Use object setters dynamically with dart - flutter

Question

Objective
Create a method that sets value to the object created above.
This method could be used like below.
setValueToUser(userPropertyName, value);
Given
A mutable model made with freezed.
import 'package:freezed_annotation/freezed_annotation.dart';
part 'user.freezed.dart';
part 'user.g.dart';
#unfreezed
class User with _$User {
factory User({
required int id,
required String email,
required String password,
required DateTime birthday,
}) = _User;
factory User.fromJson(Map<String, dynamic> json) =>
_$UserFromJson(json);
}
What I tried
switch-case statement
First, I made something like this, but this ends up being very tedious as an actual user model has 109 property members :(
User setValueToUser(String propertyName, dynamic value){
final user = User();
switch (propertyName) {
case 'id':
user.id = value as int;
break
case 'email':
user.email = value as String;
break
case 'password':
user.password = value as String;
break
case 'birthday':
user.birthday = value as DateTime;
break
}
return user;
}
Map
Then, I created a map, but dart requires all fields of a map to be initialized when the map variable initializes, so failed achieve the goal.
User setValueToUser(String propertyName, dynamic value) {
final user = User();
final userDictionary = <String, dynamic>{
'id': user.id = value as int,
'email': user.email = value as String,
'password': user.password = value as String,
'birthday': user.birthday = value as DateTime,
};
userDictionary[propertyName]; // I intend to set value to ONLY one specific property at a time. Apparently, this line means nothing to dart :(
return user;
}
Conclusion
I know setting a property name with string looks very ridiculous. I do want to avoid using string if possible, so comments and answers regarding this is very much welcomed. (But setting enum for all properties of the class would be tedious, I think)