Use MVVM Light View Model Locator with Child Window in Silverlight 4

Question

I want to use the View Model Locator in a Child Window. Problem is this don't work:

<controls:ChildWindow x:Class="Views.PopupViews.AddAlert"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
       xmlns:controls="clr namespace:System.Windows.Controls;assembly=System.Windows.Controls"
       DataContext="{Binding AddAlert, Source={StaticResource Locator}}>

I get the error: Cannot find a Resource with the Name/Key Locator

you are missing "" in the end. I fixed it, try it out: DataContext="{Binding AddAlert, Source={StaticResource Locator}}"> — Rumplin, Aug 17 '11 at 12:31

score 1 · Answer 1 · answered Aug 17 '11 at 12:28

There is no trick to binding a child window to a static view model using the locator pattern. My guess is your DataContext is wrong.

Check: Make sure you have an "AddAlert" property defined in your locator class. Something like:

    private static AddAlertViewModel _AddAlertViewModel;

    /// <summary>
    /// Gets the ViewModelPropertyName property.
    /// </summary>
    public static AddAlertViewModel AddAlertViewModelStatic
    {
        get
        {
            if (_AddAlertViewModel == null)
            {
                CreateAddAlertViewModel();
            }

            return _AddAlertViewModel;
        }
    }

    /// <summary>
    /// THIS PROPERTY IS WHAT YOU NEED TO REFERENCE IN YOUR XAML
    /// </summary>
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1822:MarkMembersAsStatic", Justification = "This non-static member is needed for data binding purposes.")]
    public AddAlertViewModel AddAlert
    {
        get
        {
            return AddAlertViewModelStatic;
        }
    }

And of course make sure your view model locator is instantiated in your App.xaml file:

  <vm:MyModelLocator xmlns:vm="clr-namespace:MyAppNamespace" x:Key="Locator" />

score 1 · Accepted Answer · answered Oct 10 '11 at 14:41

Ok the reason why it don't works is my childWindow is created inside the ctor of an IApplicationService.

This popupService is declared in the App.xaml:

<Application.Resources>
    <ResourceDictionary>
        <vm:ViewModelLocator xmlns:vm="clr-namespace:Client.ViewModel" x:Key="Locator" />
        <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary Source="Assets/Styles.xaml"/>
        </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
</Application.Resources>
<Application.ApplicationLifetimeObjects>
    <popup:myPopupService/>
</Application.ApplicationLifetimeObjects>

Apparently, the view was created before the app resources !

Use MVVM Light View Model Locator with Child Window in Silverlight 4

2 Answers2