Display JSON data in Flutter - node.js

Question

I want to display some data I am receiving from an API, this is the data I am receiving from my Node JS server:
[
{
"NAME": "Matematicas"
},
{
"NAME": "Naturales"
},
{
"NAME": "Ciencias Sociales"
},
{
"NAME": "Lenguaje"
},
{
"NAME": "Religion"
}
]
This is how I am receiving the data in my front end (UPDATED WITH #Mofidul Islam):
Future<List<Subject>> fetchSubject() async {
var url = Uri.http('localhost:8000', "/subjects");
var prefs = await SharedPreferences.getInstance();
var token = prefs.getString('token');
final response = await http.get(
Uri.parse('http://localhost:8000/subjects'),
headers: {'x-access-token': token!});
print(response.body);
List<dynamic> list = "[" + response.body + "]" as List<dynamic>;
List<Subject> subjectList = [];
list.forEach((element) {
subjectList.add(Subject.fromJson(element));
});
return subjectList;
}
This is the class to handle the incoming data (UPDATED WITH #Mofidul Islam):
class Subject {
final String name;
Subject({
required this.name,
});
factory Subject.fromJson(Map<String, dynamic> json) {
return Subject(name: json['NAME'] as String);
}
parseJson(String responseBody) {
final parsed = jsonDecode(responseBody).cast<Map<String, dynamic>>();
return parsed.map<Subject>((json) => Subject.fromJson(json)).toList();
}
}
This is my init state:
void initState() {
super.initState();
futureSubject = fetchSubject();
}
This is how I am trying to display the data:
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Materias',
theme: ThemeData(
primarySwatch: Colors.green,
),
home: Scaffold(
appBar: AppBar(
title: const Text('Materias'),
),
body: Center(
child: FutureBuilder<List<Subject>>(
future: futureSubject,
builder: (context, snapshot) {
if (snapshot.hasData) {
return Column(
children: snapshot.data!
.map((subject) => Text(subject.name))
.toList(),
);
} else if (snapshot.hasError) {
return Text('${snapshot.error}');
}
return const CircularProgressIndicator();
},
),
),
),
);
}
However, the only thing being displayed when the page loads is:
Matematicas
I am trying to achieve 2 things:
Display the data in a list fashion like:
Subject Name
Matematicas
Naturales
Ciencias Sociales
Lenguaje Religion
Be able to use them as a link to another page when clicked
PD: If I remove the index access [0] on return Subject.fromJson(jsonDecode(response.body)[0]);
I get Expected a value of type Map<String, dynamic> but got one of type List<dynamic>
Any recommendations or guide on how to go through this?
Thank you for your time

Answer 1

You need to loop it
parseJson(String responseBody) {
final parsed = jsonDecode(responseBody).cast<Map<String, dynamic>>();
return parsed
.map<Subject>((json) => Subject.fromJson(json))
.toList();
}
and change your api call to this
Future<List<Subject>> fetchSubject() async {
.....
return parseJson(json.encode(response.body));
}
sorry for my english.

Answer 2

Please try this one and return List from api method
Future<List<Subject>> fetchSubject() async {
var url = Uri.http('localhost:8000', "/subjects");
var prefs = await SharedPreferences.getInstance();
var token = prefs.getString('token');
final response = await http.get(Uri.parse('http://localhost:8000/subjects'),
headers: {'x-access-token': token!});
List<dynamic>list=response.body as List<dynamic>;
List<Subject>subjectList=[];
list.forEach((element){
subjectList.add(Subject.fromJson(element));
});
return subjectList;
}
refactor UI like this
Center(
child: FutureBuilder<List<Subject>>(
future: futureSubject,
builder: (context, snapshot) {
if (snapshot.hasData) {
return Column(children: snapshot.data.map((subject)=>Text(subject.name)).toList(),);
} else if (snapshot.hasError) {
return Text('${snapshot.error}');
}
return const CircularProgressIndicator();
},
),
)