Q: Questions about ViewState versus Session.

[Sky]

Although I've been using C# for the last month or so, and accepting out of
blind faith the ViewState, I do have some nagging questions about it... can
you help verify the following statements?

Application is across all sessions.
Session is across all pages.
ViewState is sort of like Session, but for only one page. <-- Correct
statement?

Session is stored between page requests, somewhere in mem or IIS files --
but can be rerouted to DB.
ViewState is sent to Client and returned on every post <-- Correct
statement?

If you load a DataSet.Table of 10 columns, 10 rows, and Bind it to a
DataGrid
you are sending to the Client 10x10 html cells of a table -- PLUS in the
ViewState 10x10 values encrypted. <--Correct statement?

If you load a DataSet.Table of 10 columns, 10 rows, and Bind it to a
DataGrid
but hide 7 columns you are sending to the Client 3x10 html cells of a
table -- PLUS in the ViewState 10x10 values encrypted. <--Correct statement?

Therefore, if you load a DataTable with 10 columns, 1000 rows, Bind it to a
DataGrid, but put Paging on 10 per page...
I am sending 10x10 html cells to the client -- PLUS 10x1000 cells in the
ViewState?????


If I DataBind a DataTable to a grid on page_load, I don't have to rebind it
again until I update the database, and have to repick up the new DataSet <-
Correct?


Any other comments you may have as to what it is, and "how to think of it"?

Thank you so much,
Sky

 

[Teemu Keiski]

Hi,

first off you might want to take a look at this article:

ViewState: All You Wanted To Know
http://aspalliance.com/135

Well,

-ViewState is page-specific
-By default ViewState is roundtripped to the client, but can also be stored
on custom stores like Session or database
-ViewState contains the values that aren't carried along with the request
normally, yes, helping with control persistence over postbacks (only the
values, not controls themselves)
-Yes, ViewState is kept even if control wouldn't be rendered (occasionally
hidden control can keep its state as long as it is along with the controls
collection between the subsequent requests by the same client)
-As far as I know, persisting the state (like with DataGrid) is all or
nothing. This is though a place for custom paging solution when you don't
need to bind that much records, but data store handles the paging not the
grid from all the data. E.g one page at a time is bound to the grid and
stored to ViewState (ViewState isn't for the paging in this case actually
but to keep the grid if some other controls causes a postback and grid isn't
databound on all request, as it shouldn't be)
-Yes, thanks to ViewState you need only to rebind the controls when logic
requires to.

--
Teemu Keiski
MCP, Microsoft MVP (ASP.NET), AspInsiders member
ASP.NET Forum Moderator, AspAlliance Columnist






Although I've been using C# for the last month or so, and accepting out of
blind faith the ViewState, I do have some nagging questions about it... can
you help verify the following statements?

Application is across all sessions.
Session is across all pages.
ViewState is sort of like Session, but for only one page. <-- Correct
statement?

Session is stored between page requests, somewhere in mem or IIS files --
but can be rerouted to DB.
ViewState is sent to Client and returned on every post <-- Correct
statement?

If you load a DataSet.Table of 10 columns, 10 rows, and Bind it to a
DataGrid
you are sending to the Client 10x10 html cells of a table -- PLUS in the
ViewState 10x10 values encrypted. <--Correct statement?

If you load a DataSet.Table of 10 columns, 10 rows, and Bind it to a
DataGrid
but hide 7 columns you are sending to the Client 3x10 html cells of a
table -- PLUS in the ViewState 10x10 values encrypted. <--Correct statement?

Therefore, if you load a DataTable with 10 columns, 1000 rows, Bind it to a
DataGrid, but put Paging on 10 per page...
I am sending 10x10 html cells to the client -- PLUS 10x1000 cells in the
ViewState?????


If I DataBind a DataTable to a grid on page_load, I don't have to rebind it
again until I update the database, and have to repick up the new DataSet <-
Correct?


Any other comments you may have as to what it is, and "how to think of it"?

Thank you so much,
Sky