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19 Items, 1 Pages 1 |< << Go >> >|

	troy23
	Asp.Net User

Viewstate Expert Needed

1/2/2004 11:50:12 PM

0/0

Viewstate is being lost between calls. I thought it would be a global value. Here is the scenario:

Container form contains a button event to send a path string to a user control as follows

Private Sub btnDept_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDept.Click
Me.ucAdminComboUpdate.xml_path = "../xml/Department.xml"

End Sub

The user control accepts the string and sets the viewstate in a property procedure. However , when the code returns to the user control the viewstate is lost and the 'BindData' procedure cannot load the file as it has no path from the viewstate.

User control

Public Property xml_path() As String
Get
Return viewstate("xml_path")
End Get
Set(ByVal Value As String)
viewstate("xml_path") = Value
End Set
End Property

Private Sub BindData()

Dim doc As New XmlDocument

' Response.Write(xml_path)

If Me.IsPostBack = True Then

doc.Load(Server.MapPath(xml_path))

End If
End Sub

Private Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.PreRender

BindData()

End Sub

	NetProfit
	Asp.Net User

Re: Viewstate Expert Needed

1/3/2004 12:33:21 AM

0/0

Are you creating this user control on your page declaratively (at design time), or are you loading it dynamically at runtime?

I'm guessing that you are loading it dynamically at runtime. If that's the case, it should be loaded before or during Page_Load so that its viewstate can be restored by the page once it is added to the control tree.

If you're looking for more help, please post the code from your .aspx page where you load the control.

Jamie Kindred, CGA, MCSD
Senior Solutions Architect
TSi Auto Solutions

	master4eva
	Asp.Net User

Re: Viewstate Expert Needed

1/3/2004 7:53:32 AM

0/0

For view state to be restored correctly as well (if you are injecting server controls dynamically which I also suspect) is to have a static ID to the new server control.

-- Justin Lovell

	troy23
	Asp.Net User

Re: Viewstate Expert Needed

1/3/2004 3:14:17 PM

0/0

Thanks for replying. Below is the declaration of the user control within the html and code behind. I am unsure how it can be loaded during the page load event.



<%@ Register TagPrefix="uc1" TagName="AdminComboUpdates" Src="AdminComboUpdates.ascx" %>


<%@ Page Language="vb" AutoEventWireup="false" Codebehind="admin.aspx.vb" Inherits="pims.admin"%>


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">


<HTML>


	<HEAD>


		<title>admin</title>


		<meta name="GENERATOR" content="Microsoft Visual Studio .NET 7.1">


		<meta name="CODE_LANGUAGE" content="Visual Basic .NET 7.1">


		<meta name="vs_defaultClientScript" content="JavaScript">


		<meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">


	</HEAD>


	<body MS_POSITIONING="flowLayout">


		<form id="Form1" method="post" runat="server">


			<uc1:AdminComboUpdates id="AdminComboUpdates1" runat="server"></uc1:AdminComboUpdates>


			<table cellSpacing="0" cellPadding="0" width="100" border="2" style="WIDTH: 600px; HEIGHT: 14px">


				<tr>


					<td style="HEIGHT: 38px"></td>


					<td style="HEIGHT: 38px"></td>


					<td style="WIDTH: 101px; HEIGHT: 38px"></td>


					<td style="WIDTH: 103px; HEIGHT: 38px"><asp:Label id="lblDept" runat="server" Width="86px" Height="21px">Department</asp:Label></td>


					<td style="WIDTH: 2px; HEIGHT: 38px"><asp:Button id="btnDept" runat="server" Width="30px" Height="25px"></asp:Button></td>


					<td style="WIDTH: 45px; HEIGHT: 38px"></td>


					<td style="HEIGHT: 38px"></td>


					<td style="HEIGHT: 38px"></td>


					<td style="HEIGHT: 38px"></td>


				</tr>


				<tr>


					<td style="HEIGHT: 38px"></td>


					<td style="HEIGHT: 38px"></td>


					<td style="WIDTH: 101px; HEIGHT: 38px"></td>


					<td style="WIDTH: 103px; HEIGHT: 38px"><asp:Label id="lblEthnic" runat="server" Width="125px" Height="21px">Ethnic Group</asp:Label></td>


					<td style="WIDTH: 2px; HEIGHT: 38px"><asp:Button id="btnEthnic" runat="server" Width="30px" Height="25px"></asp:Button></td>


					<td style="WIDTH: 45px; HEIGHT: 38px"></td>


					<td style="HEIGHT: 38px"></td>


					<td style="HEIGHT: 38px"></td>


					<td style="HEIGHT: 38px"></td>


				</tr>


			</table>


		</form>


	</body>


</HTML>








Public Class admin


    Inherits System.Web.UI.Page





    


    Protected WithEvents ucAdminComboUpdate As New pims.AdminComboUpdate

Edit by moderator - NetProfit: Added < code></ code> tags.

	troy23
	Asp.Net User

Re: Viewstate Expert Needed

1/3/2004 3:37:30 PM

0/0

Thanks for your reply also. Could you pls explain further with any code samples as I am a newbie at this and my books don't seem to cover the topic in much depth. Thank you.

	master4eva
	Asp.Net User

Re: Viewstate Expert Needed

1/3/2004 6:02:39 PM

0/0

My suggestion and the other poster's suggestion is void in your case because the controls do have a static ID. I do see the problem in your code. With this code-behind line:



Protected WithEvents ucAdminComboUpdate As New pims.AdminComboUpdate

Change it to this:



Protected WithEvents ucAdminComboUpdate

-- Justin Lovell

	troy23
	Asp.Net User

Re: Viewstate Expert Needed

1/4/2004 10:06:58 AM

0/0

Thanks for the reply. I tried your suggestion, but I get an error saying "with events must have an AS clause".

	master4eva
	Asp.Net User

Re: Viewstate Expert Needed

1/4/2004 5:52:19 PM

0/0

/me Hit self on head.

Sorry for that, my head was not thinking when I wrote that post (and partially, I am a C# guy) :) . The line is supposed to look like:



Protected WithEvents ucAdminComboUpdate As pims.AdminComboUpdate

-- Justin Lovell

	NetProfit
	Asp.Net User

Re: Viewstate Expert Needed

1/4/2004 5:57:26 PM

0/0

Try:



    Protected WithEvents ucAdminComboUpdate As pims.AdminComboUpdate

or:



    Protected ucAdminComboUpdate As pims.AdminComboUpdate

Jamie Kindred, CGA, MCSD
Senior Solutions Architect
TSi Auto Solutions

	troy23
	Asp.Net User

Re: Viewstate Expert Needed

1/4/2004 6:08:53 PM

0/0

Thanks again...having tried the line of code in both your and the next posting suggestion I get an error of "Object reference not set to an instance of an object" at the line.

Me.ucAdminComboUpdate.xml_path = "../xml/Department.xml"

	NetProfit
	Asp.Net User

Re: Viewstate Expert Needed

1/4/2004 6:20:14 PM

0/0

Where did you put this line?

Make sure it is outside of any sub procedure.

Make sure the variable name is identical to the ID in your server tag for your user control.

Jamie Kindred, CGA, MCSD
Senior Solutions Architect
TSi Auto Solutions

	troy23
	Asp.Net User

Re: Viewstate Expert Needed

1/4/2004 6:39:37 PM

0/0

That's great it works now. Seems like I had not used the server ID of the user control in the declaration. I've noticed in some cases people tend to use the Load command for loading user conrols...is there a particular reason for this and would it make life easier for what I am doing? Thanks again for your help

	troy23
	Asp.Net User

Re: Viewstate Expert Needed

1/4/2004 6:41:11 PM

0/0

Thanks it's ok now. Your and the other posters suggestions worked nicely. Just needed to use the server ID of the user control in the declaration

	NetProfit
	Asp.Net User

Re: Viewstate Expert Needed

1/5/2004 1:14:31 AM

0/0

The LoadControl method is good for situations where you need to load certain user controls dynamically depending on the scenario. If this is not a requirement it is better (ie: more simplified) to create them declaritively on your form at design time.

Glad it's working ok for you now. :)

Cheers,

Jamie Kindred, CGA, MCSD
Senior Solutions Architect
TSi Auto Solutions

	tine2502
	Asp.Net User

Re: Viewstate Expert Needed

1/6/2004 11:29:15 AM

0/0

Hi,
could someone of you put a solution in c#, too? I'm having some problems with that, too, even if i load my controls in the beginnings and set them visible / unvisible. Perhaps its a problem that i have a control in another control?
Thanks!

	master4eva
	Asp.Net User

Re: Viewstate Expert Needed

1/6/2004 1:01:19 PM

0/0

This VB?



Protected WithEvents ucAdminComboUpdate As pims.AdminComboUpdate

If it is, it is in C#:



protected pims.AdminComboUpdate ucAdminComboUpdate;

-- Justin Lovell

	Alan Wardle
	Asp.Net User

Re: Viewstate Expert Needed

1/14/2004 5:07:15 PM

0/0

Hi Jamie,
I'm sorry to bother you with this, but looking at your previous posts I thought you'd probably know the answere to my problem.

I'm setting Viewstate in a control event. After posting, in the Page_Load event I find
that the ViewState does not show the correct value. If the page is posted again, the
correct value IS shown.
How do I recover the correct control event ViewState on the first Page_Load, Thanks.

As an example of problem, here's a simple example which demonstrates it

<%@ Page Language="VB" %>

<script runat="server">

Sub Page_Load
ViewState("PageLoad")+=1
lblLoad.text="Load :" & ViewState("PageLoad")
lblClick.text="Click :" & ViewState("Function")
End Sub

Sub But_Click(s as Object, e as EventArgs)
ViewState("Function")+=1
End Sub

</script>

<html>
<head><title>Bug Test</title></head>

<form runat="Server">

<asp:Label
ID="lblLoad"
runat="Server"/>
<br><br>

<asp:Label
ID="lblClick"
runat="Server"/>
<br><br>

<asp:Button
OnClick="But_Click"
Text="AddToFunctionViewState"
runat="server"/>
<br><br>

<asp:Button
id="But2"
Text="AddToPageLoadViewState"
runat="server"/>
</form>
</body>
</html>

Thanks a lot

	NetProfit
	Asp.Net User

Re: Viewstate Expert Needed

1/15/2004 3:16:50 AM

0/0

Remember that a control event, such as a button click event, fires after the page load event. We cannot change the order of these events, they are determined by the page framework. I am guessing that you are seeing this problem with ViewState("Function"). Since page_load is executing before your button click, you are indeed seeing the old value during page load. After your button click event executes, you will notice that ViewState("Function") has the new value. Try putting this line in your button click event handler after the line that updates the VeiwState:



    lblClick.text="Click :" & ViewState("Function")

If you need more control over the ViewState of this particular control, so that it is available during the page_load event, you will need to set the VeiwState variable earlier on during the page life cycle, or build your own server control that implements the IStateManager interface. The first option is limited but simple, the second option is flexible but somewhat complex.

BTW: Please enclose your code inside of < code></ code> tags to keep the formatting nice! ;)

Hope this is of some help.

Jamie Kindred, CGA, MCSD
Senior Solutions Architect
TSi Auto Solutions

	Alan Wardle
	Asp.Net User

Re: Viewstate Expert Needed

1/16/2004 1:07:17 PM

0/0

Now that I appreciate the order of events, my page goes from SQL Server record insert to
update with no problems, nice one.

19 Items, 1 Pages 1 |< << Go >> >|

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