State Management :: Dynamically Loaded Controls In Init But Viewstate Not Persisting
Jan 20, 2011
I read this article first to try to solve this issue, but I am already loading the controls in the Init phase of the page, yet viewstate is not persisting. Any ideas as to why? (Of note is that this is for a custom module in DNN and I do have some AJAX update panels on the page, though this section is not within an update panel, for what it's worth.)
As an overview of what I've got:
1. LoadControl.ascx - based on reading query string parameters, determines whether to load the master or the detail .ascx.
2. Master.ascx
3. Detail.ascx
In my master control I dynamically load either a master or detail sub-control in the page_Init. The detail page has a treeview control and then uses a multi-view control to display the panel associated with the depth of the node selected on the tree. On the panel being displayed I have a cascading ddl within a detailsview control which initiates a postback to select the child ddl based on the parent ddl selection. However, when the page refreshes after the postback, both ddls have resorted to their default selection.
What is interesting however, and I just realized this as I am typing, is that the Treeview is populated when the page comes back from the postback, so that is only possible if viewstate is being persisted right? (See the page_load code and you'll see that Call PopulateRootLevel(intTreeUserID) which populates the treeview, is not called on postbacks....hmmm.
Any ideas as to why the treeview maintains viewstate but not my ddls???? But though the tree is populated, I do have to explicitly select the node again and set the panel that the detailsview control is on to visible again too....
Here is the dynamically loaded control code:
[Code]....
And in the Detail.ascx page load I've got:
[Code]....
[Code]....
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Jan 14, 2011
I have a page that loads a usercontrol dynamically. Depended on the user's actions, this control may be unloaded in Page_PreRender and a different control may be loaded instead. I am attempting to use the solution outlined by Mark DotNet Evans in this post:
http://forums.asp.net/p/1491790/3814320.aspx
This all works great, except if the user clicks the refresh button in the browser just after the change of usercontrol. Then, I get an error
Failed to load viewstate. The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request. ...
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Failed to load viewstate. The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request.Now i also load controls dynamically and use postbacks and things in the admin area of the site...and that works fine, however my front end just keeps failing? See the code behing below:
[Code]....
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May 23, 2010
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Feb 16, 2011
I am having issues with my dynamically loaded control's events.Here is how I am loading the control:
protected void Page_Load(object sender, EventArgs e)
{
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The control loads perfectly, I have tested it with a basic button and the postback fires as expected. However, I am getting weird results with CheckBoxes.
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Jan 11, 2011
I have problem getting values from viewstate in GetTopThemes.
<asp:ObjectDataSource
ID="sourceGetTopThemes"
runat="server"
TypeName="DBConnection"
SelectMethod="GetTopThemes"
EnableViewState="true"></asp:ObjectDataSource>
[Code]....
}
[Code]....
when the page is not Posted back, I saved all values in the viewstate.
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Jan 2, 2011
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[Code]....
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Apr 30, 2010
I have been getting this error a lot lately with some of my users, and I had a couple of concerns with view state and I have read so many articles but I am still lost..
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Oct 12, 2010
how can DropDownList attributes be persisted accross page Postbacks?
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Feb 12, 2010
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The first time I load the user control I call its constructor with parameters. When I reload that user control on each postback I use its normal constructor.
My problem is I the values I've stored on ViewState has become null on successive postback.
Update:
This is a piece of my user control:
public class MyUserControl : System.Web.UI.UserControl
{
private int PKId
{
get { return ViewState["pkId"] as int; }
set { ViewState["pkId"] = value; }
}
public MyUserControl(int pkId)
{
this.PKId = pkId;
}
...
}
I'm following this article to load controls dynamically: http://msdn.microsoft.com/en-us/magazine/cc748662.aspx#id0070065.
Second Update:
I also set the same control ID when I load the user control at first time and on each reaload.
Maybe I can use another method to store these values like input hidden fields or Cache. I've choosen ViewState because I don't want to overload server with Session values for each user.
Third update:
I load the controls with this code:
System.Web.UI.UserControl baseControl = LoadControl(ucUrl) as System.Web.UI.UserControl;
if (baseControl != null)
{
baseControl.ID = "DestinationUserControl";
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}
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DynamicControls.CreateDestination ud = this.LoadControl(TrackedUserControl) as DynamicControls.CreateDestination;
if (ud != null)
{
ud.ID = "DestinationUserControl";
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Dec 20, 2010
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Oct 15, 2010
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However, despite creating the controls after the ViewState has been applied (technically), the controls still somehow retain the pre-postback's information. IE: if I have options 2 and 4 selected and I choose "New", which should show the options without being selected, they remain selected no matter what. And this is true despite changing their values in the PreLoad state. From my understanding, creating a control in this fashion and at that point in the page lifecycle should override any values the ViewState might have had for those controls. I have also tried to disable the parent's control viewstate (Table.EnableViewState = false) again, to no avail.
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I have a page with several panels which are enabled or disabled depending from which page user were redirected to this particular page (based on UrlReferrer). Everything works perfectly until a user adds this page to favorites in IE8 (not sure about other browsers at this point), and then returns to that favorite in the future. It contains the previous data and not the data from the current page . When I click F5 it works again becase page is reloaded from the server and not from IE cache. How can I avoid this issue? Is there any way to force page reload only once! I tried also to put some code into "If Not IsPostBack", but it still does not work.
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I have been spending a better part of a week trying to track down why I am not able to clear all session variables in a web app (vs 2010, vb.net). What I have tracked it down to is that when I remove or abandon sessions that my html pages or codebehind access, it works, but for some reason in any of my class files where I use "Public Shared strConnection as String = HttpContext.Current.Session("strConnection").ToString" to access a session variable, it finds the old one and not the current one. I have to wait for it to time out, go in again, and it will find the new one.
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May 20, 2010
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Apr 19, 2010
I have a code like this in the Me.LoadComplete event.
[Code]....
Now I would like to set this viewstate("data") = nothing on a certain button click in a user control (.ascx) in this page but it doesnt clear the viewstate. What am I doing wrong? In the onClick even of the button in the .ascx I write Me.viewstate("data") = Nothing
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Jul 22, 2010
I want to use textbox value after I visit from current to other page then again to current page using viewstate but value should be the one when I was current page last time.
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May 3, 2010
I am creating a simple string of values that get added to a label after a post back. I am setting the values thorugh ViewState. However, my appended values do not get updated until AFTER the 2nd postback. Example:
On Page_Load the label displays a "0";
If I enter a "1" in the text box and click the button the label still displays a "0";
If I click the button again (the 2nd postback) then my label correctly displays "0,1"; This works for whatever value I enter after. i.e. "0,1,35,hello world", etc.
What I am I missing? Code Below.
.ascx - I left out inherits and codebehind
[Code]....
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Dec 22, 2010
have some viewstate value in my opener window ,when i close the popup i want to set new value in the opener viewstate.
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