.NET: Unable to cast object to interface it implements

user_193327 0
Viewed 30963

I have a class (TabControlH60) that both inherits from a base class (UserControl) and implements an interface (IFrameworkClient). I instantiate the object using the .NET Activator class. With the returned instance, I can cast to the UserControl base class, but not to the interface. The exception I get is below the code snipet. How do I cast to the interface?

object obj = Activator.CreateInstance(objType);
Type[] interfaces = obj.GetType().GetInterfaces(); // contains IFrameworkClient

m_Client = (UserControl)obj;                 // base class cast works
IFrameworkClient fc = (IFrameworkClient)obj; // interface cast fails

// Note: The (IFrameworkClient)obj cast works fine in the debugger Watch window.
{"Unable to cast object of type 'FPG.H60.AFF.TabControlH60' to type 
    'FPG.AFF.Interfaces.IFrameworkClient'."}
base-class activator casting interface c#
9 Answers

Define IFrameworkClient Interface in independent namespace (must be have namespace) of independent project (class library).Then add refrence of the class library to Control project and main project

user_5919230

I ran into same issue and I just added the following code

private void LoadAssemblyPlugins(string dll)

    Assembly ass = AppDomain.CurrentDomain.GetAssemblies()
        .FirstOrDefault(a => new Uri(a.CodeBase).Equals(new Uri(dll)));

   if (ass == null)
       // Load it here
       // use activator here

Although, in production it will never be a problem, in unit test it was but now I don't need to load it again and create a "different type"

user_17044580
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