MVVM Light - events on object of model

Question

I have question how to raise events in viemodel on instance of model object ?

If I declare the variables directly in viemodel it is easy. just :

private bool _something;
        public bool something
        {
            get
            {
                return _something;
            }
            set
            {
                _something = value;
                //do something
                RaisePropertyChanged("something");
            }
        } 

but what if in viemodel I have :

private MyModelClass _projekcik;
        public MyModelClass Projekcik
        {
            get
            {
                return _projekcik;
            }
            set
            {
                _projekcik = value;
                RaisePropertyChanged("Projekcik");
            }
        }

where MyModelClass is definied in separate file as :

 public class MyModelClass
    {
       int abc {get;set;}
       int other {get;set;}
    }

and I want raise an event (execute some part of code from viemodel ) when I change value of Projekcik.abc ?

For example Projekcik.abc and Projekcik.other are variables stored selectedvalues from two comboboxes. And I want raise event to refresh/reload items of second combbbox when user change selected object in first combbbox (when Projekcik.abc are changed)

Answer 1

Your best bet is to implement INotifyPropertyChanged in the MyModelClass, and then subscribe to PropertyChanged event to do your logic. E.g.:

private MyModelClass _Projekcik;
public MyModelClass Projekcik
{
    get => _Projekcik;
    set
    {
        if(Equals(value, _Projekcik)) return;
        if(_Projekcik != null)
            _Projekcik.PropertyChanged -= HandlePropertyChanged;
        _Projekcik = value;
        if(_Projekcik != null)
            _Projekcik.PropertyChanged += HandlePropertyChanged;

        void HandlePropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            if (e.PropertyName == "abc")
            {
                //Do your stuff here
            }
        }
    }
}

I assume you know how to properly implement INotifyPropertyChanged.