.NET Tutorials, Forums, Interview Questions And Answers
Welcome :Guest
Sign In
Win Surprise Gifts!!!

Top 5 Contributors of the Month
david stephan
Gaurav Pal
Post New Web Links

ViewState is sometimes empty

Posted By:      Posted Date: September 06, 2010    Points: 0   Category :ASP.Net
Hi,I have a composite control. In the CreateChildControls-Method I read the current display mode from ViewState like this: if (Page.IsPostBack) { AddSubControls(ViewState["Mode"].ToString()); } My problem is that the ViewState is sometimes empty on PostBack. I figured out that it depends from the control which caused the postpack. For example if I change a DropDown value the ViewState isn't empty. Pressing some buttos causes that the viewsate is empty. But why?The Composite control works fine on a view other pages. Only one page causes the problems. Unfortunately the pages which causes the problems is the biggest page on my website. It has multiple tabs with a lot of controls. Any ideas?

View Complete Post

More Related Resource Links

WebPart has empty viewstate on postback

I have a simple weather web part in the form of a user control.  This usercontrol has an update panel and a textbox to allow the user to enter in a zip code/ city etc and an ok button.  The problem comes in when the webpart is added or dragged outside of Zone 1.  If this webpart remains in Zone 1 everything is fine.  If it is in Zone 2 or 3 after entering a zip code and hitting ok and posting back the value of the textbox is always blank.  It seems like the viewstate is cleared or the control is loading for the first time.  I have checked the Page.IsPostBack property and it is indeed True.  What would cause my control to loose the value entered in the textbox only when it resides outside of Zone 1?

How to check for null/empty strings on dynamic objects?


What is the proper way to check for null or empty strings on dynamic objects? This is the only solution I've found so far:

if (admin.PasswordHash.GetType() == typeof(DBNull) || admin.PasswordHash == string.Empty)

If the field is null, the object returned is DBNull.Value, but if the field is empty string, it's return as a System.String object. This makes it impossible to do regular "admin.PasswordHash == DBNull.Value" check, as that will fail whenever the field has been set to empty string. Is my example the right (and only) way to go?

http/localhost is empty


I have Win , I install the following

in Internet Information Service->

Web Management Tools (check)

Application Development Features I check (.Net Extensibility, ASP.net, ISAPIExtensions, ISAPIFilterd,  I can see  IIS Manager under my Administrative tool , but when I call


I  can't see the welcome page , what is wrong

thank you!

Composite Control which contains arbitrary content defined in .aspx of parent and thier ViewState


I want to write own control which can contain other. And I want to define content of the control in the .aspx file where the control is defined. I have written such control. But now I have issue with ViewState of inner controls of my control. The following samle illustrates the issue: I defined two asp:DropDownList ID="ddl1" and ID="ddl2" One of them is inside of my control and other is outside. When posback is occurred asp:DropDownList ID="ddl1 loses state and becomes empty. How to say ASP.net to store state of inner controls defined by this way?


<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="MyControl.ascx.cs" Inherits="DynamicControls.Controls.MyControl" %>

<div class="box">
    <div class="Header-Left">
        <div class="Header-Right">
            My Control
    <div class="Content">
        <asp:PlaceHolder ID="contentPlace" runat="Server" />

Empty template support for GridView


Just add the following to support the empty text in the GridView.


protected override void RenderContents(HtmlTextWriter writer)
	if (Extender.AdapterEnabled)
		GridView gridView = Control as GridView;
		if (gridView != null)
			if ((gridView.Rows.Count == 0) && !String.IsNullOrEmpty(gridView.EmptyDataText))
				writer.WriteAttribute("class", "AspNet-GridView-Empty");

Example of tag to be added to the css
.NiceGridView .AspNet-GridView div.AspNet-GridView-Empty
	border-width: 1px;
	border-style: solid;
	border-color: #

Add an empty line in Gridview on specific dayofweek


Hey all,

Havin quite a bit of trouble with this one.  I have a bunch of days that I worked in my database...mostly monday-friday and some saturdays.  What I want the gridview to do is add an empty line between each sunday and monday so that it seperates out my work weeks and makes it easier to read in the gridview.  I got some help here a few days ago on how to clone the db etc and I have all that working properly but I can't seem to wrap my head around how to do add these empty lines in the proper spots.  Here is my code so far:

private DataTable AddEmptyRow()
        DataTable originalDataTable = GetItems();
        DataTable newDataTable = originalDataTable.Clone();
        DateTime testdate = Convert.ToDateTime("7/20/2010");

            for (int i = 0; i < originalDataTable.Rows.Count; i++)
                DayOfWeek day = testdate.DayOfWeek;

                if (day == DayOfWeek.Sunday)
                    DataRow newDataRow = newDataTable.NewRow();



Empty Website Data Source windown


Hi all,

I am Visual Web Developer user and facing a problem when I am creating a local report (.rdlc) file.

I am using Business objects as the Data Source for this report. It was working perfectly until all the items in the Website Data Source window suddenly "disappeared". The "Add New Data Source" button on this window is also disabled. Now the window is just like a blank box only. And I can't continue working with the report file like this...

I have tried undoing what I did before but it does not help at all...

Any reason for this to happen? There is no sign or something at least indicating what is wrong.

Please help.


 ps: found a similar thread in this forum but not solved

EntityDataSource Where Clause in ViewState?



I have ListView/DataPager on the page that I use together with an EntityDataSource, because I want to filter the results, I programmatically set the Where-property and the WhereParameters of the EntityDataSource.

But: After the Paging-Postback the Value for Where is gone (empty string) whereas the WhereParameters are still there. Isn't the where value saved in ViewState as well? Can I change this behaviour?

Thanx, S.

Custom controls and ViewState management issue



I want to know that when we create custom controls, then is there State Management through ViewState done automatically or we have to handle it explicitely ?Since i have created Custom Controls that is behaving as if it is not maintaining its state on PostBack.

viewstate in a custom control

I am having issues with a simple custom control that I created by subclassing the hyperlink control.

I wanted to create a control called BackLink that would automatically grab the referring url to the page when it first loads the page. and on postbacks it would continue to use the initial value

I am able to capture and set the navigateurl property when the containing page first loads just fine but if the page submits to itself, the control loses its navigateurl value.

I have the enableviewstate property set in the aspx page but it doesn't seem to want to keep its viewstate

Am I missing something? Do I have to manage my own ViewState?

here is my code

public class BackLink : System.Web.UI.WebControls.HyperLink

public BackLink()
this.Text = "<< back";

protected override void Render(HtmlTextWriter output)
if (this.Page.IsPostBack == false)
//save back url
Uri _backUri = this.Context.Request.UrlReferrer;

if(_backUri != null) this.NavigateUrl = _backUri.PathAndQuery;

else this.NavigateUrl = "/";

Dropdown menu - Null or empty string??


I have drop dowm menu as follow.

<asp:ListItem Value="">none</asp:ListItem>
<asp:ListItem Value="STO">Stock</asp:ListItem>
<asp:ListItem Value="ORD">Order</asp:ListItem>

If I chose none, it stores data as "Null"

If I Query the data as below, I don't get the data has value of "Null"

SELECT tabale From type Where type <> STO or type <> ORD

I get data that has empty string but not Null.

Here is my question.

1, How do I write dropdown menu value in oder to get empty string instead of Null?
I did <asp:ListItem Value="">none</asp:ListItem> but this stores Null.

2, Why this Query won't pick up Null?
SELECT mytabale FROM type WHERE type <> STO or type <> ORD

Thank you for your help.

asp.net VS-2005 Website Data Sources is empty



When I create a rdlc file(Report) the dialog box : "Website Data Sources" is empty, I can add a typed dataset, but the buisness objects (Classes) I created sometime disappear and sometime shown,

When I click/ remove some references it show and hide.

I would really appriciate some help,

thanks in advance,


I followed:


It works fine but after a while, it disappears again.

I tried it on several computers(which means it's not a problem of my machine), and tried it on several projects, all behave the same.


VS2005 calling VS2010 asmx service returns empty string


Anyone have any experience with this?

We are using VS 2005 for the front end, and vs 2010 for the web services part (asmx), not wcf yet.


Web service works just like the vs2005 when run locally, no problems.


Connecting to it from a test app returns an empty string. Connecting to a 2005 app doesn't!

Anyone run into this before or have a suggestion? Surely vs 2005 can connect to web services from a later version?






Values in user control fields empty when AutoEventWireup=true ?

As a BizTalk developer I'm trying to build a ASP.NET website so some obvious things might be new to me (so please be gentle). I have a web form and I have a user control on it. This user control contains a panel with some user properties that are to be stored in a database. So far nothing fancy. The user control itself contains a panel and is working fine (all code to retrieve and store the values is working). I used the default settings of creating a user control and one of them was AutoEventWireup=true. This works fine because I also have some dropdown boxes (and other fields) that need to be filled with values from the database and that happens in the Page_load event. The panel specifies the 'DefaultButton' which calls a method when clicked to save the values after the user has changed them. On this click the code of the method is called, I confirmed that, but I found out that the values of my controls on the user control (for example the Textbox control) are empty. As a non-ASP.NET developer I couldn't figure out why. So I changed some settings like AutoEventWireup to false. Off course this resulted in my dropdown boxes no longer to be initially filled, but my surprise was big to find out my controls actually contained the values the user typed in. Logically I need both the values and th

POST from html form viewstate problem

<p> Hi all, I have a website where people need to pay for a specific download (.pdf file). After they payed they get the download(A). My payment-provider can do a HTML-Postback to the site i want, for each succesfull payment. So the idea is that if someone payed, they do a postback to my server with a couple of parameters, so i can know that that specific email address has payed, and they get the download. I tested localy with a .html file on my desktop to postback a set of parameters to my local asp.net website. But in ONLY works if i include the __VIEWSTATE in my html file. And i cant get rid of the viewstate in my HTML of the aspx page. >test.html: <html><head></head><body> <h1>Dit is een test</h1> <form id="form1" action="http://localhost:25659/WebForm1.aspx" method="POST"> <input id="Button1" type="submit" value="submit!"/> 'IT ONLY WORKS IF I INCLUDE THE NEXT LINE: <input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwUKMjA0OTM4MTAwNGRk" /> </form></body></html> Has anybody an idea to acomplish my goal? Maybe i can get some info about the postback in my global.asax? or create a HttpHandler for .html files? Anyone?   Thanks in advance, Vincent   </p>

How to avoid viewstate in page load event??

Hello Everyone, Here Is my scenario,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) So is it any way I can reduce my page/state size??
ASP.NetWindows Application  .NET Framework  C#  VB.Net  ADO.Net  
Sql Server  SharePoint  Silverlight  Others  All   

Hall of Fame    Twitter   Terms of Service    Privacy Policy    Contact Us    Archives   Tell A Friend