CODEWITHSUNDEEP
asp.net-mvc
Dave Mateer
Dave Mateer

Reputation: 6626

ASP.NET MVC - State and Architecture

After a pair programming session, an interesting question came up which I think I know the answer for.

Question: Is there any other desired way in ASP.NET MVC to retain 'state' other than writing to database or a text file?

I'm going to define state here to mean that we have a collection of person objects, we create a new one, and go to another page, and expect to see the newly created person. (so no Ajax)

My thoughts are we don't want any kung-fu ViewState or other mechanisms, this framework is about going back to a stateless web.

Upvotes: 3

Views: 2995

Answers (3)

John Farrell
John Farrell

Reputation: 24754

My thoughts are we don't want any kung-fu ViewState or other mechanisms, this framework is about going back to a stateless web.

The example you provided is pretty easy to do without any sort of "view state kung fu" using capabilities that are already in MVC. "User adds a person and sees that on the next screen." Let me code up a simple PersonController that does exactly what you want:

public ActionResult Add()
{
    return View(new Person());
}

[HttpPost]
public ActionResult Add(PersonViewModel myNewPersonViewModel)
{
    //validate, user entered everything correctly
    if(!ModelState.IsValid)
        return View();

    //map model to my database/entity/domain object
    var myNewPerson = new Person()
    {
        FirstName = myNewPersonViewModel.FirstName,
        LastName = myNewPersonViewModel.LastName
    }

    // 1. maintains person state, sends the user to the next view in the chain
    // using same action
    if(MyDataLayer.Save(myNewPerson))
    {
        var persons = MyDataLayer.GetPersons();
        persons.Add(myNewPersion);

        return View("PersonGrid", persons); 
    }

    //2. pass along the unique id of person to a different action or controller
    //yes, another database call, but probably not a big deal 
    if(MyDataLayer.Save(myNewPerson))
        return RedirecToAction("PersonGrid", ...etc pass the int as route value);

    return View("PersonSaveError", myNewPersonViewModel);
}

Now, what I'm sensing is that you want person on yet another page after PersonSaveSuccess or something else. In that case, you probably want to use TempData[""] which is a single serving session and only saves state from one request to another or manage the traditional Session[""] yourself somehow.

What is confusing to me is you're probably going to the db to get all your persons anyway. If you save a person it should be in your persons collection in the next call to your GetPersons(). If you're not using Ajax, than what state are you trying to persist?

Upvotes: 0

Srikar Doddi
Srikar Doddi

Reputation: 15599

ASP.NET MVC offers a cleaner way of working with session storage using model binding. You can write a custom model binder that can supply instances from session to your action methods. Look it up.

Upvotes: 0

Eric
Eric

Reputation: 3344

What about user session? There are plenty of valid use cases to store things in session. And what about a distributed caching system like memcached? You also seem to leave out the query string - which is an excellent state saver (?page=2). To me those seem like other desirable methods to save state across requests...?

Upvotes: 1

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