From json method in subclasses - json

Question

I have a base class like:
class TransportationVehicle {
String name;
TransportationVehicle(this.name);
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = <String, dynamic>{};
data['name'] = name;
return data;
}
}
And multiple sub-classes like:
class Bike extends TransportationVehicle {
int pedals;
Bike(String name, this.pedals) : super(name);
#override
Map<String, dynamic> toJson() {
final data = super.toJson();
data['pedals'] = pedals;
return data;
}
}
With that, I can transform a list of different types into a json string. But how would that work with fromJson functionality?

Answer 1

You can use the same idea from the toJson() method by using the base class.
import 'dart:convert';
class TransportationVehicle {
final String? name;
TransportationVehicle({
this.name,
});
factory TransportationVehicle.fromRawJson(String str) =>
TransportationVehicle.fromJson(json.decode(str));
String toRawJson() => json.encode(toJson());
factory TransportationVehicle.fromJson(dynamic json) => TransportationVehicle(
name: json['name'] == null ? null : json['name'] as String,
);
Map<String, dynamic> toJson() => {
'name': name == null ? null : name,
};
}
class Bike extends TransportationVehicle {
final int? pedals;
Bike({
String? name,
this.pedals,
}) : super(name: name);
factory Bike.fromRawJson(String str) => Bike.fromJson(json.decode(str));
String toRawJson() => json.encode(toJson());
factory Bike.fromJson(dynamic json) {
TransportationVehicle vehicle = TransportationVehicle.fromJson(json);
return Bike(
name: vehicle.name == null ? null : vehicle.name,
pedals: json['pedals'] == null ? null : json['pedals'] as int,
);
}
Map<String, dynamic> toJson() {
final data = super.toJson();
data['pedals'] = pedals == null ? null : pedals;
return data;
}
}