Property only set after change of focus at binded input

In my xaml I have a textbox which is binded to a property in my viewmodel: XAML: ``` <TextBox HorizontalAlignment="Left" Height="30" Margin="10,10,0,0" TextWrapping="Wrap" Text="{Binding City}" VerticalAlignment="Top" Width="191" Grid.Column="1" Grid.Row="6"/> ``` View model: ``` public class MyViewModel : INotifyPropertyChanged { ... public string City { get { return _model.Address.City; } set { if (_model.Address.City != value) { _model.Address.City = value; RaisePropertyChanged("City"); } } } ... } ``` Two-way-data-binding works well but it seems that a properties value is only set when the focus is changed from the city input to another object. I would like to save my context when a hotkey (ENTER) is pressed. When I now enter a city and press ENTER afterwards, the property doesn't contain the new value. When I enter a city, change the focus to another object and press ENTER, the property contains the right value. How to solve this problem?