Add a source generator to simplify IPopupService interaction.

[Saeras]

With Popup V2, the design of passing data to the view model is much more cumbersome than before. Previously this would be possible by setting the properties in a type safe manner on the view model instance that is already bound to the popup instance, for example:

class MainViewModel : ObservableObject
{
    [RelayCommand]
    public async Task ShowTextAsync()
    {
        await popupService.ShowPopupAsync<PopupViewModel>(vm =>
        {
            vm.Text = "Sample Text";
        });
    }
}

This same workflow is no longer type safe, and requires corresponding mappings on both the popup view model side and the view model that wishes to show the popup. This change was made for what appears to be standardization with the IQueryAttributable interface in the .NET MAUI Framework. Similar topics have been raised on other issues (#1733, #2693, #2696, #3029, etc.). The current workflow at this time now changes the simplicity above to:

class MainViewModel : ObservableObject
{
    [RelayCommand]
    public async Task ShowTextAsync()
    {
        // Displaying the popup.
        var properties = new Dictionary<string, object>
        {
            [nameof(PopupViewModel.Text)] = "Sample Text";
        };
        await popupService.ShowPopupAsync<PopupViewModel>(Shell.Current, null, properties);
    }
}

class PopupViewModel : ObservableObject, IQueryAttributable
{
    [ObservableProperty]
    public string? Text { get; set; }

    // Binding the properties
    void IQueryAttributable.ApplyQueryAttributes(Dictionary<string, object> parameters)
    {
        Text = (string?)parameters[nameof(Text)];
    }
}

With numerous properties, the coordination between the MainViewModel and PopupViewModel quickly becomes a maintenance nightmare, particularly ensuring the types are coordinated between the MainViewModel and PopupViewModel appropriately.

I would like to propose that a source generator be created that helps coordinate the properties. For example, the PopupViewModel could be attributed with a [QueryAttributable] attribute which would generate the ApplyQueryAttributes implementation, and that same attribute could be used to generate some sort of extension method to display the popup using a syntax possibly similar to the original Task<Result> ShowMyPopupAsync<Result>(this IPopupService popupService, Action<PopupViewModel> configure);

[VladislavAntonyuk]

Fix me if I am wrong but it is already available out of the box. The attribute already available and you only set the path as a parameter.