Issue
Sorry if my question is stupid, but I am studying it by myself and don’t have much experience. 🙂 thanks for your help!
I wanted to change a map to JSON.
I tried to follow https://docs.flutter.dev/development/data-and-backend/json#creating-model-classes-the-json_serializable-way this example, but it is not working as I expected.
assume that the class I am using is
class User {
String? name;
}
User({name});
and I have a json as String userJson = {"name":"Dart"}
I tried to decode the json to a Map and change that to User instance.
When I do print(userJson["name"]) it prints "Dart", but then if I put that into the user class
User user = User(name: value);
print(user.name);
it prints null.
Why is the value not saved into user?
When I pass the value as
User.fromJson(Map<String, dynamic> json) {
name = json["name"];
}
User user = User.fromJson(map);
print(user.name);
then of course it works well.
as I said before,
why can’t I pass the "name" value to the User parameter?
Solution
Use this.name in the constructor instead.
Like so:
class User {
String? name;
User({this.name});
}
Without this., the name from the constructor, is different from the name in the class.
Answered By – Josteve
Answer Checked By – Terry (FlutterFixes Volunteer)