Thank you for the update. I am glad that currently, everything works fine on your side.
Let me just add that the error you experience is caused from the fact that both classes have DatabaseServerCalculated set for the identity mechanism. You can avoid it by using this setting only for the Media class.
Additionally, consuming the model in the necessary way is provided by the isManaged
properties that can be set for the navigation properties of the classes. Here
you can find how to insert related objects in the database and here
- how to delete related objects.
If you have other questions or if you experience difficulties, do not hesitate to get back to us.
the Telerik team