用参数在MVVM光中打开新窗口的最佳实践

I am fairly new to mvvm and mvvm light, but I think I understand the general idea of it. What I don't understand is if I want to open a new window, but that window needs data from the caller what is the best practice to get that data to the new window? If I pass the data to the constructor then that means I need code in the code behind to pass it to the view model. I can't use messaging, because it isn't basic data. Thanks in advance.I am fairly new to mvvm and mvvm light, but I t