well what i want to find out is how can i figure out if some change occurd in page when postback , i mean when the first state of the page hahe any changes after postback . I thought maybe somehow to compare viewstaes but i can not find out how can i do that.
View 13 Replies
In my ASP.NET page I have to dynamically choose and load a custom control, depending on the selected value in a dropdownlist.However I encountered the following problem: When the parameters of the dynamically loaded control are changed, and then the selection in the dropdownlist is changed( thus forcing me to load a different dynamic control the next time the page reloads ), I end up with a "Cannot load ViewState" exception.I assume that this happens because the ViewState is trying to restore the parameters of the old control and it doesn't find it. So , is there any way to stop the viewstate from attempting to restore the state of the non-existig control?
View 2 Repliesi have a textbox and a button.when the page loads, the textbox text read "hello"now when a user changes the text and then presses the button which causes a postback, how can i check if the user changed the value of the textbox or not?
View 2 RepliesI'm not sure whether or not this is the correct forum...I have been asked to develop a webpage with a very simple table. 10 columns, 10 rows. Each cell will have a dropdownlist. Several people will have this page up at any given time and they will all make changes as needed. I am planning on using a SQL Server
2008 database to keep track of the entries.I need the page to verify the data it contains against the data in the database every 5 seconds or so. If they are different, either the page can refresh or (if possible) the dropdownlist can just change to the correct value.
I have done outbound rule for anchor(A) tag. after clicking an anchor tag the page gets redirected to the specified page with rewritten url. but when i change value from dropdown list or click on any button on that page, the page url gets changed to old url(the original url for which we did new url.) so i dont want that url to be changed. how can i do that.
View 1 RepliesI have a grid with rows of data, but the page will fail have several postback. I check it with fiddler and find that view state expands 2-3 times after each post back.
The thing I did to trigger the post back is searching and sorting. I am not sure how it happens.
I want to be able to find the old value of a asp.net control (textbox, checkbox etc) without relying on events (e.g. OnTextChange event). Something like "someTextboxControl.OldText" would be perfect! I imagine that it is stored in the viewstate and need to somehow get at it via a custom control.
View 2 RepliesI need to databind the gridview inside the Ajax UpdatePanel each time user types letter inside my TextBox control. How to override the TextChange event to force it do postback for me?
<script type="text/javascript">
function ace1_itemSelected(sender, e) {
var hdCustID = $get('<%= hdCustID.ClientID %>');
hdCustID.value = e.get_value();
</script>
[code]...
I'm having trouble with a simple radio set of two radio buttons (I don't want to use a RadioButtonList [RBL] because RBL doesn't allow child controls, and in my case, if you select one option, I want to enable a textbox next to the button; yes you could hack this with jQuery to move the textbox, but that's dirty!). I would check one, submit the form (either explicitly or through AutoPostBack), and the CheckedChanged event would never fire. When the page was reloaded, both buttons would be unchecked, regardless of their initial state on non-postback load or the state before form submission.
form id="form1" runat="server" enableviewstate="true">
<div>
<asp:RadioButton ID="foo" Text="foo" runat="server" AutoPostBack="true" OnCheckedChanged="rbChanged" Checked="true" GroupName="foobar" EnableViewState="true" />
<asp:RadioButton ID="bar" Text="bar" runat="server" AutoPostBack="true" GroupName="foobar"
OnCheckedChanged="rbChanged" Checked="false" EnableViewState="true" />
[code]...
Is there a reliable method for viewing the size of the viewstate on any given postback?
View 3 RepliesI 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]....
Is it necessary to reload the viewstate of usercontrols during postback? I want to know in which case viewstate is set by default.
View 2 RepliesI've got a weird problem with a NullReferenceException on a high traffic website my company hosts. The exceptions are logged with full stack-traces but I am unable to reproduce it.The exception occurs a couple of times a day, for different users, and it's a NullReferenceException thrown in the code block below:
protected void Page_Load(object sender, EventArgs e)
{
...
if (!Page.IsPostBack)
{
...
this.ViewState[StaticClass.StaticStringProperty] = StaticClass.StaticIntProperty; // this is the line the exception occurs on
...
}
}
The only place I can figure that a NullReferenceException would be thrown is if ViewState is NULL, but I've never known that and can't find any reason why this would be the case in a Page_Load that isn't a postback.StaticStringProperty and StaticIntProperty are both initialised, static properties of StaticClass.
StaticStringProperty is defined as:
public const string StaticStringProperty = "IdFromClient";
Does anyone know how this could happen, or any other reason why a NullReferenceException would be thrown on the above line?
EDIT.As requested, the full stack-trace for the error is as follows. Line 54 is the line I've highlighted above.
at MyCompany.MyApplication.Appliance.Page_Load(Object sender, EventArgs e) in C:Documents and SettingsshellamaMy DocumentsMyApplicationAppliance.aspx.cs:line 54
at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)[code]....
<asp:DropDownList ID="cboItemsPerPage" runat="server" CssClass="standardComboBox" AutoPostBack="true" EnableViewState="true" OnSelectedIndexChanged="cboItemsPerPage_SelectedIndexChanged">
<asp:ListItem Value="1" Text="1" />
[URL]Initially if I make a selection it will automatically post back and firecboItemsPerPage_SelectedIndexChanged. If I then post back by clicking one of the other buttons on the page, cboItemsPerPage_SelectedIndexChanged will continue to fire, despite the fact that the value has not been changed.I want it to be postback only when selected index is changed, not in every postback
I've created a Web User Control that is placed on the page at design time. It's purpose is to pop up with a grid of items the user is to choose from. So I've got a gridview on it. And this code in the usercontrol:
Public Property DataTable() As Data.DataTable
Get
If Not IsNothing(ViewState("_SelectGridDataTable")) Then
Return ViewState("_SelectGridDataTable")
Else
Return Nothing
End If
End Get
Set(ByVal value As Data.DataTable)
ViewState("_SelectGridDataTable") = value
End Set
End Property
So when the user clicks on a button on the page, I put this in the code on the page:
SelectGrid2.DataTable = GetContacts().Tables(0)
SelectGrid2.Show()
And this works fine. The grid pops up (using jQuery) and the grid is shown. The problem is, that when the user clicks the "OK" button on the UserControl, the ViewState("_SelectGridDataTable") is always nothing. And I don't get it, since it's in the viewstate.. ?!? So does viewstate here not REALLY mean viewstate?
I am looking for an event firing before a DropdownList auto-postback to save Listbox items (populated with JS) in the ViewState.I tried the OnSelectedIndexChanged event but it's fired too late.
View 5 RepliesI'm reading about the UpdatePanel and how it interacts with controls inside & outside of it.
My understanding is that the usual ASP.Net pipeline takes place when posting from within an UpdatePanel-- Page load etc all fire off as normal-- except when the prerendering stage is reached. In that case the ScriptManager does a final check and only renders those controls within the UpdatePanel and skips the rest. That's my understanding at least.
Sounds good, but for argument's sake let's say I have a TextBox located outside an UpdatePanel. If a postback occurs from within that panel, the TextBox's properties can still be set in the page load method, but those changes will not take effect. (normally; it is possible to postback the entire page from an UpdatePanel)
Is that correct? What happens to that TextBox's ViewState in this instance? Is it updated based on what happened to it in the page load method or is that modification tossed out because it wasn't in the UpdatePanel?
I'm getting some strange behaviour with viewstate being lost on postback for a .net application using Sitecore. I'm assuming it might be some config variable somewhere but I'm new to Sitecore and don't really know where to start looking.
UPDATE: Sitecore has now gotten back to us with an answer. We had recently added the dtSearch module, and AutomaticDataBind was set to true in the dtSearch.config which overrides the setting in the web config. We've now removed it and it works fine again.
I've made a mini test if that might help. It's two usercontrols on one page, both with a repeater. When updating the viewstate gets lost so even if I'm binding the updated repeater again the data for the other one will be lost.
Usercontrol 1:
<asp:Repeater runat="server" ID="Repeater1" OnItemDataBound="Repeater1_ItemBind">
<ItemTemplate>
<li>
<asp:Literal runat="server" ID="Literal1"></asp:Literal>[code]....
what might be going on? Let me know if I need to provide any more information. The most annoying thing is that it was working last week but I have no idea what has changed!
The values are stored in viewstate fr the postback... Does everysubsequent post back increase the viewstate size?
View 1 RepliesIn ASP .NET 2.0, I've created a user control which is meant to work as a dropdown or popup by using an <input type="button" id="btnTogglePopup" runat="server" style="display:inline"... /> and <div id="divPopup" runat="server" style="display:none" ... /> the rest of the controls are contained inside this div, and they do mantain their values between posts, etc. This button 'runs at server' but it's not intended to post back or submit.It just toggles the popup (div) visible/hidden using Javascript client code by setting the div's style display property to "none" or "block" The problem I'm having is that when a page containing this control posts back, the state visible/hidden of the div is not maintained. If the user had the popup open, after the postback, it will display closed.I've read a bunch by now about ViewState & ControlState, and have the save and load contol state methods working, but when I step thru them they load old values (setting the popup to hidden all the time),and the popup doesn't work! I've come to think that b/c when the button is clicked,the visible state of the div is changed in client code w/o a postback, maybe I have to maintain this state info in a hidden fiel or something like that?At the same time I don't want to have a hidden field if it's unnecessary,and I may just doing something wrong.
View 2 RepliesI have a gridview control that extends the default gridview. I have added an attribute called "hiddenSelectedValues" to to the gridview during the "PreRender" event and I have a private variable that points to the value of that attribute.
I have some javascript code that modifies the value of this attribute based on the user checking or unchecking checkboxes in the grid. I have confirmed that the javascript is indeed modifying the value of the "hiddenSelectedValues" attribute by using Firebug to see the change as it happens.
However, once a postback occurs, the grid looses the updated value of this attribute and I am unable to reference get the updated value on the server side.
How do I keep the value of an attribute changed by javascript on postback?
I have a bit of javascript that presents a modal to the user with the rest of the page "grayed out." Pretty common these days. The modal allows you to specify a URL which then uses AJAX to serve and display. What I need is that when the control posts back, it posts back to the parent page, not the modal page. To attempt this, I used javascript to alter the target of the modal page's form element to the parent page's URL. When I try this I get the following error:
Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.
This is done locally and as of now, the app will never be on a cluster. I think this has to do with the validation process and .NET doesn't like that I've changed the target. Anyone know a way around this? I really need this to work how I described.
When we disabled the viewstate in gridview its lose value but this case not true with Textbox control why?
View 1 RepliesI have "n" <tables></tables> on my page and each <table> has One(1) <asp:CheckBox.. Enable ='true"/> and "x" <asp:TextBox Enabled="false"..>. Each Table looks as follows
[Code]....
When I click checkbox, it calls javascript function and enables textboxes (I have added onclick attribute to checkbox). Page also has <asp:Button ...Text="Submit"/> whcih actually grabs the data from the textboxes on the page and send it to the databse. Here is the Onclick event of the <asp"button../>
[Code]....
If the exception is thrown , textBoxes are not reset but on postback textboxes appear as disabled (values are not reset)
So here is what happening on postback when exception is thrown
1) Values are not reset (that is what want)
2) Texboxes appear as Disabled (that is what I don't want on exception, REMEMBER I enable textBoxes using client side script)
How can I keep the textboxes enabled = "true"
I've build a class like this:
[code]....
The values of this class are set at postback by clicking a radiobutton list. Problem however is I don't know how to save this values across multiple postbacks. I thought of using viewstate but I'm not quite sure how to do it with this class.
Maybe I'm missing some important thing here.
Hope someone can point me in the right direction.
