Why the label text not saved in view state?

Question

0.00/5 (No votes)

See more:

Hi, guys:
When I use Aps.net Ajax UpdatePanel control, it seems the newly setted label text value (either on the UpdatePane.Load event or Page_load event) is not saved in the view state. Details below:

In my opinion, firstly I set the text property of label one value on the mark up html(for example "<asp:label runat="server" id="label1" text="LabelText"/>). And then in the code behind .cs file, in the event like page_load, I set the label1.text another value(label1.text="newvalue"). When the page render to the browser, the label text value should update to the newvalue.

Above case works well, but when I add one UpdatePanel control and one gridview(in the UpdatePanel template of course) which holds the paging data table, each time when I select different page, and the both Page_load and UpdatePanel load raised, but in both events, I set the label.text new string value, the rendered page only display the string set first time, no update at all.

I have two questions:
1. Asp.net Ajax control is partial post back, why the page_load event raised when I using UpdataPanel control post back.
2. What inside the view state storage? It seems the new label.text value not saved in view state.

I read "the page life cycle and view state" from http://msdn.microsoft.com/en-us/library/ms972976.aspx#viewstate_topic3; and the sequence of events is "Instantation page ---> Load view state --->Load Page --->Load UpdateLabel--->Save view state--->Render to client"

Can I understand if I use Asp.net Ajax control, the sequence events changed? Or the view state is not saved any more?

Posted 27-Oct-11 3:26am

penn dai

Add a Solution

Comments

Muralikrishna8811 27-Oct-11 9:31am

If that label within update panel then only it updates otherwise not.

In any case page_load event is must and should that is the Microsoft Architecture

make sure your label must be in update panel

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Muralikrishna8811 · Answer 1 · 2011-10-27T03:46:00

Hi,

let me tell you simple example

I've three Textbox controls and one Button in my page textbox1,textbox2,textbox3

And I place one Textbox which id is textbox1 and one Button in update panel

Now I write code in page load like

C#

//under pageload
textbox1.Text=System.Date.Now.Tostring();
textbox2.Text=System.Date.Now.Tostring();
textbox3.Text=System.Date.Now.Tostring();

And

same code in Button click event also

Then when user clicks button the client side javascript which is referred in ScriptManager sends xmlhttp request to server with some information which contains ViewState,Ids of controls which are placed in update panel
and control information which control raises the event

in this example
textbox1 and value of textbox1 to server with some other information

In server side
All code which is pageload and buttonclick events runs

finally In the Response
server only places information based on request

In this example value of textbox1 only returns to browser

In client side the javascript takecare of returned information to place particular control value.

In this example the only textbox1 updated to current time

I hope you understood what I mean

All the Best