Answer by HongerTrollie for Dart: spread operator for constructor

The spread operator will work on Maps e.g. Map<String, dynamic> so what worked for me was to convert the object to json which is Map<String, dynamic>, use the spread operator and then convert back to the object.

You can try something like this:

class Something {  final String id;  final String name;  Something({required this.id, required this.name});  factory Something.fromJson(Map<String, dynamic?> json){    return Something(      id: json['id'],      name: json['name']    );  }  Map<String, dynamic?> toJson() {    return {'id': id,'name': name    };  }}final x = Something(id: 'abc', name: 'def');final y = Something.fromJson({...x.toJson(), 'name': 'somethingElse'})

This might be very expensive to do, but if all you care about is using the spread operator, this should do the job.