JsonKey to serialize object of object

[nisa10880]

Is it possible to use jsonkey to generate a line like this firstName: json ['customKey']['firstName'] as String,

Let's say I have an object like this from the server.

{
  customKey :  { firstName: ' MyFirstName'
                         lastName: 'MyLastName' 
                        },
 dateOfBirth: '1997-12-17T03:24:00' 
}

And I want to create a Flutter Class like this

@JsonSerializable(nullable: false)
class Person {
  final String firstName;
  final String lastName;
  final DateTime dateOfBirth;
  Person({this.firstName, this.lastName, this.dateOfBirth});
  factory Person.fromJson(Map<String, dynamic> json) => _$PersonFromJson(json);
  Map<String, dynamic> toJson() => _$PersonToJson(this);
}

Person _$PersonFromJson(Map<String, dynamic> json) {
  return Person(
    **firstName: json['customKey']['firstName'] as String,**
    **lastName: json['customKey']['lastName'] as String,**
    dateOfBirth: DateTime.parse(json['dateOfBirth'] as String),
  );
}

Map<String, dynamic> _$PersonToJson(Person instance) => <String, dynamic>{
      'firstName': instance.firstName,
      'lastName': instance.lastName,
      'dateOfBirth': instance.dateOfBirth.toIso8601String(),
    };

[kevmoo]

Duplicate of #490