I've created a pretty simple custom control that filters items based on categories the user selects in a drop down box.
Here's the error I'mintermittently getting in IE6 and IE7 but not any mozilla-based browsers.
Because of it's intermittent nature it seems like something out of my control...
I've made sure there are no Response.Write(), Response Filters, HttpModules running and that server trace isn't enabled.
I've used Fiddler to look at the responses but can't find the offending part in the error message.
I've googled the error and found this:
http://forums.asp.net/p/1037846/1437627.aspx
I am using a VirtualPathProvider to map requests to items in a cms, but the article above deals with an incorrect formaction being returned in the httpmessage. I've checked the formaction being returned and it is correct.
I'm at a loss. This is a real pain because a lot of time has been invested in using Asp.Net Ajax for our new site and this may make us have to rethink that decision.
Here is the code for my custom control.
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Collections;
using System.Collections.Generic;
using System.Text;
namespace Unwrong.Controls{
publicclassFilterList :Control,INamingContainer
{
privatestring _Category;privateList<FilterListItem> _Items =newList<FilterListItem>();
privateint _MaxVisibleItems;privateint _Position = 0;
privatestring _CssClass;publicstring Category{
get {return _Category; }
set { _Category =value; }}
publicList<FilterListItem> Items{
get {return _Items; }set { _Items =value; }}
publicList<FilterListItem> ItemsInCategory{
get {return GetItemsInCategory(); }}
publicint MaxVisibleItems{
get {return _MaxVisibleItems; }
set { _MaxVisibleItems =value; }}
publicint Position{
get {return _Position; }set { _Position =value; }}
publicstring CssClass{
get {return _CssClass; }
set { _CssClass =value; }}
protectedoverridevoid OnInit(EventArgs e){
Page.RegisterRequiresControlState(this);base.OnInit(e);}
protectedoverridevoid AddParsedSubObject(Object obj){
if (objis Unwrong.Controls.FilterListItem){
Items.Add((Unwrong.Controls.FilterListItem)obj);}
}
protectedoverridevoid CreateChildControls(){
System.Collections.IEnumerator myEnumerator = Items.GetEnumerator();while (myEnumerator.MoveNext())
this.Controls.Add((FilterListItem)myEnumerator.Current);}
protectedoverrideobject SaveControlState(){
FilterListViewstate state =newFilterListViewstate();state.Category = Category;
state.Position = Position;
return state;}
protectedoverridevoid LoadControlState(object state){
if (state !=null){
Category = ((FilterListViewstate)state).Category;Position = ((FilterListViewstate)state).Position;}
}
protectedoverridevoid Render(HtmlTextWriter w){
List<FilterListItem> itemsToDisplay = GetDisplayItems();w.Write(@dotnet.itags.org."<script language='javascript' type='text/javascript'><!--
function hide(id){
try{
var obj=$get(id);
obj.style.visibility='hidden';
}catch(e){}
}
function show(id){
try{
var obj=$get(id);
obj.style.visibility='visible';
}catch(e){}
}
//-->
</script>
");w.Write("<div class=\"column1\">");w.Write(GetItemsInColumn(0));
w.Write("</div>");
w.Write("<div class=\"column2\">");w.Write(GetItemsInColumn(2));
w.Write("</div>");w.Write("<div class=\"column3\">");w.Write(GetItemsInColumn(4));
w.Write("</div>");}
privatestring GetItemsInColumn(int index){
List<FilterListItem> items = GetDisplayItems();
// Check if any items are at the necessary indeces.
if (items.Count > index){
StringBuilder sbHtml =newStringBuilder();// Create the html for two projects.
for (int i = 0; i < 2; i++){
index += i;
if (items.Count > index){
FilterListItem item = items[index];sbHtml.Append("<div class=\"project\" ");
sbHtml.Append("onmouseover=\"this.style.backgroundColor='#E1E1E1'; hide('" + ClientID +"_title" + index +"'); show('" + ClientID +"_details" + index +"');\" ");sbHtml.Append("onmouseout=\"this.style.backgroundColor='#FAFAFA'; show('" + ClientID +"_title" + index +"'); hide('" + ClientID +"_details" + index +"');\" ");
sbHtml.Append(">");if (!String.IsNullOrEmpty(item.ProjectLink)){
sbHtml.Append("<a href=\"" + item.ProjectLink +"\"><img src=\"" + item.Image +"\" alt=\"" + item.Title +"\" title=\"" + item.Title +"\" /></a>");}
elseif (!String.IsNullOrEmpty(item.LiveLink)){
sbHtml.Append("<a href=\"" + item.LiveLink +"\" target=\"_blank\"><img src=\"" + item.Image +"\" alt=\"" + item.Title +"\" title=\"" + item.Title +"\" /></a>");}
else
{
sbHtml.Append("<img src=\"" + item.Image +"\" alt=\"" + item.Title +"\" title=\"" + item.Title +"\" />");}
sbHtml.Append("<div id=\"" + ClientID +"_title" + index +"\" class=\"title\">");sbHtml.Append(item.Title);
sbHtml.Append("</div>");sbHtml.Append("<div id=\"" + ClientID +"_details" + index +"\" class=\"details\">");
if (!String.IsNullOrEmpty(item.ProjectLink)){
sbHtml.Append("<a href=\"" + item.ProjectLink +"\">View Details</a>");}
else
{
sbHtml.Append("<span class=\"strikethrough\">View Details</span>");}
if (!String.IsNullOrEmpty(item.LiveLink)){
sbHtml.Append("<br/><a href=\"" + item.LiveLink +"\" target=\"_blank\">View Live</a>");}
else
{
sbHtml.Append("<br/><span class=\"strikethrough\">View Live</span>");}
sbHtml.Append("</div>");sbHtml.Append("</div>");}
}
return sbHtml.ToString();}
else
{
returnstring.Empty;}
}
privateList<FilterListItem> GetItemsInCategory(){
List<FilterListItem> itemsInCategory =newList<FilterListItem>();// Remove all items that aren't in current category.
foreach (FilterListItem itemin Items){
if (IsItemInCategory(item)){
itemsInCategory.Add(item);
}
}
return itemsInCategory;}
privateList<FilterListItem> GetDisplayItems(){
List<FilterListItem> itemsInCategory = GetItemsInCategory();List<FilterListItem> itemsToDisplay =newList<FilterListItem>();
int count = MaxVisibleItems;if (Position + MaxVisibleItems > itemsInCategory.Count){
count = itemsInCategory.Count - Position;
}
return itemsInCategory.GetRange(Position, count);}
privatebool IsItemInCategory(FilterListItem item){
if (String.IsNullOrEmpty(Category) || Category.ToLower() =="all"){
returntrue;}
foreach (string cin item.Categories){
if (c.ToLower().Trim() == Category.ToLower().Trim()){
returntrue;}
}
returnfalse;}
}
[Serializable]publicclassFilterListViewstate
{
publicstring Category;publicint Position;}
}
Here is the code for page where it is used:
<asp:UpdatePanelID="UpdatePanel1"runat="server"UpdateMode="Conditional">
<ContentTemplate>
<tableid="filter-widget-bar"cellpadding="0"cellspacing="0"border="0">
<tr>
<tdclass="col1">
<imgsrc="/assets_new/images/projects.gif"alt="Projects"/>
</td>
<tdclass="col2">
<tableid="filter-widget"cellpadding="0"cellspacing="0"border="0">
<tr>
<td>
<ctrl:ImageButtonID="btnPreviousProject"runat="server"CssClass="previous"ImageUrl="~/assets_new/images/btn_previous.gif"OnClick="btnPreviousProject_Click"BorderWidth="0"AlternateText="Previous"/>
</td>
<td>
<asp:DropDownList
ID="lstFilter"
OnSelectedIndexChanged="lstFilter_OnSelectedIndexChanged"
AutoPostBack="true"
runat="server">
<asp:ListItem>Favourites</asp:ListItem>
<asp:ListItem>All</asp:ListItem><asp:ListItem>Games</asp:ListItem>
<asp:ListItem>Websites</asp:ListItem>
<asp:ListItem>Applications</asp:ListItem>
<asp:ListItem>Playthings</asp:ListItem>
<asp:ListItem>Cms</asp:ListItem>
<asp:ListItem>Flash</asp:ListItem>
<asp:ListItem>Html</asp:ListItem>
</asp:DropDownList>
</td>
<td>
<ctrl:ImageButtonID="btnNextProject"runat="server"CssClass="next"ImageUrl="~/assets_new/images/btn_next.gif"OnClick="btnNextProject_Click"BorderWidth="0"AlternateText="Next"/>
</td>
</tr>
</table>
</td>
<tdclass="col3">
</td>
</tr>
</table>
<divid="projects">
<ctrl:FilterListID="lstProjects"runat="server"MaxVisibleItems="6">
<ctrl:FilterListItemrunat="server"Image="repository/uploads/projects/ilovedust.jpg"Title="ILoveDust"ProjectLink="http://www.unwrong.com/projects/ilovedust/"LiveLink="http://www.ilovedust.com">
<ctrl:Categoriesrunat="server">
<ctrl:Categoryrunat="server">Flash</ctrl:Category>
<ctrl:Categoryrunat="server">Cms</ctrl:Category>
<ctrl:Categoryrunat="server">Favourites</ctrl:Category>
<ctrl:Categoryrunat="server">Websites</ctrl:Category>
</ctrl:Categories>
</ctrl:FilterListItem>
<ctrl:FilterListItemrunat="server"Image="repository/uploads/projects/tado.jpg"Title="Tado"ProjectLink="http://www.unwrong.com/projects/tado/"LiveLink="http://www.tado.co.uk">
<ctrl:Categoriesrunat="server">
<ctrl:Categoryrunat="server">Flash</ctrl:Category>
<ctrl:Categoryrunat="server">Favourites</ctrl:Category>
<ctrl:Categoryrunat="server">Websites</ctrl:Category>
</ctrl:Categories>
</ctrl:FilterListItem>
<ctrl:FilterListItemrunat="server"Image="repository/uploads/projects/communicatorworld.jpg"Title="Communicator World"ProjectLink="http://www.unwrong.com/projects/communicator/"LiveLink="http://www.communicatorworld.co.uk">
<ctrl:Categoriesrunat="server">
<ctrl:Categoryrunat="server">Flash</ctrl:Category>
<ctrl:Categoryrunat="server">Cms</ctrl:Category>
<ctrl:Categoryrunat="server">Favourites</ctrl:Category>
<ctrl:Categoryrunat="server">Websites</ctrl:Category>
</ctrl:Categories>
</ctrl:FilterListItem></ctrl:FilterList>
</div>
</ContentTemplate>
</asp:UpdatePanel>
Hi,smeeg
This happens when the machineKey used to encrypt/decrypt the viewstate was changed, and more likely this will happen if you keep the page idle for a long time. To avoid this, you need to have a static machineKey.
Check this articlehttp://blog.g9th.com/2007/01/14/unable-to-validate-data-at-systemwebconfigurationmachinekeysectiongetdecodeddata.aspx
Let me know if you need more info.
You can also see this thread for more help:http://forums.asp.net/t/1115331.aspx
Thanks
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