[FeatureRequest] Add the reactive validations to the validation rules plugin

[DamienDoumer]

Using reactive UI, we could make the validation process of the validation rules plugin automatic, and even do validation based on other properties of the same ViewModel.

Features

• Add a reactive validation rule mechanism based on the original validation rules plugin
• Make a demo of how these reactive validation rules function on Xamarin.Forms and MAUI

[luismts]

Hi @DamienDoumer,

Thanks for taking your time for this. I will check it out and test it this weekend and let you know.

[DamienDoumer]

Hello, @luismts did you finally check my PR? don't hesitate to let me know if you have any questions regarding my PR.

[luismts]

sorry, I forgot that.

[DamienDoumer]

Ok,

[luismts]

Can you explain a little more about the benefits of your PR?

As far as it goes ReactiveUI has its own validations and adding that workload just for a small profit is not entirely clear to me.

cc @DamienDoumer

[DamienDoumer]

Hi @luismts
ReactiveUI has a validation mechanism, but it is not as flexible as what Validation Rules brings "In my Opinion". I've been using the Validation Rules approach to validating input since 2017, and in my projects, I combine it with reactive UI to validate automatically without having to raise validation when the property's value changes and I find it very handy. I ported my code to your library cause I thought some other people might find value in it.