Get all Validation Errors in ValidatingModelBase Easily

[uyaem]

It is currently not possible to do validation and get all the errors to display them to the user.

I am using the FluentModelValidator<> implementation from the documentation.
My use case is a popup dialog with several interdependent input fields, where the Save button shall revalidate the form and display a summary of validation errors if there are any.

It is currently not possible to do this using singular method calls:

1. Call this.ValidateAsync() in the ViewModel.
   This uses the underlying INotifyDataErrorInfo interface and causes ValidatingModelBase to collect the errors nicely, but I have no way of just getting all errors. There is IValidationModel.GetErrors(string), but I'd have to know all the property names, loop, ...

2. Call this.Validator.ValidateAllPropertiesAsync() in the ViewModel.
   I get all errors, but since this cannot raise INotifyDataErrorInfo events, the controls of the View (which might want to react by e.g. displaying a decorator) are not notified.

Any workaround is either impossible or has serious code smells:

• Calling both of the above methods. I get error string and decorators, but I'm running all validations twice.
• Subscribing to INotifyDataErrorInfo - cumbersome and duplicate work, since ValidatingModelBase already does all that work.
• Using IModelValidator<T>.ValidateAllPropertiesAsync. in my ViewModel, then propagating the result myself via ViewModelBase.RecordPropertyError(...) - dupliate work, but the least added boilerplate code

Ideally, I would love to have an extension method ValidatingModelBase.ValidateAllPropertiesAsync() which raises INotifyDataErrorInfo events and returns the errors like the IModelValidator<T>.ValidateAllPropertiesAsync()., so I get the combination of 1. and 2. above.
Sadly, I cannot implement it as extension method because ValidatingModelBase.Validator has a protected getter.