File structure needs to be refactored.
The view model should extend the System.ComponentModel.INotifyPropertyChanged interface for the ui binding to know when an update occurs.
public class NewPersonWindowViewModel : INotifyPropertyChanged
{
}
Conform to the interface by adding the event PropertyChangedEventHandler property.
public event PropertyChangedEventHandler PropertyChanged;
For convenience, declare NotifyPropertyChanged to fire the PropertyChanged event.
public void NotifyPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
Declare the private fields and their corresponding public properties that will be bound to in the UI. Notice the call to the NotifyPropertyChanged method in the SelectedPerson object's setter. This call notifies the UI when to make a change once the binding is configured. It is important to note that if a list is needed, use the System.Collections.ObjectModel.ObservableCollection<T> instead of a list, array, or other collection to ensure the UI elements are updated when calling Add, Remove, etc.
string fullName;
public string FullName
{
get
{
return fullName;
}
set
{
fullName = value;
NotifyPropertyChanged("FullName");
}
}
In the view controller's constructor, simply instantiate the view model and assign it to the DataContext property. Note: The DataContext property can be set in the view xaml. I chose to do it here instead
viewModel = new NewPersonWindowViewModel();
DataContext = viewModel;
The Last step is to add the binding on the ui element. Set the UpdateSourceTrigger property to PropertyChanged to update the bound property on change.
<TextBox x:Name="nameTextBox" TextWrapping="Wrap" FontSize="16" Text="{Binding FullName, UpdateSourceTrigger=PropertyChanged}"/>