onPressed: null),
                          ),
                          //Padding(padding: EdgeInsets.only(left: 5)),
                          MaterialButton(
                            onPressed: _goToCotisationScreen,
                            child: Container(
                              decoration: BoxDecoration(border: Border.all(color: Colors.green)),
                              child: Row(
                                children: <Widget>[
                                  IconButton(
                                  icon: Icon(Icons.file_download, color: Colors.green,), 
                                  onPressed: null
                                  ),
                                  Text("COTISER", style: TextStyle(color: Colors.green),),
                                  Padding(padding: EdgeInsets.only(right: 3)),
                                ],
                              )
                              ),
                            ),
                            Padding(padding: EdgeInsets.only(bottom: 5)),
                          ]
                        ),
                        Divider(),
                        Row(
                        children: <Widget>[
                          Padding(padding: EdgeInsets.only(left: 10)),
                          Icon(Icons.calendar_today, color: Colors.orange[900],),
                          Padding(padding: EdgeInsets.only(left: 3)),
                          Text('12 Mai 2020', style: TextStyle(color: Colors.grey, fontSize: 13),) ,
                          Padding(padding: EdgeInsets.only(left: 8)),
                          Container(
                            decoration: BoxDecoration(border: Border.all(color: Colors.red)),
                            child: IconButton(icon: Icon(Icons.search, color: Colors.red,), onPressed: null),
                          ),
                          //Padding(padding: EdgeInsets.only(left: 5)),
                          MaterialButton(
                            onPressed: _goToCotisationScreen,
                            child: Container(
                              decoration: BoxDecoration(border: Border.all(color: Colors.green)),
                              child: Row(
                                children: <Widget>[
                                  IconButton(
                                  icon: Icon(Icons.file_download, color: Colors.green,), 
                                  onPressed: null
                                  ),
                                  Text("COTISER", style: TextStyle(color: Colors.green),),
                                  Padding(padding: EdgeInsets.only(right: 3)),
                                ],
                              )
                              ),
                            ),
                            Padding(padding: EdgeInsets.only(bottom: 5)),
                          ]
                        ),
                        Padding(padding: EdgeInsets.only(top: 15)),
                        Divider(),
                        Row(
                          children: <Widget>[
                            Padding(padding: EdgeInsets.only(left: 12)),
                            Text(Texts.TEGGI, style: TextStyle(fontSize: 18.0, color: Colors.green)),
                            Padding(padding: EdgeInsets.only(left: 80)), 
                            MaterialButton(
                              onPressed: null, 
                              child: Text(Texts.SEE_ALL, style: TextStyle(color: Colors.green, fontSize: 18)),
                              )
                            ]
                          ),
                          Divider(),
                          Row(
                        children: <Widget>[
                          Padding(padding: EdgeInsets.only(left: 10)),
                          Icon(Icons.calendar_today, color: Colors.green,),
                          Padding(padding: EdgeInsets.only(left: 3)),
                          Text('12 juin 2020 \nSokhna Khady Ngom', style: TextStyle(color: Colors.grey, fontSize: 18),) ,
                          //Padding(padding: EdgeInsets.only(left: 5)),

                            Padding(padding: EdgeInsets.only(bottom: 5)),
                          ]
                        ),
                        Divider(),
                          Row(
                        children: <Widget>[
                          Padding(padding: EdgeInsets.only(left: 10)),
                          Icon(Icons.calendar_today, color: Colors.green,),
                          Padding(padding: EdgeInsets.only(left: 3)),
                          Text('12 juin 2020 \nSokhna Khady Ngom', style: TextStyle(color: Colors.grey, fontSize: 18),) ,
                          //Padding(padding: EdgeInsets.only(left: 5)),

                            Padding(padding: EdgeInsets.only(bottom: 5)),
                          ]
                        ),
                    ],
                  ),
                ),
              )
            ],
          ),
        ),

  );
}

 Future<bool> _onWillPop() {
 return showDialog(
   context: context,
   builder: (context) => AlertDialog(
     elevation: 10,
     backgroundColor: Colors.orange[900],
     content: Text("Voulez-vous vraiment\n quitter SunuTontine ?", style: TextStyle(color: Colors.white)),
     actions: <Widget>[
       FlatButton(
         shape: Border.all(color: Colors.white),
         onPressed: () => Navigator.of(context).pop(false),
         child: Text('NON', style: TextStyle(color: Colors.white)),
       ),
       Padding(padding: EdgeInsets.only(left: 60)),
       FlatButton(
         color: Colors.white,
         shape: Border.all(color: Colors.white),
         onPressed: () => exit(0),
        /*Navigator.of(context).pop(true)*/
        child: Text('OUI', style: TextStyle(color: Colors.orange[900])),
       ),
     ],
   ),
 ) ??
     false;
 }

 @override
 Widget build(BuildContext context) {
  return WillPopScope(
   child: Scaffold(
     key: globalKey,
     body: _isLoading ? CircularProgressIndicator() : ListView.builder(
       itemCount: postResult == null ? 0 : postResult.length,
       itemBuilder: _buildItemsForListView,
      )
    ), 
    onWillPop: _onWillPop);
 }


 Future<String> getData() async {
   var uuid = await _getId();
   var reqestData = {'uuid':uuid, 'idclient': widget.id };

    var response = await http.post(
    "https://numherit-labs.com/sunutontine/ScriptMobileEtontine/tontineslancees.php",
    body: reqestData,

   );

   var message = jsonDecode(response.body);

   if(response.statusCode == 200 && message['statut'] == 'OK'){
   print(message);
   return message;

   }
   else{
    return message;
   }
 }

Future loadData() async {
// var uuid = await _getId();
 print(widget.id);

  setState(() {
    _isLoading = true;
 });

 String jsonString = await getData();
 final result = resultFromJson(jsonString);
 postResult.add(result);

 setState(() {
    _isLoading = false;
   });
 }

  @override
  void initState() {
   super.initState();

   loadData();
  }

  Future<String> _getId() async {
   DeviceInfoPlugin deviceInfo = DeviceInfoPlugin();
   if (Theme.of(context).platform == TargetPlatform.iOS) {
     return iosDeviceInfo.identifierForVendor; // unique ID on iOS
   } else {
     AndroidDeviceInfo androidDeviceInfo = await deviceInfo.androidInfo;
     return androidDeviceInfo.androidId; // unique ID on Android
   }
 }
     ///////////////////////////////////////////////////////////////////////
 Widget _semiCircleContainer() {
 return new Container(
     width: 100.0,
     height: 100.0,
     margin: EdgeInsets.only(left: 110.0, top: 30.0),
     decoration: mySemiCircleDecoration(),

     );
 }

 BoxDecoration mySemiCircleDecoration() {
  return BoxDecoration(
    borderRadius: BorderRadius.circular(300.0),
    //shape: BoxShape.circle,
    color: Colors.white,
  );
 }

 void _goToCotisationScreen(){
   Navigator.pushReplacement(
    context,
    new MaterialPageRoute(builder: (context) => CotisationPage()),
   );
  }

}

class TontineLanceeListe extends StatefulWidget {
 TontineLanceeListe({Key key, this.id}) : super(key: key);
 int id;


 @override
 createState() => TontineLanceeListeState(); 
}

ここに私のモデルがあります:

tontines.dart

class Tontine {
 String id;
 String nom;
 String code;
 String nbmax;
 String nbmin;
 String nb;
 String periode;
 String mtacotiser;
 String tontinier;
 String duree;
 String dateprevue;
 String datedebut;
 String postecash;
 String etat;
 String etattirage;
 String mtverser;
 DateTime datecreation;
 String usercreation;
 String datemodif;
 String usermodif;
 String modetirage;
 String description;
 String datecotise;
 String datefin;

 Tontine(
    {this.id,
    this.nom,
    this.code,
    this.nbmax,
    this.nbmin,
    this.nb,
    this.periode,
    this.mtacotiser,
    this.tontinier,
    this.duree,
    this.dateprevue,
    this.datedebut,
    this.postecash,
    this.etat,
    this.etattirage,
    this.mtverser,
    this.datecreation,
    this.usercreation,
    this.datemodif,
    this.usermodif,
    this.modetirage,
    this.description,
    this.datecotise,
    this.datefin});

factory Tontine.fromJson(Map<String, dynamic> json) {
   return Tontine(
    id : json['id'],
    nom : json['nom'],
    code : json['code'],
    nbmax : json['nbmax'],
    nbmin : json['nbmin'],
    nb : json['nb'],
    periode : json['periode'],
    mtacotiser : json['mtacotiser'],
    tontinier : json['tontinier'],
    duree : json['duree'],
    dateprevue : json['dateprevue'],
    datedebut : json['datedebut'],
    postecash : json['postecash'],
    etat : json['etat'],
    etattirage : json['etattirage'],
    mtverser : json['mtverser'],
    datecreation : json['datecreation'],
    usercreation : json['usercreation'],
    datemodif : json['datemodif'],
    usermodif : json['usermodif'],
    modetirage : json['modetirage'],
    description : json['description'],
    datecotise : json['datecotise'],
    datefin : json['datefin']
    );
  }



 Map<String, dynamic> toJson() {
  final Map<String, dynamic> data = new Map<String, dynamic>();
    data['id'] = this.id;
    data['nom'] = this.nom;
    data['code'] = this.code;
    data['nbmax'] = this.nbmax;
    data['nbmin'] = this.nbmin;
    data['nb'] = this.nb;
    data['periode'] = this.periode;
    data['mtacotiser'] = this.mtacotiser;
    data['tontinier'] = this.tontinier;
    data['duree'] = this.duree;
    data['dateprevue'] = this.dateprevue;
    data['datedebut'] = this.datedebut;
    data['postecash'] = this.postecash;
    data['etat'] = this.etat;
    data['etattirage'] = this.etattirage;
    data['mtverser'] = this.mtverser;
    data['datecreation'] = this.datecreation;
    data['usercreation'] = this.usercreation;
    data['datemodif'] = this.datemodif;
    data['usermodif'] = this.usermodif;
    data['modetirage'] = this.modetirage;
    data['description'] = this.description;
    data['datecotise'] = this.datecotise;
    data['datefin'] = this.datefin;
     return data;
   }
  }

post_result.dart

import 'tontine.dart';

class PostResult {
  String statut;
  int errorCode;
  String errorMessage;
  List<Tontine> mestontines;

  PostResult({
    this.statut,
    this.errorCode,
    this.errorMessage,
    this.mestontines,
  });

 factory PostResult.fromJson(Map<String, dynamic> json) => PostResult(
      statut: json["responseCode"],
      errorCode: json["errorCode"],
      errorMessage: json["errorMessage"],
      mestontines: List<Tontine>.from(
         json["mestontines"].map((x) => Tontine.fromJson(x))),
     );

 Map<String, dynamic> toJson() => {
      "responseCode": statut,
      "errorCode": errorCode,
      "errorMessage": errorMessage,
      "mestontines": List<dynamic>.from(mestontines.map((x) => x.toJson())),
    };

}

そして、私の投稿リクエストは次のようなものを返します:

{
  "statut":"OK",
  "errorCode":0,
  "errorMessage":"",
  "mestontines":[
    {
      "id":"1",
      "nom":"test tontine",
      "code":"TNE-5994945946",
      "nbmax":"3",
      "nb":"2",
      "nbmin":null,
      "periode":"30",
      "mtacotiser":"10000",
      "tontinier":"1439",
      "duree":"3",
      "dateprevue":"2020-01-10",
      "datedebut":"2017-11-21",
      "postecash":"00221775373761",
      "etat":"1",
      "etattirage":"0",
      "mtverser":"0",
      "modetirage":"1",
      "description":"",
      "datecotise":"20",
      "periodicite":"Mensuelle",
      "libmodetirage":"Al\u00e9atoire",
      "enattente":1,
      "idperiodicite":"4"
    }
  ]
 }