Parsing complex json flutter - json

Question

I am trying to parse a complex json file into my application
I am getting an error Exception: type 'String' is not a subtype of type 'int' in type cast. I don't understand where this is happening and how to fix it
Code
import 'dart:async';
import 'dart:convert';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
Future<List<Character>> fetchCharacters(http.Client client) async {
final response =
await client.get('http://swapi.dev/api/people/');
// Use the compute function to run parsePhotos in a separate isolate.
return compute(parseCharacter, response.body);
}
// A function that converts a response body into a List<Photo>.
List<Character> parseCharacter(String responseBody) {
final parsed = jsonDecode(responseBody).cast<Map<String, dynamic>>();
return parsed.map<Character>((json) => Character.fromJson(json)).toList();
}
class Character {
final String name;
final int height;
final int mass;
final String hairColor;
final String skinColor;
Character({this.name, this.height, this.mass, this.hairColor, this.skinColor});
factory Character.fromJson(Map<String, dynamic> json) {
return Character(
name: json['name'] as String,
height: json['height'] as int,
mass: json['mass'] as int,
hairColor: json['hair_color'] as String,
skinColor: json['skin_color'] as String,
);
}
}
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
final appTitle = 'Isolate Demo';
return MaterialApp(
title: appTitle,
home: MyHomePage(title: appTitle),
);
}
}
class MyHomePage extends StatelessWidget {
final String title;
MyHomePage({Key key, this.title}) : super(key: key);
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(title),
),
body: FutureBuilder<List<Character>>(
future: fetchCharacters(http.Client()),
builder: (context, snapshot) {
if (snapshot.hasError) print(snapshot.error);
return snapshot.hasData
? PhotosList(character: snapshot.data)
: Center(child: CircularProgressIndicator());
},
),
);
}
}
class PhotosList extends StatelessWidget {
final List<Character> character;
PhotosList({Key key, this.character}) : super(key: key);
#override
Widget build(BuildContext context) {
return ListView.builder(
itemCount: character.length,
itemBuilder: (context, index) {
return Card(
elevation: 5,
margin: EdgeInsets.symmetric(vertical: 5, horizontal: 10),
child: Container(
padding: EdgeInsets.all(15),
child: ListTile(
title: Text(
character[index].name,
style: TextStyle(fontSize: 18, color: Colors.black),
),
onTap: () {},
),
),
);
},
);
}
}
json file
"count": 82,
"next": "http://swapi.dev/api/people/?page=2",
"previous": null,
"results": [
{
"name": "Luke Skywalker",
"height": "172",
"mass": "77",
"hair_color": "blond",
"skin_color": "fair",
"eye_color": "blue",
"birth_year": "19BBY",
"gender": "male",
"homeworld": "http://swapi.dev/api/planets/1/",
"films": [
"http://swapi.dev/api/films/1/",
"http://swapi.dev/api/films/2/",
"http://swapi.dev/api/films/3/",
"http://swapi.dev/api/films/6/"
],
"species": [],
"vehicles": [
"http://swapi.dev/api/vehicles/14/",
"http://swapi.dev/api/vehicles/30/"
],
"starships": [
"http://swapi.dev/api/starships/12/",
"http://swapi.dev/api/starships/22/"
],
"created": "2014-12-09T13:50:51.644000Z",
"edited": "2014-12-20T21:17:56.891000Z",
"url": "http://swapi.dev/api/people/1/"
}
]
} ```

Answer 1

just remove as int that you added In your Constructor and use parseInt( json['mass'] ) and parseInt( json['height'] )
parseInt() is a function in dart to convert number string in type int to integer number can use in calculations and like that
check this also : https://dev.to/wangonya/how-you-turn-a-string-into-a-number-or-vice-versa-with-dart-392h