Prism does not call the correct contructor

[Esterl-Christian]

Hi together,

I would like to inspire my colleagues to use Prism.DryIoc for WPF. I have been asked to integrate Prism into an existing product in order to demonstrate prisms power. That is, the class design of this project already exists and cannot be easily changed.
While working on the migration I saw something strange, what I want to discuss with you.

It would be great for me if you could spare a moment.

Problem description:
Prism.DryIoC function Contaier.Resolve calls the wrong constructor in the SampleType class.I expect the default ctor to be called.
I would like to show you this with a small example.

Example code:

=============================================================

// This is my registered type
public class SampleType
{
// Default constructor without parameter
public SampleType()
{
// THIS CTOR NEVER GET’S CALLED WHILE RESOLVE THE TYPE !!!
}

       // Second constructor with an concrete type (AnyType) as parameter (not an interface of this type!)
      // HINT: AnyType is not shown in this example. Think about it like a standard class without interfaces overwritten ctors and so on!!!

public SampleType(AnyType concreteType)
{
// INSTEAD THIS CTOR GET’S CALLED WITH A BLANK INSTANCE OF AnyType while resolving SampleType.
// (AnyType WAS NOT REGISTERED SO I EXPECT PRISM TO TAKE THE DEFAULT ctor)
}
}

=============================================================

// The implementation of prism in App class
public class App:PrismApplication
{

   protected override void RegisterTypes(IContainerRegistry containerRegistry)
    {
        // Here I do the registration of the SampleType (see above)
        containerRegistry.Register< SampleType >();
    }

   public void TestCode()
    {
        // Here I do the resolve of the SampleType (see above). The problem happens here
        // The class AnyType get’s instantiated by prism although it isn’t registered  Afterward the second ctor of SampleType get’s called  WHY?
        var instance = Container.Resolve< SampleType >();
    }

}

Thanks very much for your answer
Greetings Christian

[Esterl-Christian]

I got the following answer from Dan Siegel

This is expected behavior. Prism ensures that the DI Container will automatically resolve any concrete type. It must function this way because of Prism’s ViewModelLocator which will resolve your ViewModel (a concrete type) automatically despite it not being registered with the container.
Note that it is best practice to only have a single constructor, and that DI Containers will always default to a constructor with parameters over one without. If you were injecting an interface instead of a concrete type there then it would fallback to the default constructor if the interface wasn’t registered.