MugenMvvmToolkit - cross-platform MVVM framework

Introduction

• Winforms
• WPF
• Silverlight 5
• Silverlight for WP7.1, WP8, WP8.1
• Xamarin.Android
• Xamarin.iOS
• Xamarin.Forms
• WinRT XAML framework for Windows 8 Store apps

Data binding

• Lack of extensibility. Perhaps the most important drawback that causes everyone else. Perhaps Microsoft was in a hurry to implement Binding, as all infrastructure classes have an internal access modifier, and if the class is public, then all of its virtual methods are marked with an internal modifier. The situation illustrates well the comments on the public class.System.Windows.Expression:
  

  //“This type supports the Windows Presentation Foundation (WPF) infrastructure and is not intended to be used directly from your code”.

• Redundant syntax. For example, you have declared a property of type bool and you want to use its negation in Binding. To do this, you need to write a converter class to invert the value, register it in resources, and only then it will be available in the code. Binding in this case looks something like this:
  {Binding HasErrors, Converter={StaticResource InverseBooleanConverter}}
  It would be quite logical and natural to use the familiar “!” Operator:
  {Binding !HasErrors}
  
• Lack of Binding support for control events. Probably, many used some kind of helper class EventToCommandfor these purposes.
• Platform dependent. Binding capabilities are highly platform specific. For example, on Windows Phone there is no way to update Binding to change the property ( UpdateSourceTrigger=PropertyChanged). On the WinRT platform, this feature returned, but the properties ValidatesOnExceptionsand those ValidatesOnNotifyDataErrorsresponsible for validation disappeared, and the property StringFormatresponsible for formatting the result also disappeared .

• Extensibility. When creating a Binding, the parser builds a syntax tree, and this allows you to easily expand it without manipulating the text. The structure is very similar to expression trees in C #.
• C # syntax support. Binding supports all major operators ( ??, ?:, +, -, *, /, %, , ==, !=, <, >, <=, >=, &&(and), ||(or), |, &, !, ~), the priority of operations is taken into account in accordance with the C # language standard. Supported lambda expressions, the derivation of generic types based on values, method calls, extension method calls, Linq.
  Syntax Example:
  TargetPath SourcePath, Mode=TwoWay, Validate=true
  
  • TargetPath - the way for Binding from control.
  • SourcePath - the path for Binding from a data source or an expression in C #, you can use several paths.
  • Mode, Validate- additional parameters for Binding, for example Mode, Fallback, Delay, etc.
  
  Keywords:
  
  • $self- returns the current control to which Binding is installed, an analog {RelativeSource Self}.
  • $root - returns the current root element for the control on which Binding is installed.
  • $context- returns the current DataContextfor Binding, analog {RelativeSource Self, Path=DataContext}.
  • $args- returns the current parameter EventArgs, can be used only if it TargetPathindicates an event.
  
  
  Examples

  Text Property, Mode=TwoWay, Validate=True
  Text Items.First(x => x == Name).Value + Values.Select(x => x.Value).First(x => x == Name), Fallback=’empty’
  Text $string.Format('{0} {1}', Prop1, Prop2), Delay=100
  Text $string.Join($Environment.NewLine, $GetErrors()), TargetDelay=1000
  Text Property.MyCustomMethod()
  Text Prop1 ?? Prop2
  Text $CustomMethod(Prop1, Prop2, ‘string value’)
  Text Prop1 == ‘test’ ? Prop2 : ‘value’
  

  
  
  
  
• Binding support for control events with access to the parameter EventArgsusing the keyword $args.
  
  Examples

  TextChanged EventMethod($args.UndoAction)
  TextChanged EventMethodMultiParams(Text, $args.UndoAction)
  

  
  
  
  
• Validation Support. Validation is provided by a standard interface INotifyDataErrorInfo. An error message will be displayed on each platform.
  
  Examples

  Text Property, Mode=TwoWay, ValidatesOnNotifyDataErrors=True
  Text Property, Mode=TwoWay, ValidatesOnNotifyDataErrors=True, ValidatesOnExceptions=True
  Text Property, Mode=TwoWay, Validate=True //эквивалентно ValidatesOnNotifyDataErrors=True, ValidatesOnExceptions=True
  

  
  
  
  
• Advanced Binding on teams. If Binding is installed on a command, you can determine how the control will respond to the “availability” of the command; the command may make control ( Enabled = false) inactive if the command cannot be executed.
  
  Examples

  Click Command, ToggleEnabledState=false //не изменяет состояние контрола
  Click Command, ToggleEnabledState=true //изменяет состояние контрола

  
  
  
  
• Expanded validation support. The built-in method $GetErrors()will return validation errors of the entire form for all properties or errors for specific properties. The method is useful when there is a need to show the user errors on the form.
  
  Examples

  Text $GetErrors(Property).FirstOrDefault()
  Text $string.Join($Environment.NewLine, $GetErrors()) //Суммирует все ошибки в одну строку использую новую строку, как разделитель.

  
  
  
  
• Relative binding. Binding can be installed on the current control or on any other inside the visual control tree (analogue of the property RelativeSourcefor XAML platforms).
  Helper Methods:
  
  • $Element(ElementName) - Searches for an element named ElementName.
  • $Relative(Type), $Relative(Type, 1)- searches among parental controls with type Typeand (if necessary) taking into account the level of the parental element (second parameter).
  • $self - returns the current element on which Binding is set.
  
  
  Examples

  Text $Relative(Window).Title
  Text $self.ActualWidth
  Text $Element(NamedSlider).Value

  
  
  
  
• Support for attachable properties, events, and methods. Allows you to easily expand any type. For example, WinForms does DataGridViewnot have properties SelectedItem, but we can easily add it using the attached property:
  
  Example

  var member = AttachedBindingMember.CreateMember("SelectedItem",
      (info, view) =>
      {
          var row = view.CurrentRow;
          if (row == null)
              return null;
          return row.DataBoundItem;
      }, (info, view, item) =>
      {
          view.ClearSelection();
          if (item == null)
              return;
          for (int i = 0; i < view.Rows.Count; i++)
          {
              if (Equals(view.Rows[i].DataBoundItem, item))
              {
                  var row = view.Rows[i];
                  row.Selected = true;
              }
          }
      }, "CurrentCellChanged"); //CurrentCellChanged - событие в DataGridView, которое отвечает за изменение свойства.
  //Регистрация свойства
  BindingServiceProvider.MemberProvider.Register(member);

  
  
  
  
• Support for dynamic resources. You can add any object to resources, and then access it through binding. With the help of dynamic resources, it is easy to implement cross-platform localization of the application.
  
  Example

  //Регистрирует объект типа  MyResourceObject с именем i18n
  BindingServiceProvider.ResourceResolver.AddObject("i18n", new BindingResourceObject(new MyResourceObject()));
  //Пример Binding для доступа к ресурсу
  Text $i18n.MyResourceString

  
  
  
  
• Fluent syntax support.
  
  Example

  var textBox = new TextBox();
  var set = new BindingSet(textBox);
  set.Bind(window => window.Text).To(vm => vm.Property).TwoWay();
  set.Apply();

  
  
  
  
• Cross-platform. All necessary interfaces and classes are collected in a portable class library. Any platform will work with the same code, with the same capabilities.
• Performance. On platforms where there is a standard Binding implementation, MugenMvvmToolkit Binding is faster than the standard implementation, while providing much more features.

MVVM Implementation Features

• One or two classes that implement the interface INotifyPropertyChanged.
• A class that implements the interface ICommand.
• A class Messengerthat allows messaging between classes.
• Several helper methods for synchronizing UI threads.

• Navigation between ViewModelregardless of platform.
• Creation ViewModel, through a constructor with dependencies and parameters.
• Dynamic linking ViewModeland View.
• ViewModelLifecycle management View.
• Saving \ restoration of state ViewModeldepending on the platform.

Key Features of MugenMvvmToolkit:

• Cross-platform. At the moment, all major platforms on which C # can be used are supported. All necessary interfaces and classes are collected in a portable class library. Any platform will work with the same code, with the same capabilities.
• Unified code ViewModelfor different platforms.
• Integration with DI containers. MugenMvvmToolkit is not tied to a specific DI container; an interface is used for interaction IIocContainer. At the moment, there are implementations for three DI-containers MugenInjection, Autofac, Ninject. The list can be expanded by adding an interface implementation IIocContainerfor any other container.
• The presence of several base classes ViewModelfor various situations.
  
  • ViewModelBase- a base class for everyone ViewModel, contains methods for creating others ViewModel, methods for messaging, methods and properties IsBusy, BusyMessagefor managing the status of asynchronous operations.
  • CloseableViewModel- inherited from ViewModelBase, implements an interface ICloseableViewModelthat allows you to control the closing process ViewModel.
  • ValidatableViewModel- inherited from CloseableViewModel, contains methods and properties for validation, implements an interface INotifyDataErrorInfofor notifying Binding about errors.
  • EditableViewModel- inherited from ValidatableViewModel, allows you to edit and validate the data model, monitors the state of the object, allows you to undo the changes.
  • WorkspaceViewModel, WorkspaceViewModel- inherited from CloseableViewModel, contains properties IsSelectedand DisplayName- for convenient display ViewModelin the interface. Implements an interface that allows access to , through the interface . Implements an interface that allows you to track the navigation process for the methods , , .IViewAwareViewModelViewIViewINavigableViewModelViewModelOnNavigatedFromOnNavigatingFromOnNavigatedTo
  • GridViewModel- inherited from ViewModelBase, allows you to work with collections of various objects.
  • MultiViewModel- inherited from CloseableViewModel, allows you to work with collections of others ViewModel, well suited for binding to TabControl.
  
  
• MugenMvvmToolkit does not use ViewModelLocatorto create ViewModel. All ViewModelare created using the DI container, the ViewModelinterface is responsible for the creation IViewModelProvider.
  
  An example of creating and interacting ViewModel

   public class ItemViewModel : ViewModelBase
   {    
  	 public ItemViewModel(ISomeService service)
  	 {        
  	 }
  	 public void InitializeValue()
  	 {
  	 }
   }
   public class MainViewModel : ViewModelBase
   {
  	 public void CreateViewModelMethod()
  	 {
  		 //Создание ViewModel
  		 var viewModel = GetViewModel();
  		 //Использование любого метода, свойства, события и т.д.
  		 viewModel.InitializeValue();
  	 }
   }

  
  
  
  
• Comparison Viewwith ViewModeloccurs dynamically. The interface is responsible for the mapping IViewMappingProvider; the default naming convention is used. To ViewModeldelete the following end:
  "ViewModel", "Vm",
  and for View:
  "ActivityView", "FragmentView", "WindowView", "PageView", "FormView", "Form", "View", "V", "Activity", "Fragment", "Page", "Window"
  (you can expand the lists) and if it is then the names are the same, it is believed that Viewcorresponds ViewModel.
  Matching example:
  MainViewModel, MainVm -> MainActivityView, MainFragmentView, MainWindowView и т.д.
  If you want to explicitly set Viewfor ViewModel, you can use ViewModelAttribute(in this case, the naming convention is ignored):
  

  [ViewModel (typeof(MainViewModel))]
  public partial class MainWindow : Window

  
  You can also specify a name for Viewand then use it when creating / displaying ViewModel:
  
  Example

  [ViewModel (typeof(ItemViewModel), “ViewName”)]
  public partial class ItemView : Window
  //Создание ViewModel с явно заданным именем View
  //В момент показа ViewModel система будет искать View с именем ViewName
  var viewModel = GetViewModel(parameters: NavigationConstants.ViewName.ToValue("ViewName"));
  //Создание ViewModel
  var viewModel = GetViewModel();
  //Явно указываем, что для показа ViewModel необходимо использовать View с именем ViewName
  viewModel.ShowAsync(NavigationConstants.ViewName.ToValue("ViewName"));

  
  
  
  
• Powerful validation system, support for asynchronous validation, easy integration with existing validation frameworks.
• Support save / restore state ViewModel. If it ViewModelhas a state that needs to be saved, it must implement an interface IHasStatethat has two methods LoadStateand SaveState. The system will automatically call these methods depending on the life cycle of the application and the current platform.
  
  Example

  private static readonly DataConstant StringState = DataConstant.Create(() => StringState, true);
  public void LoadState(IDataContext state)
  {
      //вы можете использовать строго типизированные ключи
      state.AddOrUpdate(StringState, "Constant key");
      //вы также можете использовать обычные строки для ключей
      state.AddOrUpdate("Test", "String key");
  }
  public void SaveState(IDataContext state)
  {
      string data = state.GetData(StringState);
      var s = state.GetData("Test");
  }
  

  
  
  
  

Navigation

//При создании мы можем передавать любые параметры в конструктор
var mainWindow = new MainWindow();
//Здесь можно писать любой код ининциализаии и взаимодействия с окном.
mainWindow.Init(args);
if (!mainWindow.ShowDialog().GetValueOrDefault())
    return;
//Этот код продолжит выполнение после закрытия окна, и мы легко можем получить результат.

//Мы не можем сами создать Activity, мы лишь указываем тип, а система сама создает ее.
var page2 = new Intent (this, typeof(Page2));
//Мы можем передавать только простые параметры
page2.PutExtra ("arg1", arg)
StartActivity (page2);
//Нужно перезагрузить метод, чтобы узнать, когда завершится запущенная Activity

//Все те же ограничения что и на Android.
NavigationService.Navigate(typeof(Page2), arg);

ShowViewModel(new DetailParameters() { Index = 2 });

public void Init(DetailParameters parameters)
{
    // use the parameters here
}

public class Vm2 : ViewModelBase
{
    public void InitFromVm1()
    {
    }
    public object GetResult()
    {
        return null;
    }
}
public class Vm1 : ViewModelBase
{
    public async void Open()
    {
        var vm2 = GetViewModel();
        //Здесь вы можете передать любые параметры, вызвать любые методы и т.д
        vm2.InitFromVm1();
        //Возвращает интерфейс типа IAsyncOperation,
        //который позволяет зарегестрировать делегат который будет вызван при закрытии Vm2
        IAsyncOperation asyncOperation = vm2.ShowAsync(Vm2CloseCallback);
        //Еще один способ добавить делегат
        asyncOperation.ContinueWith(Vm2CloseCallback);
        //Или вы можете использовать ключевое слово await
        await asyncOperation;
        //Этот код будет выполнен после закрытия Vm2
        //Получаем результат после закрытия
        var result = vm2.GetResult();
    }
    private void Vm2CloseCallback(IOperationResult operationResult)
    {
        //Получаем результат после закрытия
        var result = ((Vm2)operationResult.Source).GetResult();
    }
    private void Vm2CloseCallback(Vm2 vm2, IOperationResult operationResult)
    {
        //Получаем результат после закрытия
        var result = vm2.GetResult();
    }
}

WPF and SL

• Dialog / window navigation support for WPF. If you map Windowto any ViewModel, then when you call the method ShowAsync, a dialog box will be displayed.
• Class navigation support ChildWindowfor SL. If you map ChildWindowto any ViewModel, then when you call the method ShowAsync, a dialog box will be displayed.
• Support page navigation, for WPF - NavigationWindow, for SL - Frame.
• Validation support using the standard System.Windows.Controls.Validation.Errors property .

WinRT and Windows phone

• Support for page navigation using the class Page. If you map Pageto any ViewModel, then when you call the method ShowAsync, a new page will be displayed.
• Validation support using the standard System.Windows.Controls.Validation.Errors property .

xmlns:markupExtensions="clr-namespace:MugenMvvmToolkit.MarkupExtensions;assembly=MugenMvvmToolkit.WinPhone"
xmlns:markupExtensions="using:MugenMvvmToolkit.MarkupExtensions"

Winforms

• MugenMvvmToolkit provides a convenient xml editor for Binding.
• Support DataTemplateSelectorfor Binding, an analogue DataTemplateSelectorfor Xaml platforms.
• Support navigation using the class Form. If you map Formto any ViewModel, then when you call the method ShowAsync, a dialog box will be displayed.
• Validation support using the standard class System.Windows.Forms.ErrorProvider.

1. Create a class that inherits from the Binder class:
   

   public class ViewBinder : Binder
   {
       public ViewBinder()
       {
       }
       public ViewBinder(IContainer container)
           : base(container)
       {
       }
   }
   

   
   
2. Compile the project, open the designer with the desired form, go to the Toolbox tab, the class should appear there ViewBinder
3. Add it to the form, after that you can add Binding using the property Bindings.

Xamarin.Android

• Поддержка работы с Activity, для всех стандартных Activity существует реализация с префиксом Mvvm, для работы вам необходимо наследоваться не от стандартных Activity, а с префиксом Mvvm. Если вы сопоставите Activity с какой-либо ViewModel, то при вызове метода ShowAsync, будет совершена навигация на новую Activity этого типа.
• Поддержка работы с Fragment, для всех стандартных Fragment существует реализация с префиксом Mvvm, для работы вам необходимо наследоваться не от стандартных Fragment, а с префиксом Mvvm. Если вы сопоставите MvvmDialogFragment с какой-либо ViewModel, то при вызове метода ShowAsync, будет показано диалоговое окно.
• State management for Activityand Fragment. State Activityand Fragmentis already being tracked, so you do not need to manually invoke methods to save / restore ViewModel.
• The ability to use back stack fragmentnavigation.
• Binding support using layout (xml markup). To use Binding on Android, you need to add the following namespace in the markup file xmlns:pkg="http://schemas.android.com/apk/res-auto", then you can add Binding to any control using the attributeBind
  
  Example

  
  
  
  
• Binding support for ActionBar, Toolbar, PopupMenuand OptionsMenu.
• Support DataTemplateSelectorfor Binding, an analogue DataTemplateSelectorfor Xaml platforms.
• Validation using a standard property TextView.Error.

Xamarin.iOS

• Support for working with UIViewController, for all standard UIViewControllerones there is an implementation with the Mvvm prefix, for work you need to inherit not from the standard ones UIViewController, but with the Mvvm prefix. If you map UIViewControllerto any ViewModel, then when you call the method ShowAsync, navigation will be made to a new one of UIViewControllerthis type.
• Support modal navigation for UIViewController.
• State management for UIViewController. Statuses are UIViewControlleralready monitored, so you do not need to manually call methods to save / restore ViewModel.
• Support DataTemplateSelectorfor Binding, an analogue DataTemplateSelectorfor Xaml platforms.
• Library support MonoTouch.Dialog.

Xamarin.Forms

• Поддержка страничной навигации с использованием класса Page. Если вы сопоставите Page с какой-либо ViewModel, то при вызове метода ShowAsync, будет показана новая страница.
• Поддержка модальной навигации с использованием класса Page.
• Поддержка Binding с использованием Xaml-разметки. MugenMvvmToolkit предоставляет класс DataBindingExtension и attached property View.Bind, для работы с Binding. Для использования Binding необходимо в файле Xaml-разметки добавить следующее пространство имен xmlns:mugen="clr-namespace:MugenMvvmToolkit.MarkupExtensions;assembly=MugenMvvmToolkit.Xamarin.Forms"

Заключение

References:

• Repository with project
• Examples
• Plugin for Fody
• Nuget