freezed constructor initialisers

Question

I have model like this (simplified):

@immutable
class CountryModel {
  final String name;
  final String isoCode;
  final String assetPath;

  const CountryModel({
    required this.name,
    required this.isoCode,
  }) : assetPath = 'assets/countries/$isoCode.PNG';
}

now I decided to migrate to freezed but can't understand how to deal with fields like assetPath

I have a lot of models, whose initial values based on constructor parameters

my freezed model:

part 'country_model.freezed.dart';

@freezed
class CountryModel with _$CountryModel {

  const factory CountryModel({
    required String name,
    required String isoCode,
  }) = _CountryModel;
}

// : assetPath = 'assets/countries/$isoCode.PNG'

how to add assetPath field here?

so before migration to freezed if I create CountryModel like this

CountryModel(name: 'name', isoCode: 'XX');

assetPath value should be 'assets/countries/XX.PNG'

How about assign the path or using default value by freezed. — Md. Yeasin Sheikh, Oct 21 '21 at 12:44
it is working here I think, let me share on answer and test it yourself and let me know — Md. Yeasin Sheikh, Oct 21 '21 at 13:10

score 2 · Answer 1 · answered Oct 28 '21 at 14:36

seems like there is no constructor initialisers in freezed
so as an option I solved it in this way:

part 'country_model.freezed.dart';
part 'country_model.g.dart';

@freezed
class CountryModel with _$CountryModel {
  const CountryModel._();

  const factory CountryModel({
    required String name,
    required String isoCode,
  }) = _CountryModel;

  String get assetPath => 'assets/countries/$isoCode.PNG';
}

from my perspective this is not the best solution, I'd prefer to use constructor initialiser but not this time

score 1 · Answer 2 · answered Oct 21 '21 at 13:11

1

I've used Default value for assetPath.

import 'package:freezed_annotation/freezed_annotation.dart';
import 'package:flutter/foundation.dart';

part 'country_model.freezed.dart';
part 'country_model.g.dart';

@freezed
class CountryModel with _$CountryModel {
   factory CountryModel({
    required String name,
    required String isoCode,
    @Default("assets/countries/\$isoCode.PNG") String assetPath,
  }) = _CountryModel;

  factory CountryModel.fromJson(Map<String, dynamic> json) =>
      _$CountryModelFromJson(json);
}

answered Oct 21 '21 at 13:11

Md. Yeasin Sheikh

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ok , and you can find more on [pub](https://pub.dev/packages/freezed) – Md. Yeasin Sheikh Oct 21 '21 at 13:39
unfortunately it doesn't work :/ it produces values like this `assets/countries/$id.png` instead of `assets/countries/US.png` – Nagual Oct 25 '21 at 19:07
If you want to use default `US.png` pass it there, to modify it you can use `.copyWith` – Md. Yeasin Sheikh Oct 25 '21 at 22:42

freezed constructor initialisers

2 Answers2