C# - How To Avoid Persisting Data Through ViewState For A Child Control
Mar 3, 2010
I have a control (say, a DataGrid or a ComboBox) which is a child of a user control. I want to DataBind it on every request, rather than have it's state persist through ViewState. I need to leave EnableViewState=true however. This means, I think, that I need to call DataBind before TrackViewState() is called.
I read the fantastic blog post TRULY Understanding ViewState and it answers my question in 4. Initializing child controls programmatically. However, the article's solutions are less-than-ideal: create child controls dynamically (I'm not and can't -- too much existing code), use a 3rd party CodeExpressionBuilder (would much prefer this was in code-behind), and use OnPreInit (which "doesn't help you what-so-ever if you are developing a CONTROL").
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Mar 17, 2010
By default the postback of child controls will trigger update panels' update.
How can I avoid the same?
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Dec 29, 2010
I've got a master page with a section for subnavigation links on it:
<div id="sub_nav" runat="server"></div>
I programatically populate this with Hyperlinks when my main asp:Menu data is bound depending on the address of the page I'm on.
This works fine and all my correct submenu stuff shows up on each page. The problem is that when one of these pages does a postback, I lose all the links that were in my sub_nav div.
Now, I could just populate the div with links every time regardless of whether the master page load is a postback or not, but I figured there is a better way of doing this. I was thinking enabling the viewstate on the div and links inside it might persist them through postbacks, but apparently that is not how viewstate works.
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Apr 28, 2010
Maybe it's been a long day but I'm having trouble persisting a collection backed by the ASP.NET ViewState in a CompositeControl. Here's a simplified version:
public class MyControl : CompositeControl
{
public Collection<MyObject> MyObjectCollection
{
get {
return (Collection<MyObject>)ViewState["coll"] == null ?
new Collection<MyObject>()
: (Collection<MyObject>)ViewState["coll"];
}
set { ViewState["coll"] = value; }
}
}
public partial class TestPage : System.Web.UI.Page
{
protected void btn_Click(object sender, EventArgs e)
{
myControl1.MyObjectCollection.Add(new MyObject());
}
}
When the button is clicked, the event hander btn_Click executes fine, but the setter for MyObjectCollection never gets called, hence the new MyObject() never gets persisted.
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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 25, 2010
I know this is a very common problem and a quick search in google offers a lot of solutions. However I could only find one person that came across it in the same way I am and no-one answered their question.
The scenario which causes this is if the page has been left dormant for a period of time and then a button is pressed which runs some sort of command. This might be pressing the logout button or trying to submit a contact form after having walked away at some point and then returning and hitting Send.
I do not have posts or actions in my form, it looks like this: <form id="form1" runat="server">
I have also added the following line to my web.config: <pages enableEventValidation="false" iewStateEncryptionMode="Never">
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Apr 12, 2010
how can i avoid or rather not send viewstate when i post from jquery?
i try to put on the .aspx EnableViewState="false" but has no effect...
here is how iam posting my page:
var json = "{'firstname':'" + escape(firstname.val()) + "','surname':'" + surname.val() + "','day_fi':'" + day_fi.val() + "'}";
var ajaxPage = "wizard_data_process.aspx?returnId=0";
var options =
[Code]....
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Sep 21, 2010
how to make a control that can have controls nested inside it. I've made a jQuery tab browser class which uses a hidden field to remember which tab is selected and create the relevant client script to re-select it on postback...it works fine...
This is for web part development so all controls are created dynamically.
The problem is when I add a control to one of the tabs, the values set in that control disappear on postback..I understand there is a lot of information about user controls, viewstate and control state but nothing seems to give me access to those values...
I've boiled it right down to the basics and still can't get it to work unless the custom control has all its controls added in OnInit...which is bad news for me because I need to instantiate the browser, the use a 'AddTab' method to add tabs and controls to them, which occurs after the OnInit event and therefore I can't access the postback values!!
I get the feeling I'm missing something big here, I must be lol...here's is an example:
[Code]....
These controls have to be dynamically created, so I didn't see the need to make the ascx user controls..
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Dec 9, 2010
I have an application that works fine, problem rise when a page is waiting for the user response for more than 20 min and then user click a link on the form. The application response with 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.
I read a few articles regarding setting the Pages tag in web.config and set the Pages tag to the following -
[code]....
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Aug 30, 2010
I haveMaster Page -> ASPX page -> User ControlUser control page is contains all dynamic bind controls (e.g Repeater) depended on ASPX Page (Only one parameter say ItemNo)The problem is, if I bound user control on page load event with passing respective parameters then it's create to much view state (I checked source file and it's almost 1.5 MB)In other way if I put one textbox, and a command button and I pass required parameter on button click and load the control then page size is ok (I checked and it's < 500KB)
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Dec 21, 2010
Consider I have 2 controls, C and CompositeC which contains C. Both C and CompositeC have ViewState.
Now consider a third control causes a postback.
The resulting life cycle will be as follow:
CompositeC tries to restore state. To do so it needs to create the child controls, so it creates C.
When C is created it's ViewState is restored.The third control's postback event is triggered. At this time a handler calls CompositeC.RecreatedChildControls() and C is created again.Everything renders.
The problem is that C state is not restored again after step 3. RecreateChildControls method should modify the control's state so that when C is reintroduced to the CompositeC control's collection it's viewstate is automatically restored but it doesn't.
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Oct 9, 2010
Now here is the weird thing. First i am running it locally on the built in vs2008 web server.I load my control in fine, do a postback from a linkbutton, locally on my machine it all works fine, no issue.However when it goes onto my host, it falls over with the message:
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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Jan 11, 2011
I have this problem - I'm working on an ASP.NET AJAX-application on a server without .net 3.5 which means I can't use ListView (BOO!).
I decided to simply do the ugly way of making a table and giving the tbody an ID and a runat server tag, and put HtmlControls inside from the codebehind (btw - this is a usercontrol, in case it makes a difference).
This all works fine - until the page does a partial postback - and all the elements disappear, since the tag is runat server I assume it requires to be repopulated in the page load.
Is there no way to actually persist the data on partial postback? And only have the content of the control change when I say so in the back end?
I guess I could save the content in a session object upon populating the control, and just repopulate in the Page_Load with the session object - but I was hoping there was a better way to do this?
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Sep 15, 2010
I am using a form view control which has two binded textbox. Now at this level it works fine and the textboxes show the values from database. But when i insert a panel inside the form view and move these two textboxes inside the panel, they dont show any values. What could be the reason for this?
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Jan 17, 2010
how i persist the selected date of calendar control on Postback iam displaying Dates from database in to Calendar control and when page postback then nothing is heppening . How i persist the selected dates on Postback may i have to use Session or some thing like that?
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Apr 4, 2011
Alright, so here's my basic ASP.NET page setup: I've got a page with a GridView that has ContentTemplates in it. You can add a row and edit/remove rows at any time. There's a "New" button that creates a new row.
All of this data is bound to custom data objects. So if I have a GridView of "People" and each row has "FirstName", "LastName", and "Gender" (with TextBox and DropDown controls), I then have a "Person" object which has public properties for "FirstName", "LastName", etc. I have the binding set up correctly, and I can push data into the GridView from the object, and I persist the object with the Session variable. My page lifetime structure looks something like this:
Page_Load: Loads the List(Of Person) from Session()
Any events fire, and modify the List(Of Person).After any event, the List(Of Person) gets saved back into Session(), and is then DataBound to the GridView (and any subsequent fields are also DataBound, such as the DropDownList.
My question is: Whenever I fill in rows in the GridView, and then add a new row (there is no database saving going on whatsoever), my fields clear out and don't persist across PostBacks. So, how can I persist my custom data objects with databinding across postbacks?
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Apr 7, 2010
Im using Nested DataList in My Application. But i m not able to find control Inside Child DataList. (I want to Find Label Control In ItemDataBound Of ChildDataList)
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Aug 23, 2010
I am trying to find a child control from a repeater control's child control. I have the following structure like a top control is a repeater, below which is a Panel and below this is a DateControl(custom control).
I want to find the DateControl.
<asp:Repeater runat="server"
ID="rptMembers"
<ItemTemplate>
<asp:Panel ID="pnlAddDependent".....
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Mar 2, 2010
I've got a FormView control for which I'm Viewing, Inserting and Updating to a MS SQL Database.
Instead of adding a SqlDataSource control to the page, I've created it in the code behind and declaring the properties/attributes for it during Page_Load.
At the moment, everything is bound and working fine, but I'm having an issue Databinding to the child controls in my FormView with parameters set in the code behind.
This is where I'm at.
[Code]....
[Code]....
So, I need to be able to bind the DS.InsertParameters.Add("PageTitle", ---) with the txPageTitle control in the Insert Template, same with the PageURL to txPageURL. Is there any easy way to do this from the code behind? I can't seem to find a way to add a parameter without needing to assign it a value.
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Dec 31, 2012
URL...
<asp:GridView ID="gvCustomers" runat="server" AutoGenerateColumns="false" CssClass="Grid"
onrowdatabound="gvCustomers_RowDataBound" Width="100%"
onrowcommand="gvCustomers_RowCommand" >
<RowStyle HorizontalAlign="Center" />
<AlternatingRowStyle HorizontalAlign="Center" />
<Columns>
<asp:TemplateField>
[code]....
and also i tried
GridView gvchild = e.Row.FindControl("gvOrders") as GridView; drplist = gvchild.FindControl("drp1") as DropDownList; // den also same error object reference not set to an instance of an obj
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Dec 17, 2012
How To presist data using spring cotext in C# asp.net enviorn ment.
I have a class with username and user id properties.
at the time of loging i am creating class object and assinging values to properties.
Now i want to presist this object in Spring context. is it possible if Yes How?
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Mar 29, 2011
I have a requirement as mentioned below: 1. There is a gridview containing a linkbutton field (lnkgdvMerchant)in one of the column defination as menioned in the mark up below :Please note the bolded line of code for more details.
[Code]....
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Nov 12, 2010
I add cache to my application, I have a page which contains several User Control, my problem is I just want to cache the data returned from Controller, but not want to cache all the page content. Since one of my user control is login control, if I cache all the result, then it will behave incorrectly.
my problem is :
1.Is it possible to just cache the data returned from controller ?
2.If a page is cached, can I force a control in the page to be uncached ?
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Jan 27, 2011
in the gridview control when user edit the row and click on update button to save and then click on refresh button (IE) it execut the update event again.
how should i avoid if the user click on refresh after it updates the row?
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Sep 4, 2010
I would like to know how to add some additional child nodes to a custom user control class derived from System.Web.UI.Control. For example currently I have a control that contains no child nodes and on the design surface looks like the following.
<cust:MyCustomControl id="ctlMyCustomControl" runat="server" attribute1="somevalue" attribute2="somevalue" ></MyCustomControl>
What I am looking for is to have the ability to add n number of child nodes to this control from the design surface and then access their values from the code. So adding to the control stated above.
<cust:MyCustomControl id="ctlMyCustomControl" runat="server" attribute1="somevalue" attribute2="somevalue" >
<childnode1>value1</childnode1>
<childnode2>value2</childnode2>
</MyCustomControl>
It is not clear to me how to access the child nodes.
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