MVC View Model Get Child Object

Question

I have a main Contact and ContactViewModel . How do I get contact model and update it to the database ?

  [HttpPost]  
    public ActionResult EditContact(ContactFormViewModel contactView) {  

    }

I was doing like this before I needed ViewModel

[HttpPost]
    public ActionResult EditContact(int id, FormCollection collection) {  
        Contact contact = repository.GetContactById(id);  
                      if (TryUpdateModel(contact, "Contact")) {  
                           repository.Save();  
                           return RedirectToAction("Index");   
 return View(new ContactFormView Model(contact));  
            }   
            }       

Answer 1

It's a bit easier when you have a view model (you can forget about FormCollection and TryUpdateModel):

[HttpPost]
public ActionResult EditContact(ContactViewModel contact) 
{  
    if (ModelState.IsValid)
    {
        // the model is valid => we can save it to the database
        Contact contact = mapper.Map<ContactViewModel, Contact>(contact);
        repository.Save(contact);  
        return RedirectToAction("Index");   
    }
    // redisplay the form to fix validation errors
    return View(contact);
}

where mapper converts between the view model and models. AutoMapper is a great choice for this task.