I have a ViewModel which has a `[key]` property and i would like to get that from an instance of that view model.

My code looks something like this (fictional models)

```
class AddressViewModel
{
    [Key]
    [ScaffoldColumn(false)]
    public int UserID { get; set; } // Foreignkey to UserViewModel
}

// ... somewhere else i do:
var addressModel = new AddressViewModel();
addressModel.HowToGetTheKey..??

```

So i need to get the `UserID`(in this case) from the ViewModel. How can i do this?