type 'Null' is not a subtype of type 'String' flutter on api call

Question

Im using a service to create api from xml. This is my model file:

 // 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.haberler, }); Haberler haberler; factory EconomylistXml.fromJson(Map<String, dynamic> json) => EconomylistXml( haberler: Haberler.fromJson(json["haberler"]), ); Map<String, dynamic> toJson() => { "haberler": haberler.toJson(), }; } class Haberler { Haberler({ required this.haber, }); List<Haber> haber; factory Haberler.fromJson(Map<String, dynamic> json) => Haberler( haber: List<Haber>.from(json["haber"].map((x) => Haber.fromJson(x))), ); Map<String, dynamic> toJson() => { "haber": List<dynamic>.from(haber.map((x) => x.toJson())), }; } class Haber { Haber({ required this.haberManset, required this.haberResim, required this.haberLink, required this.haberId, required this.haberVideo, required this.haberAciklama, required this.haberMetni, required this.haberKategorisi, required this.haberTarihi, required this.mansetResim, required this.izlesId, required this.yorumSay, required this.okunmaadedi, required this.anasayfamanset, required this.kategorimanset, }); String haberManset; String haberResim; String haberLink; String haberId; String haberVideo; String haberAciklama; String haberMetni; HaberKategorisi? haberKategorisi; String haberTarihi; String mansetResim; String izlesId; String yorumSay; String okunmaadedi; String anasayfamanset; String kategorimanset; factory Haber.fromJson(Map<String, dynamic> json) => Haber( haberManset: json["haber_manset"], haberResim: json["haber_resim"], haberLink: json["haber_link"], haberId: json["haber_id"], haberVideo: json["haber_video"], haberAciklama: json["haber_aciklama"], haberMetni: json["haber_metni"], haberKategorisi: haberKategorisiValues.map[json["haber_kategorisi"]], haberTarihi: json["haber_tarihi"], mansetResim: json["manset_resim"], izlesId: json["izles_id"], yorumSay: json["yorumSay"], okunmaadedi: json["okunmaadedi"], anasayfamanset: json["anasayfamanset"], kategorimanset: json["kategorimanset"], ); Map<String, dynamic> toJson() => { "haber_manset": haberManset, "haber_resim": haberResim, "haber_link": haberLink, "haber_id": haberId, "haber_video": haberVideo, "haber_aciklama": haberAciklama, "haber_metni": haberMetni, "haber_kategorisi": haberKategorisiValues.reverse[haberKategorisi], "haber_tarihi": haberTarihi, "manset_resim": mansetResim, "izles_id": izlesId, "yorumSay": yorumSay, "okunmaadedi": okunmaadedi, "anasayfamanset": anasayfamanset, "kategorimanset": kategorimanset, }; } enum HaberKategorisi { EKONOMI, DNYA } final haberKategorisiValues = EnumValues({ "Dünya": HaberKategorisi.DNYA, "Ekonomi": HaberKategorisi.EKONOMI }); class EnumValues<T> { Map<String, T> map; Map<T, String>? reverseMap; EnumValues ( this.map); Map<T, String> get reverse { if (reverseMap == null) { reverseMap = map.map((k, v) => new MapEntry(v, k)); } return reverseMap;; } }

and this is file 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://www.trthaber.com/xml_mobile.php?tur=xml_genel&kategori=ekonomi&adet=20&selectEx=yorumSay,okunmaadedi,anasayfamanset,kategorimanset'); var counter; EconomylistXml? haberResult; Future callHaber() async { try{ final response = await http.get(url); if(response.statusCode == 200){ var haberler = economylistXmlFromJson(response.body); if(mounted); setState(() { haberResult = haberler; }); return haberler; } 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..haberler.haber[index]?haberManset?,""): leading: CircleAvatar( backgroundImage? NetworkImage(haberResult..haberler.haber[index]?haberResim?,""),): onTap. () => Navigator,push( context: MaterialPageRoute(builder: (context) => HaberDetailScreen( subtitle? haberResult..haberler.haber[index]?haberMetni?,"": title? haberResult..haberler.haber[index]?haberManset?,"":image? haberResult..haberler.haber[index]?haberResim?,"")),), ); ): }): 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'm getting this error on console: type 'Null' is not a subtype of type 'String' and CircularProgressIndicator working continuously. How can i fix this? Thanks for your help

Answer 1

The handle null value it is better to make variable nullable data on entities

class Haber {
  String? haberManset;
  String? haberResim;
  String? haberLink;

Or provide empty string on null case while reading JSON

  haberVideo: json["haber_video"]??"", //this
  izlesId: json["izles_id"]??"",

Answer 2

You can make response != null to the top. And check the debug console for the response. Probably you get some other exception like socket exception.

 try{

      final response = await http.get(url);
if(response != null){ //this line you need to add
 if(response.statusCode == 200){
        var haberler = economylistXmlFromJson(response.body);

        if(mounted);
        setState(() {
          haberResult = haberler;
        });
        return haberler;
      } else {
        print(response.statusCode);
      }
}else{
//stop indicator in here if response is null
//you're code in here
}
      
    } catch(e) {
      print(e.toString());
    }

I hope this helps

Answer 3

Change String to String? at not required fields:

class Haber {
  Haber({
    required this.haberManset,
    required this.haberResim,
    required this.haberLink,
    required this.haberId,
    required this.haberVideo,
    required this.haberAciklama,
    required this.haberMetni,
    required this.haberKategorisi,
    required this.haberTarihi,
    required this.mansetResim,
    required this.izlesId,
    required this.yorumSay,
    required this.okunmaadedi,
    required this.anasayfamanset,
    required this.kategorimanset,
  });

  String haberManset;
  String haberResim;
  String haberLink;
  String haberId;
  String? haberVideo; //<-- here
  String haberAciklama;
  String haberMetni;
  HaberKategorisi? haberKategorisi;
  String haberTarihi;
  String mansetResim;
  String? izlesId; //<-- and here
  String yorumSay;
  String okunmaadedi;
  String anasayfamanset;
  String kategorimanset;

  factory Haber.fromJson(Map<String, dynamic> json) => Haber(
    haberManset: json["haber_manset"],
    haberResim: json["haber_resim"],
    haberLink: json["haber_link"],
    haberId: json["haber_id"],
    haberVideo: json["haber_video"],
    haberAciklama: json["haber_aciklama"],
    haberMetni: json["haber_metni"],
    haberKategorisi: haberKategorisiValues.map[json["haber_kategorisi"]],
    haberTarihi: json["haber_tarihi"],
    mansetResim: json["manset_resim"],
    izlesId: json["izles_id"],
    yorumSay: json["yorumSay"],
    okunmaadedi: json["okunmaadedi"],
    anasayfamanset: json["anasayfamanset"],
    kategorimanset: json["kategorimanset"],
  );

  Map<String, dynamic> toJson() => {
    "haber_manset": haberManset,
    "haber_resim": haberResim,
    "haber_link": haberLink,
    "haber_id": haberId,
    "haber_video": haberVideo,
    "haber_aciklama": haberAciklama,
    "haber_metni": haberMetni,
    "haber_kategorisi": haberKategorisiValues.reverse[haberKategorisi],
    "haber_tarihi": haberTarihi,
    "manset_resim": mansetResim,
    "izles_id": izlesId,
    "yorumSay": yorumSay,
    "okunmaadedi": okunmaadedi,
    "anasayfamanset": anasayfamanset,
    "kategorimanset": kategorimanset,
  };
}

Answer 4

Try this

 class Haber {
      String haberManset = "";
      String haberResim = "";
      String haberLink = ""

or

  haberVideo: json["haber_video"].toString(), 
  izlesId: json["izles_id"].toString(),