Flutter how to get specific value from json http response - json

Question

I am using this code to upload json data to my nodejs server.
HttpClient client = new HttpClient();
var data = createSamplePayment().toJson();
var request = await client.openUrl('POST', Uri.parse(serverEndpoint + '/paymentrequests'));
request.headers.set(HttpHeaders.contentTypeHeader, 'APPLICATION/JSON');
request.write(json.encode(data));
var response = await request.close();
String reply = await response.transform(utf8.decoder).join();
print(reply);
The output from print(reply) is:
flutter: {"url":"https://paymentrequests/86C0110D","token":"w8SWavZNjOG","id":"C3C4966AF64D8CE194F5E3C"}
But I only want to get ”token” value. What can I do to fix that? I have tried in many different ways without success.

Answer 1

class DetailsModel {
String url;
String token;
String id;
DetailsModel({this.url, this.token, this.id});
DetailsModel.fromJson(Map<String, dynamic> json) {
url = json['url'];
token = json['token'];
id = json['id'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['url'] = this.url;
data['token'] = this.token;
data['id'] = this.id;
return data;
}
}
Firstly, convert your response into a Model, to do that you would need the above code. Then map your response.
DetailsModel details = DetailsModel.fromJson(response);
Then to access the details you can simply use.
dynamic token = details.token;
print(token); // w8SWavZNjOG

Answer 2

You can copy paste run full code below
I use the following code to simulate this case
You can do payloadFromJson(reply) and return payload.token
You can reference Payload class in full code
code snippet
Payload payloadFromJson(String str) => Payload.fromJson(json.decode(str));
...
Future<String> postWithClientCertificate() async {
...
Payload payload = payloadFromJson(reply);
print(payload.token);
return payload.token;
}
output
I/flutter ( 5995): w8SWavZNjOG
I/flutter ( 5995): token w8SWavZNjOG
full code
import 'dart:convert';
import 'dart:io';
import 'package:flutter/material.dart';
import 'dart:convert';
Payload payloadFromJson(String str) => Payload.fromJson(json.decode(str));
String payloadToJson(Payload data) => json.encode(data.toJson());
class Payload {
Payload({
this.url,
this.token,
this.id,
});
String url;
String token;
String id;
factory Payload.fromJson(Map<String, dynamic> json) => Payload(
url: json["url"],
token: json["token"],
id: json["id"],
);
Map<String, dynamic> toJson() => {
"url": url,
"token": token,
"id": id,
};
}
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() async{
String token = await postWithClientCertificate();
print("token $token");
setState(() {
_counter++;
});
}
Future<String> postWithClientCertificate() async {
/*final serverEndpoint = 'https://1991269db78887f9e.ngrok.io';
HttpClient client = new HttpClient();
var data = createSamplePayment().toJson();
var request = await client.openUrl('POST', Uri.parse(serverEndpoint + '/paymentrequests'));
request.headers.set(HttpHeaders.contentTypeHeader, 'APPLICATION/JSON');
request.write(json.encode(data));
var response = await request.close();
String reply = await response.transform(utf8.decoder).join();
print(reply);*/
String reply =
'''{"url":"https://paymentrequests/86C0110D","token":"w8SWavZNjOG","id":"C3C4966AF64D8CE194F5E3C"}''';
Payload payload = payloadFromJson(reply);
print(payload.token);
return payload.token;
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}