How can I deal with this MEF related ReflectionTypeLoadException exception?

Question

I have three projects, viz Shell.Core , Shell , and Services.Employees . Shell imports parts from Services.Employees , ie the latter project is external and not referenced in any of the solution projects. As well as Shell , `Shell.Core' is also a WPF application, not a class library. I started it as that project type for DevExpress to include all the correct references for me, as it defines certain shared UI components.

Services.Employees does reference Core , which defines certain base classes it uses. Now, when the startup application, Shell , it should load Core , and then it does MEF composition, loading Services.Employees parts from a DirectoryCatalog, but MEF sees the dependencies on Core and wants to load them from that catalogue, although the host application already references these Core dependencies.

As example, when I try composition, I get an error like:

Exception: 'TypeLoadException': Could not load type 'Shell.Core.MappedViewModel`1' from assembly 'XTime900.Shell.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.

What are my ways out of this? Should I also import Shell.Core.MappedViewModel , although it is already in a referenced project? Should I convert Core to a class library, so it will appear in the catalogue directory as a DLL and MEF will load it as a dependency of Services.Employees ? Is there any other way to get around this sticky little problem?

Answer 1

It looks like this happened. Shell.Core.MappedViewModel1, referenced by the plugins, loaded the ViewModel types. Then, the MEF plugins referenced this project, and during composition, couldn't find the right objects. When I factored View Models out into a separate project, referenced by both Shell.Core.MappedViewModel1, referenced by the plugins, loaded the ViewModel types. Then, the MEF plugins referenced this project, and during composition, couldn't find the right objects. When I factored View Models out into a separate project, referenced by both Core` and the MEF imports, all worked well again.