Beginning Windows 8 Data Development: Using C# and JavaScript by Vinodh Kumar

Author:Vinodh Kumar [Kumar, Vinodh]
Language: eng
Format: epub, pdf
Tags: C#, Computers, Programming, Microsoft, Programming Languages
ISBN: 9781430249931
Google: jRXbAAAAQBAJ
Publisher: Apress
Published: 2013-09-10T00:00:00+00:00

ViewModel

The ViewModel folder consists of ViewModelLocator and two ViewModels: MainViewModel and BillViewModel. ViewModelLocator is a repository of ViewModels enabled by MVVM Light that locates the ViewModel from inside XAML and connects it to the View DataContent.

The App.xaml defines a global instance of the locator as shown in Listing 6-9, and individual views can bind their DataContent to properties of the locator that serve up the individual ViewModels.

Listing 6-9. Global Instance of the ViewModelLocator in App.xaml

<Application.Resources>

<vm:ViewModelLocator x:Key="Locator"

d:IsDataSource="True" />

</Application.Resources>

MVVM Light also made it simple to register Services and ViewModels by including a simple IOC container along with the framework, as shown in Listing 6-10.

Listing 6-10. SimpleIOC Container Registers DataService, NavigationService, MainViewModel, and BillViewModel

public class ViewModelLocator

{

static ViewModelLocator()

{

ServiceLocator.SetLocatorProvider(() => SimpleIoc.Default);

SimpleIoc.Default.Register<IDataService, DataService>();

SimpleIoc.Default.Register<INavigationService>(() => new NavigationService());

SimpleIoc.Default.Register<MainViewModel>();

SimpleIoc.Default.Register<BillViewModel>();

}

[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance",

"CA1822:MarkMembersAsStatic",

Justification = "This non-static member is needed for data binding purposes.")]

public MainViewModel Main

{

get

{

return ServiceLocator.Current.GetInstance<MainViewModel>();

}

}

[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance",

"CA1822:MarkMembersAsStatic",

Justification = "This non-static member is needed for data binding purposes.")]

public BillViewModel Bill

{

get

{

return ServiceLocator.Current.GetInstance<BillViewModel>();

}

}

}

As shown in Listing 6-11, the ViewModels are exposed as properties of the ViewModelLocator and can be databound in XAML to the View DataContext.

Listing 6-11. MainViewModel Databound to the MainPage.xaml Datacontext

<Page x:Class="BillReminder.MainPage" xmlns=" http://schemas.microsoft.com/winfx/2006/xaml/presentation "

xmlns:x=" http://schemas.microsoft.com/winfx/2006/xaml "

xmlns:d=" http://schemas.microsoft.com/expression/blend/2008 "

xmlns:mc=" http://schemas.openxmlformats.org/markup-compatibility/2006 "

xmlns:ignore=" http://www.ignore.com "

mc:Ignorable="d ignore"

d:DesignHeight="768"

d:DesignWidth="1366"

DataContext="{Binding Main, Source={StaticResource Locator}}">

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