Question

I have a WPF container application (with ContentControl host) and a containee application (UserControl). Both are oblivious of each other.

Only one XML config file holds the string dllpath of the containee’s DLL and full namespace name of the ViewModelClass inside the containee.

A generic code in container resolves containee’s assembly (Assembly.LoadFrom(dllpath)) and creates the viewmodel’s instance using Activator.CreateInstance(vmType). when this viewmodel is hosted inside the ContentControl of the container, and relevant vierwmodel specific ResourceDictionary is added to ContentControl.Resources.MergedDictionaries of the content control of container, so the view loads fine.

Now my containee has to host the WPF DataGrid using assembly reference of WPFToolkit.dll from my local C:\Lib folder.

The Copy Local reference to the WPFToolkit.dll is added to the .csproj file of the containee’s project and its only referred in the UserControl.XAML using its XAML namepsace. This way my bin\debug folder in my containee application, gets the WPFToolkit.dll copied.

XAML:

xmlns:Controls="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit"
<Controls:DataGrid ItemsSource="{Binding AssetList}" ... />

Issue:
The moment the ViewModel (i.e. the containee’s usercontrol) tries to load itself I get this error.

“Cannot find type ‘Microsoft.Windows.Controls.DataGrid’. The assembly used when compiling might be different than that used when loading and the type is missing.”

Hence I tried to load the referenced assemblies of the containee’s assembly (myAssembly.GetReferencedAssemblies()) before the viewmodel is hosted. But WPFToolkit isnt there in that list of assemblies!

Strange thing is I have another dll referred called Logger.dll in the containee codebase but this one is implemented using C# code behind. So I get its reference correctly resolved in myAssembly.GetReferencedAssemblies().

So does that mean BAML references of assemblies are never resolvable by GetReferencedAssemblies?

EDIT:

Forgot to add I did a post build event in containee to xcopy all bin\debug\*.* to container’s ‘bin\debug’. It works then. But I dont want all containee’s being copied like that to the container. Container should be oblivious of containee applications (even dlls) until runtime.

Answer 1

Solution to your problem might be to add handler to AppDomain.AssemblyResolve event. This event is called as last resort when an assembly is needed and your application cannot find is in an ordinary way. This is the place where you can customize this process by scanning your containees folders (read from config so no hard relationship) in an attempt to find needed dll.