I have an AccountModel  and a page where the user can upload a file.  What I would like to have happen is when the user uploads the file. The PageController does something like the following.  this is a quick attempt just written in the question to illustrate my question.public class PageController : Controller {  private Service service;      public ActionResult Upload(HttpPostedFileBase f){         service.savefile(f,_AccountModel_whatever.currentlyloggedinuser.taxid)          }}public class Service{// abunch of validation and error checking to make sure the file is good to store}Wouldn't this approach be in bad practice? Since I'm making my controller dependent on the existence of th AccountModel?  This will become a HUGE program over the next few years, and I really want to maximize the quality of the framework now.
What's the correct approach for passing data from several models into a service?
c#;asp.net;mvc