flutter - How to use provider to create a commit/discard changes pattern?

Question

What would be a best practice for (provider based) state management of modal widgets in flutter, where when user makes an edit changes do not propagate to parent page until user confirms/closes modal widget. Optionally, user has a choice to discard the changes.

In a nutshell:

• modal widget with OK and cancel actions, or
• modal widget where changes are applied when modal is closed

Currently, my solution looks like this

1. Create a copy of the current state
2. Call flutter's show___() function and wrap widgets with a provider (using .value constructor) to expose copy of the state
3. If needed, update original state when modal widget is closed

Example of case #2:

Future<void> showEditDialog() async {
  // Create a copy of the current state
  final orgState = context.read<MeState>();
  final tmpState = MeState.from(orgState);

  // show modal widget with new provider
  await showDialog<void>(
    context: context,
    builder: (_) => ChangeNotifierProvider<MeState>.value(
              value: tmpState,
              builder: (context, _) => _buildEditDialogWidgets(context)),
  );

  // update original state (no discard option to keep it simple)
  orgState.update(tmpState);
}

But there are issues with this, like:

• Where should I dispose tmpState?
• ProxyProvider doesn't have .value constructor.
• If temporary state is created in Provider's create: instead, how can I safely access that temporary state when modal is closed?

Answer 1

等待大神答复