Does viewstate expire?

Question

Let\'s say you have a aspx page that does not rely on session, but does rely on viewstate for persistance between postbacks.

If a user is accessing this page, and l

Answer 1

The ViewState will persist from POST to POST. It's actually stored inside a hidden field on your form so that it gets POSTed back to your server all the time.

As long as you aren't relying on the Session you shouldn't have any problems rebuilding page state. It's easy to test your Page's state code if you want though: just set your session to expire after 60 seconds in your web.config then load your page, wait a little more than a minute (surf over to Stack Overflow and answer some questions) and then click a button on your page.

Answer 2

The short answer is: no.

The longer answer is: it depends on implementation of ViewState storage. You can provide custom implementation of ViewState which could expire after given amount of time. For example, you could store ViewState in database or on disk and send only some reference to the stored value in a hidden field. Then you can use batch processing to remove outdated ViewState data or perform expiration upon request.

Answer 3

Yes, ViewState expires in certain conditions. For example when you are using iframe:s, or when you are upkeeping "live" connection to the server with regular postbacks. Then you might want to investigate this option: <sessionPageState historySize="9"/>, which actually hard-codes how many "postback results" are stored in the Session (if SessionPageStatePerster is used). Each postback stores it's ViewState to the end of the Queue in Session["__VIEWSTATEQUEUE"], and deletes ViewStates that are "too old". And how do you think SessionPageStatePerster decides which ViewStates are too old.. by configuring some arbitrary historySize-constant in web.config.. Omg! It too me forever to find this problem... My hatred toward asp.net programming is undescribable now.. grrr...

Answer 4

By default, Viewstate is included with the html content as a hidden input. That means it won't expire, but that everything in viewstate must be uploaded from the user's browser. Since that's typically the slowest part of the connection in a public site, putting a lot of stuff in viewstate can quickly make your site seem very slow.

Answer 5

No ViewState is kept as part of the PostBack process. You can, however, override the Page class's SavePageStateToPersistenceMedium() and LoadPageStateFromPersistenceMedium(), to implement that behavior if desired. For more information read Understanding the ASP.NET ViewState.

Note that Page ViewState is stored in the Session so if your Session expires, the ViewState will be lost. I wouldn't say this is ViewState expiring, but yes, it will be destroyed after Session timeout.

Answer 6

Sorry to relive this old thread, but new information is available now:

Yes, ViewStates expire. I come from 19 hours researching about a problem of ViewStates losing its values between long time interval postbacks. It took me a while reading MSDN documents and Stackoverflow answers saying it was basically impossible to happen unless a custom ViewState storage implementation was employed, which, now I know, it's not true.

My problem was taking place in a SharePoint 2013 environment. The service known as Distributed Cache (a.k.a. AppFabric) does the caching of the ViewState and has a Time to Live associated to it. You can find more information here: http://blogs.msdn.com/b/besidethepoint/archive/2013/03/27/appfabric-caching-and-sharepoint-1.aspx

The interesting bit of information can be found in this phrase: "To improve page performance, beginning in SharePoint 2013 SharePoint caches ViewState data server-side rather than transferring it back and forth to clients."

I hope this information helps somebody so desperate as I was 19 hours ago.