Question

In my update actions I am doing this:

[HttpPost]
public ActionResult Update()
{

  if(Request.Form["..."])
  {

  }
  ..

}

So I am grabbing the ID of the entity, then loading it, then updating the properties based on the posted form values.

I’m using MVC2.

How should I be doing this as I read about model state but not sure how to start?

I want to refactor to make this right.

Update

My viewmodel looks like:

public class SomeViewModel
{
   public User User {get; set;}
}

Answer 1

You should define a view model containing all the necessary information that the view will send:

public class MyViewModel
{
    public int Foo { get; set; }

    [Required]
    public string Bar { get; set; }

    [Required]
    public DateTime? Baz { get; set; }
}

and then have your controller action take this view model as parameter:

[HttpPost]
public ActionResult Update(MyViewModel model)
{
    if (!ModelState.IsValid) 
    {
        // validation failed (the user left the Bar field empty) =>
        // we redisplay the view so that he can fix the errors
        return View(model);
    }

    // at this stage we know that the model is valid =>
    // we could do some processing. The model.Foo and model.Bar
    // properties will contain the values entered by the user in the 
    // corresponding form fields so that you don't need to fetch them
    // manually from the Request. The default model binder will take
    // care of this

    ...
}