FormatException:unexpected Character flutter - flutter

Question

i tried to decode my json and take the values to futurebuilder in flutter when decode my json appear formatexception:unexpectedcharacter,tried to storage in a String and in List, think my error think is how to toke data,how to storage my json decode,
Thanks
my code
import 'dart:convert';
import 'package:http/http.dart' as http;
import 'package:oauth2_client/spotify_oauth2_client.dart';
import 'package:ui/Models/segundapantalla.dart';
import 'newmodel.dart';
class callttoappi {
Future getatatodapi() async {
String url =
'https://api.spotify.com/v1/playlists/37i9dQZF1DXcBWIGoYBM5M/tracks';
var client = SpotifyOAuth2Client(
redirectUri: 'com.example.ui://callback',
customUriScheme: 'com.example.ui');
var tknResp = await client.getTokenWithAuthCodeFlow(
clientId: 'client id',
scopes: [
'user-read-email',
'user-read-private',
]);
if (tknResp != null) {
var headers = {
'Authorization': 'Bearer ${tknResp.accessToken}',
};
var request = await http.Request(
'GET', Uri.parse('https://api.spotify.com/v1/browse/new-releases'));
request.headers.addAll(headers);
http.StreamedResponse response =
await request.send().timeout(const Duration(seconds: 20));
if (response.statusCode == 200) {
//String reponsedata = await response.stream.bytesToString();
//print(await response.stream.bytesToString());
Map<String, dynamic> userMap = jsonDecode(await response.stream.bytesToString());
var user = Item.fromJson(userMap);
print(userMap);
//Map<String,dynamic> json = jsonDecode(await response.stream.bytesToString());
//print(json);
return Item.fromJson(jsonDecode(json.toString()));
} else {
print(response.reasonPhrase);
}
}
}
}
my model class,quicktype website or another page this like github projects to obtain my json
class Newmodel {
Newmodel({
required this.albums,
});
final Albums? albums;
factory Newmodel.fromJson(Map<String, dynamic> json){
return Newmodel(
albums: json["albums"] == null ? null : Albums.fromJson(json["albums"]),
);
}
Map<String, dynamic> toJson() => {
"albums": albums?.toJson(),
};
#override
String toString(){
return '$albums';
}
}
class Albums {
Albums({
required this.href,
required this.items,
required this.limit,
required this.next,
required this.offset,
required this.previous,
required this.total,
});
final String? href;
final List<Item> items;
final int? limit;
final String? next;
final int? offset;
final dynamic previous;
final int? total;
factory Albums.fromJson(Map<String, dynamic> json){
return Albums(
href: json["href"],
items: json["items"] == null ? [] : List<Item>.from(json["items"]!.map((x) => Item.fromJson(x))),
limit: json["limit"],
next: json["next"],
offset: json["offset"],
previous: json["previous"],
total: json["total"],
);
}
Map<String, dynamic> toJson() => {
"href": href,
"items": List<Item>.from(items.map((x) => x.toJson())),
"limit": limit,
"next": next,
"offset": offset,
"previous": previous,
"total": total,
};
#override
String toString(){
return '$href, $items, $limit, $next, $offset, $previous, $total';
}
}
class Item {
Item({
required this.albumType,
required this.artists,
required this.availableMarkets,
required this.externalUrls,
required this.href,
required this.id,
required this.images,
required this.name,
required this.releaseDate,
required this.releaseDatePrecision,
required this.totalTracks,
required this.type,
required this.uri,
});
final String? albumType;
final List<Artist> artists;
final List<String> availableMarkets;
final ExternalUrls? externalUrls;
final String? href;
final String? id;
final List<Image> images;
final String? name;
final DateTime? releaseDate;
final String? releaseDatePrecision;
final int? totalTracks;
final String? type;
final String? uri;
factory Item.fromJson(Map<String, dynamic> json){
return Item(
albumType: json["album_type"],
artists: json["artists"] == null ? [] : List<Artist>.from(json["artists"]!.map((x) => Artist.fromJson(x))),
availableMarkets: json["available_markets"] == null ? [] : List<String>.from(json["available_markets"]!.map((x) => x)),
externalUrls: json["external_urls"] == null ? null : ExternalUrls.fromJson(json["external_urls"]),
href: json["href"],
id: json["id"],
images: json["images"] == null ? [] : List<Image>.from(json["images"]!.map((x) => Image.fromJson(x))),
name: json["name"],
releaseDate: json["release_date"] == null ? null : DateTime.parse(json["release_date"]),
releaseDatePrecision: json["release_date_precision"],
totalTracks: json["total_tracks"],
type: json["type"],
uri: json["uri"],
);
}
Map<String, dynamic> toJson() => {
"album_type": albumType,
"artists": List<Artist>.from(artists.map((x) => x.toJson())),
"available_markets": List<String>.from(availableMarkets.map((x) => x)),
"external_urls": externalUrls?.toJson(),
"href": href,
"id": id,
"images": List<Image>.from(images.map((x) => x.toJson())),
"name": name,
//"release_date": "${releaseDate.year.toString().padLeft(4'0')}-${releaseDate.month.toString().padLeft(2'0')}-${releaseDate.day.toString().padLeft(2'0')}",
"release_date_precision": releaseDatePrecision,
"total_tracks": totalTracks,
"type": type,
"uri": uri,
};
#override
String toString(){
return '$albumType, $artists, $availableMarkets, $externalUrls, $href, $id, $images, $name, $releaseDate, $releaseDatePrecision, $totalTracks, $type, $uri';
}
}
viewpage class
class lodeo extends StatefulWidget {
#override
State<lodeo> createState() => _WeatherPageState();
}
class _WeatherPageState extends State<lodeo> {
Future getData() async {
return await callttoappi().getatatodapi();
}
Future<dynamic>? _myData;
#override
void initState() {
setState(() {
_myData = getData();
});
super.initState();
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: FutureBuilder(
builder: (ctx, snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
// If error occured
if (snapshot.hasError) {
return Center(
child: Text(
'${snapshot.error.toString()} occurred',
style: TextStyle(fontSize: 18),
),
);
// if data has no errors
} else if (snapshot.hasData) {
// Extracting data from snapshot object
final data = snapshot.data as Item;
return Container(
padding: EdgeInsets.symmetric(horizontal: 15, vertical: 10),
decoration: const BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topLeft,
end: Alignment(0.8, 1),
colors: <Color>[
Color.fromARGB(255, 65, 89, 224),
Color.fromARGB(255, 83, 92, 215),
Color.fromARGB(255, 86, 88, 177),
Color(0xfff39060),
Color(0xffffb56b),
],
tileMode: TileMode.mirror,
),
),
width: double.infinity,
height: double.infinity,
child: SafeArea(
child: Column(
children: [
Expanded(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text(
data.albumType.toString(),
style: TextStyle(
fontSize: 30,
color: Colors.white,
fontWeight: FontWeight.bold),
),
Text(
data.id.toString(),
style: TextStyle(
fontSize: 20,
color: Colors.white,
fontWeight: FontWeight.bold),
),
Text(
data.name.toString(),
style: TextStyle(
fontSize: 50,
color: Colors.white,
fontWeight: FontWeight.bold),
),
],
),
),
],
),
),
);
}
} else if (snapshot.connectionState == ConnectionState.waiting) {
return Center(
child: CircularProgressIndicator(),
);
} else {
return Center(
child: Text("${snapshot.connectionState} occured"),
);
}
return Center(
child: Text("Server timed out!"),
);
},
future: _myData!,
),
);
}
enter code here