Question

OK, so I have a user control which uses values from an underlying business logic class. I need some way for the user control to listen to the class and fire when certain methods are called / values are updated on the BL class.

At a high level, what would be the best way to do this? I know I’d need some form of event in the BL class with a listener in my user control but just wondering the best way to go about it if anyone has any suggestions??

Answer 1

The class that should be listen to has to implement the INotifyPropertyChanged interface and the usercontrol has to subscribe to it. Let me show you a short simple sample. Here is a class that has a property and notifiy changes to it:

public class MyClass : INotifyPropertyChanged
{
    private string myProperty;
    public event PropertyChangedEventHandler PropertyChanged;

    private void RaisePropertyChanged(string propertyName)
    {
        var temp = PropertyChanged;
        if (temp != null)
        {
            temp(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    public string MyProperty
    {
        get { return myProperty; }
        set
        {
            if (myProperty != value)
            {
                myProperty = value;
                RaisePropertyChanged("MyProperty");
            }
        }
    }
}

Your usercontrol should subscribe the PropertyChange event and will be notified on every change.