Question

I’ve been using .net MVC for a year or two now, and this question has always been unanswered in my books. Let me demonstrate a very simple example

PersonViewModel

public class PersonViewModel
{
    public Person person { get; set; } //person is a db generated object
    public SelectList jobtypes { get; set; } // drop down list for this view 
}

PersonController

public ActionResult Edit( int id )
{
    PersonViewModel model = new PersonViewModel();
    model.person = db.GetPerson(id); //get a person from the db
    model.jobtypes = GetThemJobTypes();
    return View(model);
}

now the question is which of the following i should do?

[HttpPost]
public ActionResult Edit ( PersonViewModel model )
{
     Person person = db.GetPerson(model.person.personid);

     person.firstname = model.person.firstname;
     person.lastname = model.person.lastname;
     person.jobtypeid = model.person.jobtypeid;
     person.save();

     person.favoritetoy.name = model.person.favoritetoy.name;
     person.favoritetoy.save();
}

OR

[HttpPost]
public ActionResult Edit (int id, FormCollection formValues)
{
     Person person = db.GetPerson(id);
     UpdateModel(person, "person"); 
     person.save()

     UpdateModel(person.favoritetoy, "favoritetoy");
     person.favoritetoy.save()
}

It seems like the formcollection method with updatemodel is the method of choice everywhere around the web. What i’m a little conflicted with is that we already have a ViewModel with the fields we want, why use the formcollection again? Many has also pointed out to strictly use the viewmodel in the post, but I haven’t seen good example of an update to db models using that method.

What is the Intended way of updating db objects?

Answer 1

There’s really no intended way. Unlike Ruby on Rails the ASP.Net MVC framework doesn’t tie you into any particular pattern for your controller and model interactions. Personally I use something closer to the first because it’s more likely to cause a compiler error if you make a mistake than a runtime error. I would recommend moving this code to a location other than your controller method however as it will grow quickly out of hand.