Newbie question regarding validation

I am a beginner in MVVM and I am not sure which is the best approach:

I have some domain-level models, like User, Product, ProductGroup, etc. My ViewModels only have one one property which implements INPC, like this:

public ProductGroupViewModel(ProductGroup productGroup) : Screen
        {
            _productGroup = productGroup;
        }

        private ProductGroup _productGroup;
        public ProductGroup ProductGroup
        {
            get => _productGroup;
            set
            {
                _productGroup = value;
                SetAndNotify(ref _productGroup, value);
            }
        }
}

In the View, all the binding is done like this, and this works: Text="{Binding ProductGroup.Name}"

I also use the same View / ViewModel to create a new ProductGroup and edit an existing one, through the contructor. But in this way, I cannot use Stylet IoC to inject the validator, because my contructing viewmodel does not know how to resolve such a constructor:

public ProductGroupViewModel(ProductGroup productGroup, IModelValidator<ProductGroupViewModel> validator) : base(validator)
        { ... }

What would be the recommended way to solve this issue? Thanks in advance.

[hmihail]

Thanks alot! You have been a great help!

[hmihail]

Thanks for your support!