Uno Platform ViewModelLocator - autofac

Question

I'm testing uno platform solution to see if it's flexible enough and can integrate pre existing autofac (6.2.0) and Autofac.Extras.CommonServiceLocator(6.0.1) stuff in it.
I want to add the ViewModelLocator to auto resolve view models. it's working with UWP and wpf project, but not with droid or WASM.
I added in shared app.xaml the resource
<Application
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<XamlControlsResources xmlns="using:Microsoft.UI.Xaml.Controls" />
<!-- #Region MVM light view model locator -->
<ResourceDictionary>
<local:ViewModelLocator x:Key="ViewModelLocator" d:IsDataSource="True" />
</ResourceDictionary>
<!-- #Endregion -->
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>
</Application>
In the mainpage.xaml
DataContext="{Binding [TestViewModel], Source={StaticResource ViewModelLocator}}"
whit this configuration the constructor is called at startup where I also want to set up Inversion of control stuff
public ViewModelLocator()
{
this._container = IOCContainerConfig.Configure();
var serviceLocator = new AutofacServiceLocator(this._container);
ServiceLocator.SetLocatorProvider(() => serviceLocator);
//this._dbContext = serviceLocator.GetInstance<IContext>();
//TestDbConnection(this._dbContext);
}
As said this is not working with other kind of projects like droid or wasm the constructor of the locator is never called but I don-t have errors, just page is loaded without the viewmodel behind.
Any ideas or tips to make it working for all projects?

Answer 1

Depending on the type of resource, Uno Platform is initializing some resources in a ResourceDictionary lazily only when they are accessed. This is done as a performance optimization.
To guarantee that the ViewModelLocator constructor is always called on all platforms, it may be better to call it from code, eg from the App constructor in App.xaml.cs.