freezedのさまざまな書き方

通常のエンティティを作成する

import 'package:freezed_annotation/freezed_annotation.dart';

part 'user.freezed.dart';
@freezed
class User with _$User {
  factory User({
    required String firstName,
    required String lastName,
    required int age,
    @Default(false) bool isMarried,// If you want to define defaultCalue
  }) = _User;

    const User._(); // if you want to define some function, you must determine private constructor
    bool get fullName => '$firstName $lastName'
  
}

jsonを扱うエンティティを作成する

import 'package:freezed_annotation/freezed_annotation.dart';

part 'user.freezed.dart';
part 'user.g.dart';

@freezed
class User with _$User {
  factory User({
    required String firstName,
    required String lastName,
    required int age,
  }) = _User;

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

Unionクラスを作成する

import 'package:freezed_annotation/freezed_annotation.dart';

part 'user.freezed.dart';
@freezed
class Platform with _$Platform {
  const factory User.woman() = _Woman;
  const factory User.man() = _Man;
  const User._();// Prevent constructing from constructor.
  String get preName => when(man : () => 'Mr.', woman : () => 'Ms.')
}