Dart check if many variable is null

Question

Hello im new in dart language, is someone can help me to write this condition better, it works but it's a lot repetitive and i feel theres a better ways to write it :

 if (var1 != null || var2 != null || var3 != null || var4 != null || var5 != null){ ShowMyWidget }

thank you.

looks fine to me but if you had more variables you could push them into a Map and then create a map that loops through the Map to check if null for each object in the map — mister_cool_beans, Dec 28 '21 at 19:49

score 2 · Answer 1 · answered Jan 30 '23 at 15:33

2

if (![var1, var2, var3, var4, var5].contains(null)){ ShowMyWidget }

answered Jan 30 '23 at 15:33

zgorawski

2,597
4
30
43

It hadn't occurred to me before. Thanks, now my codes will be more organized. – Berke Uğur Mar 01 '23 at 21:47

score 0 · Answer 2 · answered Dec 28 '21 at 19:53

Rather than checking all those variables, I'd make them optional parameters to the widget. If you do that, you can just check if they're null using null-safety inside it, whenever you actually need them.

class TestWidget extends StatelessWidget {
  final String? testPar1;
  final String? testPar2;
  final String? testPar3;
  final String? testPar4;
  const TestWidget({
    this.testPar1,
    this.testPar2,
    this.testPar3,
    this.testPar4,
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text(testPar1 ?? 'nope'),
        Text(testPar2 ?? 'nope'),
        Text(testPar3 ?? 'nope'),
        Text(testPar4 ?? 'nope'),
      ],
    );
  }
}

Keep in mind that your way of doing it isn't wrong.

score 0 · Answer 3 · answered Dec 28 '21 at 20:52

0

If you really want, you could do:

if ([var1, var2, var3, var4, var5].any((x) => x != null)) {
  ShowMyWidget();
}

answered Dec 28 '21 at 20:52

jamesdlin

81,374
13
159
204

score 0 · Answer 4 · answered Dec 29 '21 at 20:29

0

ok thanks you your answers, I'll explain my goal a litle bit more : I have a detail page in may app with many custom widget and i want to check if the variables inside my widgets are null in order to either show or hide it.

My app screenshot

So here for exemple I wanna check if one of the booking link isn't null to display the title.

if (link1 != null || link2 != null || link3 != null || link4 != null || var5 != null){ ShowMyTitle }

answered Dec 29 '21 at 20:29

Pierre Huret

21
2

As it’s currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers [in the help center](/help/how-to-answer). – Community Dec 30 '21 at 00:44

Dart check if many variable is null

4 Answers4