OnPropertyChanged

OnPropertyChanged is a convention used in .NET to raise PropertyChanged events to notify data-binding clients that a property value has changed. It is part of the INotifyPropertyChanged interface in System.ComponentModel and is essential in MVVM and similar patterns in WPF, UWP, Xamarin.Forms, MAUI, and Blazor.

The interface defines an event: event PropertyChangedEventHandler PropertyChanged; A common helper method named OnPropertyChanged triggers the event: OnPropertyChanged(string propertyName) { PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName)); }

Modern code often uses CallerMemberName to avoid specifying names: protected void OnPropertyChanged([CallerMemberName] string propertyName = null) { PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName)); } with using System.Runtime.CompilerServices;. Then usage: OnPropertyChanged() inside a property's setter after the value changes.

Example of a typical property with change notification:

private string _name;

public string Name

{

get => _name;

set

{

if (_name != value)

{

_name = value;

OnPropertyChanged();

}

}

}

Notes and best practices include that OnPropertyChanged should be called after updating the backing field, and only when the value actually changes. Some frameworks provide helper methods, such as SetProperty, to reduce boilerplate. If updates occur on background threads, changes bound to the UI should be marshaled to the UI thread, as the PropertyChanged event itself does not enforce threading. The pattern remains widely used with INotifyPropertyChanged across leading .NET UI frameworks.