Propertiey values based on another property

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C#

.NET

LINQ

MVC

Hi,

I have a class A, it has properties P1 string, P2 int, P3 int, P4 double, lstB<'B'>, lstC<'C'>, lstD<'D'> and nested classes B,C and D. Now on property change of P1 I have selected values from lstB and assigned them as sources for my gird's combo box column and selected value is binded to P2, same goes for P3-lstC and P4-lstD, Now for the first time I want to set P2 equal to first value in the source and same for P3 and P4 but doing that gets the system in deadlock and I have to close my browser and re-run the application. Thanks in advance.

Zafar

public class A : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private ObservableCollection<BModel> _BList = new ObservableCollection<BModel>();
    private ObservableCollection<CModel> _CList = new ObservableCollection<CModel>();
    private string _P1;
    private int _P2;
    private int? _P3;
    private double? _P4;

    public string P1
    {
        get { return _P1; }
        set
        {
            _P2 = value;
            OnPropertyChanged("P1");
        }
    }

    public int? P2
    {
        get { return _P2; }
        set
        {
            _P2 = value;
            OnPropertyChanged("P2");
        }
    }

    public int? P3
    {
        get { return _P3; }
        set
        {
            _P3 = value;
            IsDirty = true;
            P4 = (from r in _lstrate where r.VATCodeId == this.VATCodeId && r.VATListId ==    this.VATListId select r.Rate).FirstOrDefault();
            OnPropertyChanged("P3");
        }
    }
    public double? P4
    {
        get { return _P4; }
        set
        {
            _P4 = value;
            OnPropertyChanged("P4");
        }
    }

    public IEnumerable<BModel> AvailableAList
    {
        get
        {
            return from v in _BList where v.P1 == this.P1 select v;
        }
    }

    public IEnumerable<CModel> AvailableBList
    {
        get
        {
            return from c in _CList where c.P2 == this.P2 select c;
        }
    }

    public A(string p1, int p2, int? p3, double? p4,
        ObservableCollection<BModel> bList, ObservableCollection<CModel> cList)
    {
        this._P1 = p1;
        this._P2 = p2;
        this._P3 = p3;
        this._P4 = p4;
        this._BList = bList;
        this._CList = cList;
    }

    public void OnPropertyChanged(string name)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(name));
        }
    }

    public class BModel
    {
        public int P2
        {
            get;
            set;
        }
        public string P2Code
        {
            get;
            set;
        }
        public string P1
        {
            get;
            set;
        }

        public BModel(int p2, string p2code, string p1)
        {
            this.P2 = p2;
            this.P2Code = p2code;
            this.P1 = p1;
        }
    }

    public class CModel
    {
        public int P3
        {
            get;
            set;
        }
        public string P3Code
        {
            get;
            set;
        }
        public int P2
        {
            get;
            set;
        }

        public CModel(int p3, string p3code, int p2)
        {
            this.P3 = p3;
            this.P3Code = p3Code;
            this.P2 = p2;
        }
    }
}

this code is working fine, but if I try to set values of P2 on change of P1 and P3 on change of P2 and P4 on change of P3, then the system does not respond.