Make form data preservable

[B3K4682]

Hi 👋

I'm currently working on a feature that involves form filtering using NyFormData, and I ran into a limitation: form state isn't preserved when a user navigates away from the screen and returns back. This causes a poor user experience since users have to re-enter all their filter values from scratch each time.

Here's a simplified version of my form:

class FilterBuildingsForm extends NyFormData {
  FilterBuildingsForm() : super("filter_buildings");

  FormValidator validator = FormValidator.custom((value) {
    num val = double.tryParse(value) ?? -1;
    if (value == null || value.isEmpty) return true;
    return val >= 0;
  }, message: "You can't enter below 0");

  @override
  fields() => [
    Field.number("minPrice", hidden: true, validate: validator),
    Field.number("maxPrice", hidden: true, validate: validator),
    // ... more fields ...
  ];
}

I use this in a screen with NyForm(...), and it's working perfectly for validation and UI binding.

However, when the user navigates back to the screen, the form resets, even though I'd like it to remember the last state until it's manually cleared.

It would be great if NyFormData supported:

• A built-in way to preserve the last entered values, even after navigation.

[agordn52]

Hi @B3K4682,

It would be a nice feature. If I get time I'll explore this more.
I think for now though, you could just use a singleton Controller for your page and then create the Form instance in there.

Your Controller

class ReportController extends Controller {

  ReportAnIssueForm form = ReportAnIssueForm();

  @override
  bool get singleton => true;
} 

NyPage

class ReportAnIssuePage extends NyStatefulWidget<ReportController> {
  static RouteView path = ("/report-an-issue", (_) => ReportAnIssuePage());
  
  ReportAnIssuePage({super.key}) : super(child: () => _ReportAnIssuePageState());
}

class _ReportAnIssuePageState extends NyPage<ReportAnIssuePage> {
  
  @override
  Widget view(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Report An Issue")
      ),
      body: SafeArea(
         child: NyForm(form: widget.controller.form),
      ),
    );
  }
}