WinRT Data Binding Using MVVM

How to bind Windows 8 XAML to a View Model. Although this post is based on an example using MVVM Cross, it will work for any MVVM framework, or even a customised one.

The Problem

I have a collection of data that I want to display in a customised format. My architecture is MVVM (using MVVM Cross).

Architecture

The principle here is that my data is stored in a model, but shaped in the ViewModel into a digestible format for the view. In my specific example, I have a list of people, and based on a specific criteria, I want to display a selection of these people in the view. For the sake of this article, I want to display people with a name starting with “D”.

Implementation

My model looks something like this:

    public class Person
    {
        #region Basic attributes
        public string Name { get; set; }

When my ViewModel is shown, I override an initialise method. Whilst this is not part of MVVM Cross per-se, it is basically a call to a custom initialise from the default `Init`:

private IEnumerable<Person> _people;
public IEnumerable<Person> People
{
    get { return _people; }
    set
    {
        _people = value;
        RaisePropertyChanged(() => People);
    }
}

// Override custom init method
protected override void RealInit(NavigationParameter parameter)
{            
    var population = Mvx.Resolve<Population>();
    People = population.Where(p => p.Name.StartsWith("D"));
}

So, my ViewModel now contains the correct, shaped data, I can just bind this:

    <Page.Resources>
        <DataTemplate x:Name="PeopleTemplate">
            <StackPanel Orientation="Horizontal">
                <TextBlock Text="{Binding Name}"/>
            </StackPanel>
        </DataTemplate>    
    </Page.Resources>

    …


    <ListView x:Name="ItemListView" 
                      ItemsSource="{Binding People}"
                      Width="Auto" Height="Auto" 
                      ItemTemplate="{StaticResource PeopleTemplate}" 
                      ShowsScrollingPlaceholders="False"                          
                      />

And that should work.

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