Question 206033 in Flutter Question posted in
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showing an error in my accountModel in flutter

I have created a model class for account of person, where i want to assing transactions to empty array..

i have assigned like this.transactions=[],

here is my modelclass


class AccountModel {
  String id;
  String name;
  DateTime createdOn;
  List<TransactionModel> transactions;
  bool isLocked;
  double payTotal;
  double receiveTotal;
  double balance;
  TransactionModel? lastEntry;


  AccountModel(
      {
required this.id, required this.name,
  this.transactions= [],// this is showing an error


 this.isLocked=false,
        this.balance=0,
        required this.createdOn,
        this.lastEntry,
        this.payTotal=0,
        this.receiveTotal=0,

      });


}
Tags:

2

Answers


  1. 0

    Here is List<TransactionModel> transactions;. Not dynamic type. You assigned with dynamic empty list. Can initialize with TransactionModel object.

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  2. 0

    The error says exactly what’s wrong.

    The default value of an optional parameter must be constant.

    To solve make it a constant by writing const in front of it:

    this.transactions = const []

    EDIT:

    As you have found out, a const list is unmodifiable so it’s not really desired to have. I see two options to solve this. The first is to not make it part of the constructor at all and always initialize it with [] so like

    class AccountModel {
  String id;
  String name;
  DateTime createdOn;
  List<TransactionModel> transactions = [];
  bool isLocked;
  double payTotal;
  double receiveTotal;
  double balance;
  TransactionModel? lastEntry;

  AccountModel({
    required this.id,
    required this.name,
    this.isLocked = false,
    this.balance = 0,
    required this.createdOn,
    this.lastEntry,
    this.payTotal = 0,
    this.receiveTotal = 0,
  });
}

    If you really need it to be part of the constructor maybe this work around works for you:

    class AccountModel {
  String id;
  String name;
  DateTime createdOn;
  List<TransactionModel> _transactions = [];
  List<TransactionModel> get transactions => _transactions;
  set transactions(value) => _transactions = value;
  bool isLocked;
  double payTotal;
  double receiveTotal;
  double balance;
  TransactionModel? lastEntry;

  AccountModel({
    required this.id,
    required this.name,
    List<TransactionModel>? transactions,
    this.isLocked = false,
    this.balance = 0,
    required this.createdOn,
    this.lastEntry,
    this.payTotal = 0,
    this.receiveTotal = 0,
  }) {
    if (transactions != null) _transactions = transactions;
  }
}
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