Parse nested json tree using flutter - flutter

Question

I have a json nested tree that looks like this :
{
"children": [
{
"children": [],
"id": 9,
"level": 1,
"name": "Zone d'audit Interne"
},
{
"children": [],
"id": 10,
"level": 1,
"name": "Magasin PF"
},
{
"children": [],
"id": 11,
"level": 1,
"name": "Magasin MP"
},
{
"children": [
{
"children": [],
"id": 14,
"level": 2,
"name": "Packaging"
},
{
"children": [],
"id": 15,
"level": 2,
"name": "Labelling"
},
{
"children": [],
"id": 16,
"level": 2,
"name": "Assemblage Acc"
}
],
"id": 12,
"level": 1,
"name": " U4: Assembalge Finale"
},
{
"children": [
{
"children": [],
"id": 18,
"level": 2,
"name": "Contrôle traitement"
},
{
"children": [],
"id": 19,
"level": 2,
"name": "Tunnel de Séchage"
},
{
"children": [],
"id": 20,
"level": 2,
"name": "Traitement Mécanique"
}
],
"id": 17,
"level": 1,
"name": "U3: Traitement"
},
{
"children": [
{
"children": [],
"id": 23,
"level": 2,
"name": "Ass_Ligne 2"
},
{
"children": [],
"id": 24,
"level": 2,
"name": "Ass_ligne 1"
},
{
"children": [],
"id": 39,
"level": 2,
"name": "BU"
}
],
"id": 21,
"level": 1,
"name": "U2: Assemblage SF"
},
{
"children": [
{
"children": [],
"id": 26,
"level": 2,
"name": "Mgasin Tampon"
},
{
"children": [],
"id": 27,
"level": 2,
"name": "Contrôle Kitting"
}
],
"id": 25,
"level": 1,
"name": "U1: Kitting"
},
{
"children": [],
"id": 35,
"level": 1,
"name": "to-delete"
}
],
"id": 8,
"level": 0,
"name": "DEMO"
}
I've tried parsing it but I only figured out how to parse the first level.
I want to be able to parse it and print / use every node's level .
if possible I want to turn it into a list of objects so I can use it in my widgets,
If anyone can help I'd be grateful
here's how am parsing it :
Future<Map<String, dynamic>?> fetchPerimeterTree(
{required int id, required String baseUrl}) async {
try {
final request = http.Request(
'GET', Uri.parse("$baseUrl${Endpoints.fetchPerim}$id/json"));
http.StreamedResponse response = await request.send();
if (response.statusCode == 200) {
debugPrint("Perimeters tree fetched with success");
var jsonData = jsonDecode(await response.stream.bytesToString());
List<dynamic> fetchData2 = jsonData["children"];
fetchData2.forEach((element) {
print(element["name"]);
print(element["children"]);
print(element["level"]);
});
print(fetchData2);
return jsonData;
} else {
throw Exception('Failed to load perimeter tree ${response.statusCode}');
}
} catch (ex) {
debugPrint(ex.toString());
}
}

Answer 1

Assumed your json called jsonData, and define a class model like this:
class ChildModel {
final int id;
final int level;
final String name;
final List<ChildModel>? children;
ChildModel(
{required this.id,
required this.level,
required this.name,
this.children});
static ChildModel fromJson(Map<String, dynamic> json) {
List children = json["children"] as List;
return ChildModel(
id: json["id"],
level: json["level"],
name: json["name"],
children: children.isNotEmpty
? children.map((e) => ChildModel.fromJson(e)).toList()
: []);
}
}
then you can get your data like this:
ChildModel result = ChildModel.fromJson(jsonData);
and you can test it like this:
print(" name = ${result.children?[3].children?[0].name}"); // name = Packaging
In this way you can cache all the layers of children.