Re: User control remember state across pages without session

So, no, a user control cannot maintain state across pages without using the
session.

Its a shame Microsoft don't extend viewstate beyond a single page because it
would be very useful.

--
McGeeky
http://mcgeeky.blogspot.com


"Kevin Spencer" <kevin@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:e8eB4ml1FHA.2212@xxxxxxxxxxxxxxxxxxxxxxx
> HTTP is stateless. An HTTP Request is received by the web server. It hands
> it off the the ASP.Net application. The application identifies the handler
> for that Request (a Page class). The Page class is instantiated and
handles
> the Request. It sends a Response to the client. Then it goes out of scope,
> off into NothingLand. The next Request comes for a Page. The same thing
> happens again.
>
> Now, as HTTP is stateless, ASP.Net includes some tricks for persisting
state
> across Page Requests. One is the PostBack. When the PostBack is received,
it
> contains the values in the Page, which are used to re-build the Page class
> on the server in the state it was on the client. Without it, the Page form
> would be completely empty of values, as HTTP is stateless. Another is
> ViewState. ViewState uses a hidden form field which is inserted into the
> Page when the Response is sent to the browser. It contains the current
state
> of all the form elements in the Page. When the Page Posts back, the
> ViewState is read, and the new Page instance is re-populated with the
saved
> state of the Page coming from the POST Request.
>
> Note that this enables ONE PAGE class to remember the state IT was in
prior
> to a PostBack. So, how do you persist data across multiple pages? After
all,
> HTTP IS STATELESS (I'm going to keep repeating this so that you will get
it
> drummed into your head - it is VERY important). Well, HTML has a mechanism
> for remembering a few things. It's called Cookies. So, when the first
> Request for a Page comes from any client, the Session Collection has a new
> member added to it, with a unique ID, a Guid, that identifies the client
> that sent the Request. This Guid is sent back to the client in the
> Response.Cookies collection, as a Session Cookie (it is not saved on the
> client, except during the current Session). Every time the browser makes a
> Request, it sends its Cookies in the Request header. The server reads the
> Session Cookie, and uses the Session object for that client during that
> Request/Response.
>
> So, are there any other ways to save the state of a User Control across
> multiple page requests? Sure, but they all involve one thing: The client
> must be uniquely identified on the server, so that the Page handling the
> Request, which remembers nothing about any previous Requests (because HTTP
> IS STATELESS), can identify what client data to fetch for that Page. How
to
> do that? Well, a Cookie comes to mind. You could create a Guid on the
> server, and pass it to the client in the Response.Cookies Collection, and
> read it every time a new Request comes back. You would have to store both
> the Cookie Guid, and the User Control data somewhere. Now, you obviously
> don't want to store it in memory, or you would probably use Session. You
> could store it in a database, though, for example. Of course, as HTTP IS
> STATELESS, and the server has no way to know when the client user has lost
> interest and navigated somewhere else, you would have to include some sort
> of Timeout process to remove the data from the database after a specified
> interval with no Requests.
>
> This is, of course, how Session works. So you don't have to.
>
> --
> HTH,
>
> Kevin Spencer
> Microsoft MVP
> .Net Developer
> Ambiguity has a certain quality to it.
>
> "McGeeky" <anon@xxxxxxxx> wrote in message
> news:enTSVBl1FHA.460@xxxxxxxxxxxxxxxxxxxxxxx
> >I should clarify:
> >
> > I thought that there would be some **automatic** way for a user
control's
> > viewstate to persist between pages without having to use the session.
> >
> > Thanks
> >
> > --
> > McGeeky
> > http://mcgeeky.blogspot.com
> >
> >
> > "McGeeky" <anon@xxxxxxxx> wrote in message
> > news:O3dmK%23k1FHA.3756@xxxxxxxxxxxxxxxxxxxxxxx
> >> My preference is that all state should be passed to each page as URL
> >> parameters to make testing and problem determination much easier.
> >>
> >> I thought that there would be some way for a user control's viewstate
to
> >> persist between pages without having to use the session.
> >>
> >> --
> >> McGeeky
> >> http://mcgeeky.blogspot.com
> >>
> >>
> >> "KMA" <kma@xxxxxxxx> wrote in message
> >> news:djauun$ikg$1@xxxxxxxxxxxxxxxxxxxx
> >>> Well, the control state isn't "global", is it. It depends on the
client,
> >>> or
> >>> session of that client to be precise. What's your objection to using
> >>> session
> >>> state to store the state of the session?
> >>>
> >>>
> >>> "McGeeky" <anon@xxxxxxxx> wrote in message
> >>> news:OzkY91k1FHA.1256@xxxxxxxxxxxxxxxxxxxxxxx
> >>>> No. It could be different for each client
> >>>>
> >>>> --
> >>>> McGeeky
> >>>> http://mcgeeky.blogspot.com
> >>>>
> >>>>
> >>>> "KMA" <kma@xxxxxxxx> wrote in message
> >>> news:djatq6$igr$1@xxxxxxxxxxxxxxxxxxxx
> >>>> > should the state of the UC be the same for all clients?
> >>>> >
> >>>> > "McGeeky" <anon@xxxxxxxx> wrote in message
> >>>> > news:uhVVbRk1FHA.3564@xxxxxxxxxxxxxxxxxxxxxxx
> >>>> >> Is there a way to get a user control to remember its state across
> >>> pages?
> >>>> >> I
> >>>> >> have a standard page layout I use with a header and footer as user
> >>>> > controls.
> >>>> >> Each page uses the same layout by means of copy paste (I hear this
> >>>> >> will
> >>>> >> improve in ASP.Net 2 via master pages).
> >>>> >>
> >>>> >> When I navigate from one page to the next the header and footer
user
> >>>> >> controls lose their state because they are effectively different
> >>>> >> instances
> >>>> >> of the user control.
> >>>> >>
> >>>> >> Is there any way I can make the state of the user control exist
> >>>> >> between
> >>>> >> pages?
> >>>> >>
> >>>> >> Preferably without the use of hand coding the storing of data in
the
> >>>> > session
> >>>> >> or passing parameters to the user control on each page that
includes
> >>> it.
> >>>> > Is
> >>>> >> there a way of making the user control state "global"?
> >>>> >>
> >>>> >> Thanks!
> >>>> >>
> >>>> >> --
> >>>> >> McGeeky
> >>>> >> http://mcgeeky.blogspot.com
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >
> >>>> >
> >>>>
> >>>>
> >>>
> >>>
> >>
> >>
> >
> >
>
>


.

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