class CreditModel { final int? credit; final int? freeCredit; final int? giftCredit; CreditModel({this.credit, this.freeCredit, this.giftCredit}); CreditModel copyWith({ int? credit, int? freeCredit, int? giftCredit, }) { return CreditModel( credit: credit ?? this.credit, freeCredit: freeCredit ?? this.freeCredit, giftCredit: giftCredit ?? this.giftCredit, ); } }