实现许多INotifyPropertyChanged

Question

please tell me best way to implement many duplicate INotifyPropertyChanged. I have a MainClass that has 10 children, every child has six field and every field must fired property change when own value changed. this my code but not work:

    public class BaseModel
{

    public string S1 { get; set; }
    public string S2 { get; set; }
    public string S3 { get; set; }
    public string S4 { get; set; }
    public string S5 { get; set; }
    public string S6 { get; set; }
}

and I use a class named ViewModelBase to implement INotifyPropertyChanged. in second step use a class to implement duplicate INotifyPropertyChanged:

    public class ImplementBaseModel : ViewModelBase
{
    private readonly BaseModel _baseModel;
    public ImplementBaseModel()
    {
        _baseModel = new BaseModel();
    }

    public string S1
    {
        get { return _baseModel.S1; }
        set
        {
            if (_baseModel.S1 == value)
                return;

            _baseModel.S1 = value;
            base.OnPropertyChanged("S1");
        }
    }
    public string S2
    {
        get { return _baseModel.S2; }
        set
        {
            if (_baseModel.S2 == value)
                return;
            _baseModel.S1 = value;
            base.OnPropertyChanged("S2");
        }
    }
    // other code...

}

then a model has 10 of this class:

    public class MidClass
{
    public ImplementBaseModel ImplementBaseModel1 { get; set; }
    public ImplementBaseModel ImplementBaseModel2 { get; set; }
   // other field
    public ImplementBaseModel ImplementBaseModel10 { get; set; }

    public MidClass()
    {
        ImplementBaseModel1 = new ImplementBaseModel();
        ImplementBaseModel2 = new ImplementBaseModel();
        // ....
        ImplementBaseModel10 = new ImplementBaseModel();

    }
}

OK finish code! now please tell me why some property not fired when value change? is a best way to implement this code?

Answer 1

In your setters, you never actually set the value. Use:

public string S1
{
    get { return _baseModel.S1; }
    set
    {
        if (_baseModel.S1 == value)
            return;
        baseModel.S1 = value;
        OnPropertyChanged("S1");
    }
}

Note that I removed the base from OnPropertyChanged. It isn't normal to invoke the PropertyChanged event in this way.

All NotifyPropertyChanged does is cause every binding to perform a "get" on their bound property. If the backing field is never updated, they will just get the same data.

Answer 2

as a shortcut, you could also create a local method like

bool UpdateAndRaiseIfNecessary( ref string baseValue, string newValue, [CallerMemberName] string propertyName = null)
{
    if (baseValue != newValue)
    {
        baseValue = newValue;
        OnPropertyChanged( propertyName );
        return true;
    }

    return false;
}

and then all of the setters would be like this:

set
{
    this.UpdateAndRaiseIfNecessary( ref _baseModel.S1, value );
}