响应后代类PropertyChanged事件

Question

I have a class, BaseSample, that uses another class, MainData, as one of its fields:

Protected _sampleData As MainData

Public Property SampleData() As MainData

    Get

        Return _sampleData

    End Get

    Set(ByVal value As MainData)

        _sampleData = value

    End Set


End Property

MainData in turn has a collection of a class, ProcessData, as a field and ProcessData has a collection of a class, Measurement, as a field. Ie:

MainData

 |- IEnumerable (Of ProcessData) |- IEnumerable (Of Measurement) 

These classes are entities in a LINQ to SQL file. In the Measurement class, I raise the PropertyChanged event when the CrucibleOxidizedMass property changes:

Private Sub OnCrucibleOxidizedMassChanged()

    RaiseEvent PropertyChanged(Me, New ComponentModel.PropertyChangedEventArgs("CrucibleOxidizedMass"))

End Sub

In the BaseSample class, I want to respond to the CrucibleOxidizedMass PropertyChanged event in any of the descendent Measurment instances. How would I do this?

Answer 1

Iterate through all ProcessDates and for each one iterate through each Measurement and subscribe to the event.

In C# code:

foreach(var processData in value.ProcessDatas)
{
    foreach(var measurement in processData.Measurements)
    {
        measurement.PropertyChanged += OnMeasurementPropertyChanged;
    }
}

Be sure to unsubscribe from those events, when new sample data is set. Also, you probably should unsubscribe from individual events when either a measurement is removed from a ProcessData or when a ProcessData is removed from the SampleData .