Listview api white screen return problem flutter

Question

this is my model:

// To parse this JSON data, do
//
//     final economylistXml = economylistXmlFromJson(jsonString);

import 'dart:convert';

EconomylistXml economylistXmlFromJson(String str) => EconomylistXml.fromJson(json.decode(str));

String economylistXmlToJson(EconomylistXml data) => json.encode(data.toJson());

class EconomylistXml {
  EconomylistXml({
    required this.rss,
  });

  Rss rss;

  factory EconomylistXml.fromJson(Map<String, dynamic> json) => EconomylistXml(
    rss: Rss.fromJson(json["rss"]),
  );

  Map<String, dynamic> toJson() => {
    "rss": rss.toJson(),
  };
}

class Rss {
  Rss({
    required this.empty,
    required this.channel,
  });

  Empty empty;
  Channel channel;

  factory Rss.fromJson(Map<String, dynamic> json) => Rss(
    empty: Empty.fromJson(json["\u0024"]),
    channel: Channel.fromJson(json["channel"]),
  );

  Map<String, dynamic> toJson() => {
    "\u0024": empty.toJson(),
    "channel": channel.toJson(),
  };
}

class Channel {
  Channel({
    required this.title,
    required this.link,
    required this.description,
    required this.language,
    required this.copyright,
    required this.image,
    required this.item,
  });

  String? title;
  String? link;
  String? description;
  String? language;
  String? copyright;
  Image image;
  List<Item> item;

  factory Channel.fromJson(Map<String, dynamic> json) => Channel(
    title: json["title"],
    link: json["link"],
    description: json["description"],
    language: json["language"],
    copyright: json["copyright"],
    image: Image.fromJson(json["image"]),
    item: List<Item>.from(json["item"].map((x) => Item.fromJson(x))),
  );

  Map<String, dynamic> toJson() => {
    "title": title,
    "link": link,
    "description": description,
    "language": language,
    "copyright": copyright,
    "image": image.toJson(),
    "item": List<dynamic>.from(item.map((x) => x.toJson())),
  };
}

class Image {
  Image({
    required this.title,
    required this.url,
    required this.link,
    required this.width,
    required this.height,
  });

  String? title;
  String? url;
  String? link;
  String? width;
  String? height;

  factory Image.fromJson(Map<String, dynamic> json) => Image(
    title: json["title"],
    url: json["url"],
    link: json["link"],
    width: json["width"],
    height: json["height"],
  );

  Map<String, dynamic> toJson() => {
    "title": title,
    "url": url,
    "link": link,
    "width": width,
    "height": height,
  };
}

class Item {
  Item({
    required this.title,
    required this.description,
    required this.link,
    required this.pubDate,
  });

  String? title;
  String? description;
  String? link;
  String? pubDate;

  factory Item.fromJson(Map<String, dynamic> json) => Item(
    title: json["title"],
    description: json["description"],
    link: json["link"],
    pubDate: json["pubDate"],
  );

  Map<String, dynamic> toJson() => {
    "title": title,
    "description": description,
    "link": link,
    "pubDate": pubDate,
  };
}

class Empty {
  Empty({
    required this.version,
  });

  String? version;

  factory Empty.fromJson(Map<String, dynamic> json) => Empty(
    version: json["version"],
  );

  Map<String, dynamic> toJson() => {
    "version": version,
  };
}

This is where i call api :

import 'package:flutter/material.dart';
import 'package:halkaarzhisseler/models/apis/economy_api.dart';
import 'package:http/http.dart' as http;

import '../models/apis/economy_xml.dart';
import 'haberdetail.dart';


class Economy extends StatefulWidget {
  const Economy({Key? key}) : super(key: key);

  @override
  State<Economy> createState() => _EconomyState();
}

class _EconomyState extends State<Economy> {
  ScrollController? controller;
  final scaffoldKey = GlobalKey<ScaffoldState>();
  final url = Uri.parse('https://v1.nocodeapi.com/miktadtahir/xml_to_json/htvLvoPDCwIEyTxa?url=https://ekonomigundemi.com.tr/rss/ekonomi/246.xml');
  var counter;
  EconomylistXml? haberResult;

  Future callHaber() async {
    try{

      final response = await http.get(url);

      if(response.statusCode == 200){
        var rss = economylistXmlFromJson(response.body);

        if(mounted);
        setState(() {
          counter = haberResult?.rss.channel.item.length;
          haberResult = rss;
        });
        return rss;
      } else {
        print(response.statusCode);
      }
    } catch(e) {
      print(e.toString());
    }
  }
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    callHaber();
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        centerTitle: false,
        automaticallyImplyLeading: false,
        title: Text(
            'Ekonomi Haberleri'
        ),
      ),
      body: Center(
        child: Padding(
          padding: const EdgeInsets.all(8.0),
          child: counter != null ?

          ListView.builder(
              itemCount: counter,
              itemBuilder: (context, index){
                return Card(
                  child: ListTile(
                    title: Text(haberResult?.rss.channel.item[index].title??""),


                    onTap: () => Navigator.push(
                      context, MaterialPageRoute(builder: (context) => HaberDetailScreen( subtitle: haberResult?.rss.channel.item[index].title??"", title: haberResult?.rss.channel.item[index].description??"")),),
                  ),
                );
              }) : Center(child: CircularProgressIndicator(

          )),
        ),
      ),
    );

  }
}



/*class Economy extends StatefulWidget {
  const Economy({Key? key}) : super(key: key);

  @override
  State<Economy> createState() => _EconomyState();
}

class _EconomyState extends State<Economy> {
  ScrollController? controller;
  final scaffoldKey = GlobalKey<ScaffoldState>();
  final url = Uri.parse('https://api.collectapi.com/news/getNews?country=tr&tag=economy&padding=10');
  var counter;
  Economylist? haberResult;

  Future callHaber() async {
    try{
      Map<String, String> requestHeaders = {
        'Content-Type': 'application/json',
        'Authorization': 'apikey 3fPhNZfVyrl8dOAkT86niI:3g2OzN57bil8vArOdVE3ka'
      };
      final response = await http.get(url,headers:requestHeaders);

      if(response.statusCode == 200){
        var result = economylistFromJson(response.body);

        if(mounted);
        setState(() {
          counter = counter = result.result.length;
          haberResult = result;
        });
        return result;
      } else {
        print(response.statusCode);
      }
    } catch(e) {
      print(e.toString());
    }
  }
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    callHaber();
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        centerTitle: false,
        automaticallyImplyLeading: false,
        title: Text(
            'Ekonomi Haberleri'
        ),
      ),
      body: Center(
        child: Padding(
          padding: const EdgeInsets.all(8.0),
          child: counter != null ?

          ListView.builder(
              itemCount: counter,
              itemBuilder: (context, index){
                return Card(
                  child: ListTile(
                      title: Text(haberResult?.result[index].name??""),
                leading: CircleAvatar(
                backgroundImage: NetworkImage(haberResult?.result[index].image??""),),


                      onTap: () => Navigator.push(
                        context, MaterialPageRoute(builder: (context) => HaberDetailScreen( subtitle: haberResult?.result[index].description??"", title: haberResult?.result[index].name??"",image: haberResult?.result[index].image??"")),),
                  ),
                );
              }) : Center(child: CircularProgressIndicator(

          )),
        ),
      ),
    );

  }
}

 */

I see no error in the console. Only CircularProgressIndicator working. How can i fix this? Thanks for your help

Please read the description of the tags you use. The API tag starts with: DO NOT USE. — user16540390
– user16540390, Commented Aug 19, 2022 at 17:29

Ivo · Accepted Answer · 2022-08-19 11:43:29Z

1

Just switch these two lines:

      counter = haberResult?.rss.channel.item.length;
      haberResult = rss;

to

      haberResult = rss;
      counter = haberResult?.rss.channel.item.length;

You are trying to access haberResult before you assign it

answered Aug 19, 2022 at 11:43

Ivo

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Comments

eamirho3ein · Accepted Answer · 2022-08-19 11:41:45Z

Instead of calling api in initState, you should use FutureBuilder like this:

FutureBuilder(
        future: callHaber(),
        builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return CircularProgressIndicator();
          } else {
            if (snapshot.hasError) {
              return Text('has error');
            } else {
              return ListView.builder(
                  itemCount: counter,
                  itemBuilder: (context, index) {
                    return Card(
                      child: ListTile(
                        title: Text(
                            haberResult?.rss.channel.item[index].title ??
                                ""),
                        onTap: () => Navigator.push(
                          context,
                          MaterialPageRoute(
                              builder: (context) => HaberDetailScreen(
                                  subtitle: haberResult
                                          ?.rss.channel.item[index].title ??
                                      "",
                                  title: haberResult?.rss.channel
                                          .item[index].description ??
                                      "")),
                        ),
                      ),
                    );
                  });
            }
          }
        },
      )

Sabahat Hussain Qureshi · Accepted Answer · 2022-08-19 11:46:09Z

0

Replace callHaber() function with this

Future callHaber() async {
  try{

    final response = await http.get(url);

    if(response.statusCode == 200){
      haberResult = economylistXmlFromJson(response.body);

      if(mounted);
      setState(() {
        counter = haberResult?.rss.channel.item.length;
      });
      return haberResult;
    } else {
      print(response.statusCode);
    }
  } catch(e) {
    print(e.toString());
  }
}

answered Aug 19, 2022 at 11:46

Sabahat Hussain Qureshi

1,3745 silver badges15 bronze badges

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