The Evil Greebo The Evil Greebo - 10 months ago 128
C# Question

The designer could not be shown for this file because none of the classes within it can be designed

We have the following shared component:

public class OurServiceBase : System.ServiceProcess.ServiceBase

This class has functionality we want in all our downstream services, such as standardized execution scheduling and logging functionality.

In a new project, I add the following:

public class MyService : System.ServiceProcess.ServiceBase

In the Windows Designer, the class shows properly.

When I change the service to derive from OurServiceBase

public class MyService : OurSharedLibrary.OurServiceBase

The designer stops working:

Error screenshot

The full error is:
The designer could not be shown for this file because none of the classes within it can be designed. The designer inspected the following classes in the file: EmailProcessor --- The base class 'OurSharedLibrary.CienaServiceBase' could not be loaded. Ensure the assembly has been referenced and that all projects have been built.

The proper assemblies are referenced, the project builds. I don't understand why the designer is flipping out over this since my service ultimately does derive from a designable class.

Any suggestions would be most welcome.

Bit more information - the call stack from the designer when it renders the error about not being able to design the derived service:

at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.EnsureDocument(IDesignerSerializationManager manager)
at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager manager)
at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager serializationManager)
at System.ComponentModel.Design.Serialization.BasicDesignerLoader.BeginLoad(IDesignerLoaderHost host)

7/19/2011 2:34PM EDT New discovery.

Class "OurServiceBase" exists in a separate project (usually referenced as a DLL only). On a whim, I copied the base class file into my project, built, and opened the designer. It worked! When I removed the base class file again and returned to the external DLL reference, the designer broke again.

Answer Source

Your best bet would be to start with a version of OurServiceBase with no functionality and see if you can design MyService. If so, then slowly add back functionality until it breaks.

Since it looks like Visual Studio is having a problem serializing one of the members of OurServiceBase.