How to Copy an Object without Create Reference Dart-CodePudding

I want to give object value from another but when I modify name2 it modify name1 at same time.

Item item2 = item1;
item2.name = 'a';

I want every object not linked to each other.

CodePudding user response：

Considering you are using a Map, You can use from to achieve this, reference answer Here

Item Item1 = {
    'foo': 'bar'
};
Item Item2 = new Item.from(Item1);

You can also use fromJson and toJson to achieve this

Item1 = Item.fromJson(Item2.toJson());

but for this you need to create fromJson and toJson manually. you can do that easily by pasting your json here

CodePudding user response：

Let's say you have an item class with the properties id and name. You can copy a class without referencing it if you create a copyWith method like below. It will copy the class and modify only the values that you pass as arguments. Try it out in Dart Pad.

void main() {
  final Item item1 = Item(id: 1, name: 'Item 1');
  final Item item2 = item1.copyWith(name: 'Item 2');
  print(item1); // Item{id: 1, name: Item 1}
  print(item2); // Item{id: 1, name: Item 2}
  print(item1); // Item{id: 1, name: Item 1}
}

class Item {
  const Item({
    required this.id,
    required this.name,
  });
  final int id;
  final String name;

  Item copyWith({int? id, String? name}) => Item(
        id: id ?? this.id,
        name: name ?? this.name,
      );
  
  @override
  String toString()=> 'Item{id: $id, name: $name}';
}