Mvvmintroduction 130725124207-phpapp01
- 1. Software Architecture Pattern M-V-VM (Model-View-ViewModel) Friday, July 26, 2013
- 4. Model public class Person { public Person() { } public string FirstName { get; set; } public string LastName { get; set; } public string Age { get; set; } }
- 5. ViewModel public class MainViewModel : INotifyPropertyChanged { public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChanged(String propertyName) { PropertyChangedEventHandler handler = PropertyChanged; if (null != handler) { handler(this, new PropertyChangedEventArgs(propertyName)); } } }
- 6. ViewModel private Person _selectedPerson; public Person SelectedPerson { get { return _selectedPerson; } set { if (_selectedPerson != value) { _selectedPerson = value; NotifyPropertyChanged("SelectedPerson"); } } }
- 7. View <TextBox Text="{Binding FirstName, Mode=TwoWay}" />
- 8. View <ListView ItemsSource="{Binding ListOfPerson}" SelectedItem="{Binding SelectedPerson, Mode=TwoWay}" />
- 10. • The Mode property determines how changes are synchronized between the target control and data source – OneTime – Control property is set once to the data value and any subsequent changes are ignored – OneWay – Changes in the data object are synchronized to the control property, but changes in the control are not synchronized back to the data object – TwoWay – Changes in the data object are synchronized to the control property and vice- versa <TextBlock x:Name="FirstName" Text="{Binding FirstName, Mode=OneWay}"/>
- 11. • ViewModels implement INotifyPropertyChanged public class ProfileViewModel : INotifyPropertyChanged { private Person _person; public Person Person { get { return _person; } set { if (value != _person) { _person = value; NotifyPropertyChanged("Person"); } } } public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChanged(String propertyName) { if (null != PropertyChanged) PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } }
- 12. <Button Command="{Binding EditCommand}" CommandParameter="{Binding SelectedPerson}" Content="Edit" HorizontalAlignment="Center" VerticalAlignment="Center"/> class EditPersonCommand : ICommand { ViewModel _viewModel; public EditPersonCommand(ViewModel viewModel) { _viewModel = viewModel; } public event EventHandler CanExecuteChanged; public bool CanExecute(object parameter) { return true; } public void Execute(object person) { _viewModel.EditPerson(person as Person); } }
- 13. • Reuse Model and View-Model code • Test the ViewModel with unit tests • Maintainability • Can show design-time data in Expression Blend and the Visual Studio designer