.NET tells me TypeLoadException: violates the constraint of type parameter 'T' while my code clearly doesn't violate it

I am trying to initialize an object of DataEditor<Student>, where my DataEditor<T> class implements interface IDataEditor<T> where T : IEditableO开发者_JS百科bject.

DataEditor<Student> editor = GetEditorFor(student);

During runtime, I got a TypeLoadException saying: GenericArguments[0], 'Namespace.Data.Student', on 'Namespace.IDataEditor`1[T]' violates the constraint of type parameter 'T'. The exception happens on the line above, before it even goes inside the GetEditorFor method.

The only constraint on T is IEditableObject, and my Student class clearly implements it (I double checked the interface spelling, namespace, etc.), and also the compiler doesn't give me any error, so I have no idea why this error happens on runtime.

If I remove the IEditableObject constraint, the code runs without this exception, but my logic depends on the class being an IEditableObject, so it is not an option.

Any idea why this happens and how to fix it?

These pages seems to be related, but I still don't know the solution

• https://connect.microsoft.com/VisualStudio/feedback/details/270717/reflection-emit-chokes-on-method-type-parameters
• http://bytes.com/topic/c-sharp/answers/478595-reflection-generics-could-anyone-confirm-deny-bug

Is this a bug in .NET? Has anyone found a workaround?

Edit: declaration as requested

public class DataEditor<T> : ViewModel, IDataEditor<T> where T :  IEditableObject

public interface IDataEditor<T> : IDataEditor 
    where T :  IEditableObject

My project could not build because of the same error. Even if I did not use any of this generic typed class. Its assembly was just referenced.

When I delete the accessor file of it, problem solved. If you do not need accessor, deleting it may be a solution.

This answer may useful for someone.

What happens is that Student does not implement IEditableObject, the GetEditorFor method probably has a where clause where T must be IEditableObject, and the T that you are passing is Studentand not IDataEditor.

That's why you're getting this error, you're violating the method signature sending a T that is not IEditableObject.

You should either implement IEditableObjectinto the Studentclass, or remove the where T : IEditableObject clause.