Parsing Iterative JSON from Firebase to Flutter - json

Question

I have data saved into Realtime Firebase as an iterative JSON as shown in the picture.
Realtime Firebase data
[
{
"name": "Math",
"subMenu": [
{
"name": "Math1",
"subMenu": [
{
"name": "Math 1.1"
},
{
"name": "Math 1.2",
"subMenu": [
{
"name": "Math 1.2.1",
"subMenu": [
{
"name": "Math 1.2.1.1"
},
{
"name": "Math 1.2.1.2"
}
]
},
{
"name": "Math 1.2.2"
}
]
}
]
},
{
"name": "Math2"
},
{
"name": "Math3",
"subMenu": [
{
"name": "Math 1.3.1"
},
{
"name": "Math 1.3.2"
}
]
}
]
},
{
"name": "Marketing",
"subMenu": [
{
"name": "Promotions",
"subMenu": [
{
"name": "Catalog Price Rule"
},
{
"name": "Cart Price Rules"
}
]
},
{
"name": "Communications",
"subMenu": [
{
"name": "Newsletter Subscribers"
}
]
}
]
}
]
How the JSON look like in Realtime Firebase
'Click the image'
datamodel.dart
class Menu {
String? name;
int? font;
List<Menu>? subMenu = [];
Menu({this.name, this.subMenu, this.font});
Menu.fromJson(Map<String, dynamic> json) {
font = json['font'];
name = json['name'];
if (json['subMenu'] != null) {
json['subMenu'].forEach((v) {
subMenu?.add(Menu.fromJson(v));
});
}
}
}
My goal is to build a multilevel list view in Flutter that reflexes iterative JSON structure. So, I implemented a method that returns List<Menu>, and then pass it to a Futurebuilder to build a multilevel list View.
The method.
final ref = FirebaseDatabase.instance.ref();
Future<List<Menu>> firebaseCalls(DatabaseReference ref) async {
final snapshot = await ref.child('Task').get();
final jsondata = snapshot.value as Map<String, dynamic>;
final list = json.decode(jsondata) as List<dynamic>; // Error Location
return list.map((e) => Menu.fromJson(e)).toList();
}
and I got the following
The Error
error: The argument type 'Map<String, dynamic>' can't be assigned to the parameter type 'String'. (argument_type_not_assignable at [flutter_multilevel_list_from_json] lib\main.dart:28)
tried to change the list type to List<dynamic> but still give me an error.

Answer 1

json.decode() takes a String as input, and you are passing a Map<String,dynamic> into it.
That is your problem, not that you are trying to cast it to a List<dynamic>

Answer 2

May be this will be helpful (jsondata as List).map((e) => Menu.fromJson(e)).toList();