How can I limit a string if it's larger than desired? - asp.net

I currently have a string that I want to limit to 200 characters.
I don't know how to format it so if it's less, it wont change, but if its more, it will trim it.
This is in a ListView Control, NOT a Repeater. Sorry for that, my mistake.
<ItemTemplate>
<div class="portfolio_title">
<div class="custom_title">
<%# DataBinder.Eval(Container.DataItem, "Title")%></div>
</div>
<asp:Literal ID="LiteralArticle" runat="server"></asp:Literal>
<%# DataBinder.Eval(Container.DataItem, "Article")%><br />
Read Full Article...
<div class="page_line">
</div>
</ItemTemplate>

Here is some code that I use for this sort of thing. Attach this to the OnRowDataBound event. This truncates to 50 characters and adds elipses "...".
protected void CommentGridViewRowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
TableCell cell = e.Row.Cells[0];
if (!string.IsNullOrEmpty(cell.Text) && cell.Text.Length > 50)
{
cell.Text = cell.Text.Substring(0, 50) + "…";
}
}
}

Do you mean like...
int maxLength = 200;
string trimmed = (trimmed.length > maxLength) ? trimmed.Substring(0,maxlength) : trimmed ;

I assume this is going in a grid or something... I'd call a function and pass your Eval as an argument:
My example:
<asp:Image ID="imgTopLevelTickCross" runat="server" ImageUrl='<%# "/images/" & getImage(Eval("DrwgID").toString()) & ".gif" %> ' />
The ImageURL calls getImage and passes the value of Eval("DrwgID") to it to form the src path
Public Function getImage(ByVal drwgID As Integer) As String
If TopLevelDrwgID = drwgID Then
Return "True"
Else
Return "blank"
End If
End Function

It's maybe a litte more than you need, but works well for me in most cases. It preserves the file ending, if you deal with files and adds "..." at the end of the shortend string if you want.
/// <summary>
/// Shortens a long string. Optionally keeps the file ending and adds a placeholder at the end.
/// </summary>
/// <example>
/// Input: ThisIsAVeryLongFilenameForThisTest.doc (length=10, placeholder='...', saveFileEnding=true)
/// Output: ThisIsAVeryLong
/// </example>
/// <param name="value"></param>
/// <param name="length"></param>
/// <param name="placeHolder"></param>
/// <param name="saveFileEnding"></param>
/// <returns></returns>
public static string ShowSummary(string value, int length, string placeHolder, bool saveFileEnding)
{
int lengthNew = length;
string fileEnding = "";
//nothing to do if the string is short enough
if (length > value.Length)
{
return value;
}
if (saveFileEnding)
{
int index = value.LastIndexOf(".");
if (index != -1)
{
fileEnding = value.Substring(index);
lengthNew = length - fileEnding.Length;
}
}
//substract the length of the placeholder
lengthNew = lengthNew - placeHolder.Length;
if (lengthNew > 0)
{
return value.Substring(0, lengthNew) + placeHolder + fileEnding;
}
else
{
//something is weird, maybe a really long filending or a '.' in the filename, so just cut it down
return value.Substring(0, length);
}
}//ShowSummary

Related

set selected value based off parent value

I have 2 cascading drop downs, 1 is a parent and the other/child populates once you select a value in the first/parent drop down.
The first one populates on page load and I can set the selected value for this one based off database value that was saved on previous page.
For the second cascading drop down it populates for me when I set the selected value for the parent ID on page load (based off the database value).
But since the second/child drop down is not set/loaded with values until the page loads I can not set the selected value (I tried on Page_Load_Complete but it does not work there either).
I need to know how once I set the selected value in the parent drop down (this works fine), to populate the second drop down based off the value in the first one.
Here is my code for the aspx page. I can set the first selected value, and it populates the second select box (but I can not set the selected value because it is not populated at the time I set the first selected value.
aspx page
<asp:Label ID="lblAffPartCat" Text="<%$ Resources:share,lblAffPartCat %>" runat="server"></asp:Label>
<asp:DropDownList ID="ddlPartCat" runat="server"></asp:DropDownList>
<ajaxToolkit:CascadingDropDown ID="CascadingDropDown2" runat="server" TargetControlID="ddlPartCat"
Category="BasePart" PromptText="<%$ Resources:share,lblSelPartCat %>" LoadingText="[Loading Part Cat...]"
ServicePath="PAIntExtPart.asmx" ServiceMethod="BindPartCat"
ContextKey="" UseContextKey="True"/>
<asp:Label ID="lblAffBasePart" Text="<%$ Resources:share,lblAffBasePart %>" runat="server"></asp:Label>
<asp:DropDownList ID="ddlBasePart" runat="server" ></asp:DropDownList>
<ajaxToolkit:CascadingDropDown ID="ddlBasePart_CascadingDropDown" runat="server" Category="BasePart"
TargetControlID="ddlBasePart" ParentControlID= "ddlPartCat" PromptText="<%$ Resources:share,lblSelBasePart %>"
LoadingText="Loading Base Parts.."
ServicePath="PAIntExtPart.asmx"
ServiceMethod="BindBasePart"
ContextKey="" UseContextKey="True" />
asmx.cs page that populates the drop downs:
using System;
using System.Collections.Generic;
using System.Web.Services;
using System.Data;
using System.Collections.Specialized;
using AjaxControlToolkit;
using Hotline.DataAccess;
/// <summary>
/// Summary description for PAIntExtPart
/// </summary>
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.ComponentModel.ToolboxItem(false)]
// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.
[System.Web.Script.Services.ScriptService()]
public class PAIntExtPart : System.Web.Services.WebService
{
string _SiteLocation = MiscFunctions.getCurrentSiteLocation();
/// <summary>
/// WebMethod to Populate Part Category Dropdown
/// </summary>
[WebMethod]
public CascadingDropDownNameValue[] BindPartCat(string knownCategoryValues, string category, string contextKey)
{
DataTable dsPartCat = null;
// string passed for contextKey is FormType and Language split by ":"
string[] arrcontextKey = contextKey.Split(':');
string FormType = arrcontextKey[0].ToString();
int LanguageID = Int32.Parse(arrcontextKey[1].ToString());
string PartCatValue = arrcontextKey[2].ToString();
try
{
dsPartCat = HarDB.getPartCat(_SiteLocation, LanguageID, FormType);
//create list and add items in it by looping through dataset table
List<CascadingDropDownNameValue> PartCatdetails = new List<CascadingDropDownNameValue>();
foreach (DataRow dtrow in dsPartCat.Rows)
{
string PartCatID = dtrow["PartCatID"].ToString();
string PartCat = dtrow["PartCat"].ToString();
PartCatdetails.Add(new CascadingDropDownNameValue(PartCat, PartCatID));
}
if (PartCatValue.Trim() != "")
{
//SelectedValue = PartCatValue;
}
return PartCatdetails.ToArray();
}
catch (Exception ex)
{
Server.Transfer("Errorpage.aspx?function=getAttachInfo+Error=" + Server.UrlEncode(ex.Message));
return null;
}
}
/// <summary>
/// WebMethod to Populate Base Part Dropdown
/// </summary>
[WebMethod]
public CascadingDropDownNameValue[] BindBasePart(string knownCategoryValues, string category, string contextKey)
{
string PartCatID;
//int LanguageID = Int32.Parse(contextKey);
string[] arrcontextKey = contextKey.Split(':');
string FormType = arrcontextKey[0].ToString();
int LanguageID = Int32.Parse(arrcontextKey[1].ToString());
string BasePartValue = arrcontextKey[2].ToString();
//This method will return a StringDictionary containing the name/value pairs of the currently selected values
StringDictionary PartCatdetails = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
PartCatID = PartCatdetails["BasePart"];
DataTable dsBasePart = null;
try
{
dsBasePart = HarDB.getBasePart(_SiteLocation, LanguageID, PartCatID, FormType);
//create list and add items in it by looping through dataset table
List<CascadingDropDownNameValue> BasePartdetails = new List<CascadingDropDownNameValue>();
foreach (DataRow dtrow in dsBasePart.Rows)
{
string BasePartID = dtrow["BasePartNumID"].ToString();
string BasePart = dtrow["BasePartNum"].ToString();
BasePartdetails.Add(new CascadingDropDownNameValue(BasePart, BasePartID));
}
if (BasePartValue.Trim() != "")
{
//SelectedValue = PartCatValue;
}
return BasePartdetails.ToArray();
}
catch (Exception ex)
{
Server.Transfer("Errorpage.aspx?function=getAttachInfo+Error=" + Server.UrlEncode(ex.Message));
return null;
}
}
}
I found out my issue, I was not using the correct "Selected Value" when trying to populate the second drop down.

in Cascading dropdown update in Ajax Control Toolkit

I am getting [MethodError 500] when I use cascading drop down. below is my code
<tr>
<td >
Select a Hoster:
</td>
<td>
<asp:DropDownList ID="ddlFeaturedHoster" runat="server" ></asp:DropDownList>
</td>
</tr>
<ajaxToolkit:CascadingDropDown ID="cddHoster" runat="server" TargetControlID="ddlFeaturedHoster"
PromptText="Select a Hoster" LoadingText="Loading ..." Category="ActiveHoster"
ServiceMethod="GetDropDownContents" ServicePath="~/Hosting/HostingService.asmx"/>
Service Code:
[WebMethod]
[ScriptMethod]
public CascadingDropDownNameValue[] GetActiveHosters()
{
List<CascadingDropDownNameValue> returnList = new List<CascadingDropDownNameValue>();
HostersManager hosterManager = new HostersManager();
List<Hosters_HostingProviderDetail> hosters = hosterManager.GetAllHosters();
returnList.Add(new CascadingDropDownNameValue("--Please Select One--","0",true));
foreach (Hosters_HostingProviderDetail item in hosters)
{
returnList.Add(new CascadingDropDownNameValue() { name=item.HostingProviderName, value= item.HosterID.ToString()});
}
return returnList.ToArray() ;
}
[WebMethod]
[ScriptMethod]
public CascadingDropDownNameValue[] GetDropDownContents(string knownCategoryValues, string category)
{
knownCategoryValues = FormatCategoryWord(knownCategoryValues);
List<CascadingDropDownNameValue> values = new List<CascadingDropDownNameValue>();
HostersManager hosterManager = new HostersManager();
switch (category)
{
case "ActiveHoster":
values.AddRange(GetActiveHosters());
break;
case "ActiveOffer":
values.AddRange(GetActiveOffers(1));
break;
}
return values.ToArray<CascadingDropDownNameValue>();
}
/// <summary>
/// Formats the category word
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
private string FormatCategoryWord(string value)
{
if (string.IsNullOrEmpty(value)) return value;
if (value.LastIndexOf(":") > 0) value = value.Substring(value.LastIndexOf(":") + 1);
if (value.LastIndexOf(";") > 0) value = value.Substring(0, value.LastIndexOf(";"));
return value;
}
}
How about some try catch blocks within your webMethods with some exception logging?
I kept [ScriptService] attribute on top of service class its working now.

How to validate against Multiple validation groups?

I have two validation groups: parent and child
I have an add button that needs to only validate the child validation group which is easily done. The save button needs to validate against the parent and child validation groups, both client side and server side. I think I know how to do it server side by calling the Page.Validate("groupname") method for each group, but how can it be done client side?
You should be able to accomplish this by creating a javascript function that uses Page_ClientValidate and then having the button call that function
<asp:Button ID="btnSave" Text="Save" OnClientClick="return validate()" runat="server" />
<script type="text/javascript">
function validate() {
var t1 = Page_ClientValidate("parent");
var t2 = Page_ClientValidate("child");
if (!t1 || !t2) return false;
return true;
}
</script>
The problem with CAbbott's answer is that validation errors that occur in the "parent" group will not be displayed after the call to validate the "child" group. The more minor problem with Oleg's answer is that validation of the "child" group will not occur until the "parent" group is ready.
All we really need to do to allow client-side validation of more than one group at the same time is to override the Javascript IsValidationGroupMatch method which determines whether or not a control is to be included in the current set being validated.
For example:
(function replaceValidationGroupMatch() {
// If this is true, IsValidationGroupMatch doesn't exist - oddness is afoot!
if (!IsValidationGroupMatch) throw "WHAT? IsValidationGroupmatch not found!";
// Replace ASP.net's IsValidationGroupMatch method with our own...
IsValidationGroupMatch = function(control, validationGroup) {
if (!validationGroup) return true;
var controlGroup = '';
if (typeof(control.validationGroup) === 'string') controlGroup = control.validationGroup;
// Deal with potential multiple space-delimited groups being validated
var validatingGroups = validationGroup.split(' ');
for (var i = 0; i < validatingGroups.length; i++) {
if (validatingGroups[i] === controlGroup) return true;
}
// Control's group not in any being validated, return false
return false;
};
} ());
// You can now validate against multiple groups at once, for example:
// space-delimited list. This would validate against the Decline group:
//
// Page_ClientValidate('Decline');
//
// while this would validate against the Decline, Open and Complete groups:
//
// Page_ClientValidate('Open Decline Complete');
//
// so if you wanted to validate all three upon click of a button, you'd do:
<asp:Button ID="yourButton" runat="server"
OnClick="ButtonSave_Click" CausesValidation="false"
OnClientClick="return Page_ClientValidate('Open Decline Complete');" />
If you call Page_ClientValidate(..) twice, only the last validation result will be shown and it can be OK while the first is not. So the second call should be made only if the first has returned true
<script type="text/javascript">
var parentOk= Page_ClientValidate('parent');
var childOk = false;
if (parentOk) {
childOk = Page_ClientValidate('child');
}
return parentOk && childOk;
</script>
Whatever way you do it requires some hacking to get round ASP.Net's assumption that you wouldn't try to do this. I favour a reusable approach which is explicit about the hackery involved.
using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace WebSandbox.Validators
{
/// <summary>
/// <para>
/// Validates a different validation group. Among the use cases envisioned are
/// <list type="">
/// <item>
/// Validating one set of rules when the user clicks "Save draft" and validating those rules plus some
/// extra consistency checks when they click "Send".
/// </item>
/// <item>
/// Grouping controls in a <code>fieldset</code> into a validation group with a
/// <code>ValidationSummary</code> and then having a final <code>ValidationSummary</code> which tells the
/// user which groups still have errors.
/// </item>
/// </list>
/// </para>
/// <para>
/// We include checks against setting <code>GroupToValidate</code> to the same value as
/// <code>ValidationGroup</code>, but we don't yet include checks for infinite recursion with one validator
/// in group A which validates group B and another in group B which validates group A. Caveat utilitor.
/// </para>
/// </summary>
public class ValidationGroupValidator : BaseValidator
{
public string GroupToValidate
{
get { return ViewState["G2V"] as string; }
set { ViewState["G2V"] = value; }
}
protected override bool ControlPropertiesValid()
{
if (string.IsNullOrEmpty(GroupToValidate)) throw new HttpException("GroupToValidate not specified");
if (GroupToValidate == ValidationGroup) throw new HttpException("Circular dependency");
// Don't call the base, because we don't want a "control to validate"
return true;
}
protected override void AddAttributesToRender(HtmlTextWriter writer)
{
base.AddAttributesToRender(writer);
writer.AddAttribute("evaluationfunction", "ValidateValidationGroup");
writer.AddAttribute("GroupToValidate", GroupToValidate);
}
protected override void OnPreRender(EventArgs e)
{
// The standard validation JavaScript is too restrictive for this validator to work, so we have to replace a key function.
// Fortunately this runs later than the standard JS, so we can simply overwrite the existing value of Page_ClientValidate.
Page.ClientScript.RegisterStartupScript(typeof(ValidationGroupValidator), "validationJS", _ValidationJS);
base.OnPreRender(e);
}
protected override bool EvaluateIsValid()
{
if (string.IsNullOrEmpty(GroupToValidate)) return false;
bool groupValid = true;
foreach (IValidator validator in Page.GetValidators(GroupToValidate))
{
validator.Validate();
groupValid &= validator.IsValid;
}
return groupValid;
}
private const string _ValidationJS = #"<script type=""text/javascript"">
function ValidateValidationGroup(val) {
if (typeof(val.GroupToValidate) == ""string"") {
val.valid = PageMod_DoValidation(val.GroupToValidate);
}
}
function Page_ClientValidate(validationGroup) {
Page_InvalidControlToBeFocused = null;
if (!Page_Validators) return true;
var i, ctrl;
// Mark everything as valid.
for (i = 0; i < Page_Validators.length; i++) {
Page_Validators[i].finalValid = true;
}
if (Page_ValidationSummaries) {
for (i = 0; i < Page_ValidationSummaries.length; i++) {
Page_ValidationSummaries[i].finalDisplay = ""none"";
}
}
// Validate.
var groupValid = PageMod_DoValidation(validationGroup);
// Update displays once.
for (i = 0; i < Page_Validators.length; i++) {
ctrl = Page_Validators[i];
ctrl.isvalid = ctrl.finalValid;
ValidatorUpdateDisplay(ctrl);
}
if (Page_ValidationSummaries) {
for (i = 0; i < Page_ValidationSummaries.length; i++) {
ctrl = Page_ValidationSummaries[i];
ctrl.style.display = ctrl.finalDisplay;
}
}
ValidatorUpdateIsValid();
Page_BlockSubmit = !Page_IsValid;
return Page_IsValid;
}
function PageMod_DoValidation(validationGroup) {
var groupValid = true, validator, i;
for (i = 0; i < Page_Validators.length; i++) {
validator = Page_Validators[i];
ValidatorValidate(validator, validationGroup, null);
validator.finalValid &= validator.isvalid;
groupValid &= validator.isvalid;
}
if (Page_ValidationSummaries) {
ValidationSummaryOnSubmit(validationGroup, groupValid);
var summary;
for (i = 0; i < Page_ValidationSummaries.length; i++) {
summary = Page_ValidationSummaries[i];
if (summary.style.display !== ""none"") summary.finalDisplay = summary.style.display;
}
}
return groupValid;
}
</script>";
}
}

Setting a WebControls TabIndex based on the ControlId of another control

I have an ASP.NET Webforms site that is regularly having features added.
The majority of time a new WebControl is added to the page and I need to increment the TabIndex to all subsequent controls on the page.
I'd prefer a more robust solution than choosing an arbitrary gap between the initial assigned tab indexes. Setting the tab indexes using the designer tab order functionality is one option but I'd prefer to stay in the source view.
Ideally, if I had, for example, three check boxes I'd like to be able to define the tabindex based off the previous controls tabindex. Then I'd only need to insert the new control and change one existing control.
For example, add a new property TabIndexAfterControlId to WebControl:
<asp:CheckBox ID="checkBoxA" runat="server" TabIndex="1"/>
<asp:CheckBox ID="checkBoxB" runat="server" TabIndexAfterControlId="checkBoxA"/>
<asp:CheckBox ID="checkBoxC" runat="server" TabIndexAfterControlId="checkBoxB"/>
My first thought was to extend System.Web.UI.WebControls.WebControl with a new property, but extension properties aren't supported.
Note: This approach worked for some webcontrols (DropDownLists) but not all of them (CheckBoxes). I've left it here for reference.
I've ended up with a solution that uses a code behind method to capture the relationship between controls.
<asp:CheckBox ID="checkBoxA" runat="server" TabIndex="1"/>
<asp:CheckBox ID="checkBoxB" runat="server" TabIndex='<%# TabIndexAfter(checkBoxB, checkBoxA) %>'/>
<asp:CheckBox ID="checkBoxC" runat="server" TabIndex='<%# TabIndexAfter(checkBoxC, checkBoxB) %>'/>
The code behind method will initially do a basic TabIndex assignment, which works well when the tab order follows the order of the controls on a page. Then during the PreRender event the tab index order will be checked again. This is important if the tab order doesn't not follow the natural flow of the page.
private LinkedList<WebControl> _webControlTabOrder;
/// <summary>
/// Assign the current WebControl TabIndex a value greater than the prior WebControl.
/// </summary>
/// <param name="currentWebControl">The current WebControl to set the TabIndex for</param>
/// <param name="priorWebControl">The prior WebControl to get the previous TabIndex from.</param>
/// <returns>The new TabIndex for the control</returns>
public int TabIndexAfter(WebControl currentWebControl, WebControl priorWebControl)
{
if (_webControlTabOrder == null)
{
_webControlTabOrder = new LinkedList<WebControl>();
this.PreRender += new EventHandler(UserControlBase_PreRender);
}
LinkedListNode<WebControl> priorNode = _webControlTabOrder.Find(currentWebControl);
if (priorNode == null)
{
priorNode = _webControlTabOrder.AddLast(priorWebControl);
}
_webControlTabOrder.AddAfter(priorNode, currentWebControl);
return priorWebControl.TabIndex + 1;
}
void UserControlBase_PreRender(object sender, EventArgs e)
{
LinkedListNode<WebControl> currentNode = _webControlTabOrder.First;
while(currentNode.Next != null)
{
LinkedListNode<WebControl> nextNode = currentNode.Next;
if (nextNode.Value.TabIndex <= currentNode.Value.TabIndex)
{
nextNode.Value.TabIndex = (short)(currentNode.Value.TabIndex + 1);
}
currentNode = nextNode;
}
}
My prior attempt using the data-binding syntax (<%# ... %>) to set the TabIndex for web controls failed when some controls wouldn't bind the TabIndex (CheckBox). It also wasn't ideal as I needed to pass a reference to the current control into the code behind method.
This time around I went with a custom ExpressionBuilder that accepts the name of the web control that the current control should follow in the tab order.
The TabIndexAfterExpressionBuilder initially returns the short -1 as the value. At the same time it registers with the LoadComplete event of the current Page. When this event fires both controls are found and the tab indexes set according to their relative positions.
Example WebControls using the TabIndex Expression Builder
<asp:TextBox ID="txtTextBox0" runat="server" TabIndex="1" /><br />
<asp:TextBox ID="txtTextBox1" runat="server" TabIndex="<%$ TabIndex:txtTextBox0 %>" /><br />
<asp:TextBox ID="txtTextBox2" runat="server" TabIndex="<%$ TabIndex:txtTextBox1 %>" />
TabIndexExpressionBuilder.cs
namespace ExpressionBuilders
{
public class TabIndexExpressionBuilder : ExpressionBuilder
{
public override System.CodeDom.CodeExpression GetCodeExpression(System.Web.UI.BoundPropertyEntry entry, object parsedData, ExpressionBuilderContext context)
{
string priorControlId = entry.Expression.Trim();
string currentControlId = entry.ControlID;
CodeExpression[] inputParams = new CodeExpression[] { new CodePrimitiveExpression(priorControlId),
new CodePrimitiveExpression(currentControlId),
new CodeTypeOfExpression(entry.DeclaringType),
new CodePrimitiveExpression(entry.PropertyInfo.Name) };
// Return a CodeMethodInvokeExpression that will invoke the GetRequestedValue method using the specified input parameters
return new CodeMethodInvokeExpression(new CodeTypeReferenceExpression(this.GetType()),
"GetRequestedValue",
inputParams);
}
public static object GetRequestedValue(string priorControlId, string currentControlId, Type targetType, string propertyName)
{
if (HttpContext.Current == null)
{
return null;
}
Page page = HttpContext.Current.Handler as Page;
if (page != null)
{
page.LoadComplete += delegate(object sender, EventArgs e)
{
WebControl currentWebControl = FindControlRecursive(page, currentControlId);
WebControl priorWebControl = FindControlRecursive(page, priorControlId);
if (currentWebControl != null && priorWebControl != null)
{
TabIndexAfter(page, currentWebControl, priorWebControl);
}
};
}
// Default TabIndex
short value = (short)-1;
return value;
}
private static WebControl FindControlRecursive(Control rootControl, string controlID)
{
if (rootControl.ID == controlID) { return rootControl as WebControl; }
foreach (Control controlToSearch in rootControl.Controls)
{
Control controlToReturn = FindControlRecursive(controlToSearch, controlID);
if (controlToReturn != null)
{
return controlToReturn as WebControl;
}
}
return null;
}
#region Tabbing
/// <summary>
/// Assign the current WebControl TabIndex a value greater than the prior WebControl.
/// </summary>
/// <param name="currentWebControl">The current Control to set the TabIndex for</param>
/// <param name="priorWebControl">The prior Control to get the previous TabIndex from.</param>
/// <returns>The new TabIndex for the current control</returns>
private static short TabIndexAfter(Page page, WebControl currentWebControl, object prior)
{
TabOrderWebControl tabOrderWebControl = page.FindControl("TabOrderWebControl") as TabOrderWebControl;
if (tabOrderWebControl == null)
{
tabOrderWebControl = new TabOrderWebControl();
page.Controls.Add(tabOrderWebControl);
}
WebControl priorWebControl = prior as WebControl;
if (priorWebControl == null)
{
string priorWebControlId = prior as string;
priorWebControl = page.FindControl(priorWebControlId) as WebControl;
}
if (currentWebControl == null) { throw new ArgumentNullException("currentWebControl"); }
if (priorWebControl == null) { throw new ArgumentNullException("priorWebControl"); }
if (currentWebControl == priorWebControl) { throw new ArgumentException("priorWebControl is the same as the currentWebControl", "priorWebControl"); }
tabOrderWebControl.TabIndexAfter(currentWebControl, priorWebControl);
return currentWebControl.TabIndex;
}
#endregion
}
}
TabOrderWebControl.cs
namespace ExpressionBuilders
{
public class TabOrderWebControl :
WebControl
{
LinkedList<WebControl> _webControlTabOrder;
internal void TabIndexAfter(System.Web.UI.WebControls.WebControl currentWebControl, System.Web.UI.WebControls.WebControl priorWebControl)
{
if (_webControlTabOrder == null)
{
_webControlTabOrder = new LinkedList<WebControl>();
this.Page.PreRender += new EventHandler(PageBase_PreRender);
}
LinkedListNode<WebControl> priorNode = _webControlTabOrder.Find(priorWebControl);
LinkedListNode<WebControl> currentNode = _webControlTabOrder.Find(currentWebControl);
if (currentNode != null)
{
//The current node is already in the list (it must preceed some other control)
//Add the prior node before it.
if (priorNode == null)
{
priorNode = _webControlTabOrder.AddBefore(currentNode, priorWebControl);
}
else
{
//Both nodes are already in the list. Ensure the ordering is correct.
bool foundPriorNode = false;
foreach (WebControl controlNode in _webControlTabOrder)
{
if (controlNode == priorWebControl)
{
foundPriorNode = true;
}
else if (controlNode == currentWebControl)
{
if (foundPriorNode)
{
//Ordering is correct
break;
}
else
{
throw new ApplicationException(string.Format("WebControl ordering is incorrect. Found {1} before {0}", currentWebControl.ID, priorWebControl.ID));
}
}
}
}
}
else if (priorNode == null)
{
//Neither control is in the list yet.
priorNode = _webControlTabOrder.AddLast(priorWebControl);
currentNode = _webControlTabOrder.AddAfter(priorNode, currentWebControl);
}
else
{
//Prior node is already in the list but the current node isn't
currentNode = _webControlTabOrder.AddAfter(priorNode, currentWebControl);
}
}
/// <summary>
/// Once all the controls have been added to the linked list ensure the tab ordering is correct.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void PageBase_PreRender(object sender, EventArgs e)
{
AssignTabIndexes();
}
/// <summary>
/// Reassign tab indexes for all known controls.
/// </summary>
protected void AssignTabIndexes()
{
LinkedListNode<WebControl> currentNode = _webControlTabOrder.First;
while (currentNode.Next != null)
{
LinkedListNode<WebControl> nextNode = currentNode.Next;
WebControl currentControl = currentNode.Value;
WebControl nextControl = nextNode.Value;
if (currentControl == nextControl)
{
throw new ApplicationException("Control added twice");
}
short currentTabIndex = currentControl.TabIndex;
short nextTabIndex = nextControl.TabIndex;
if (nextTabIndex <= currentTabIndex)
{
nextControl.TabIndex = (short)(currentTabIndex + 1);
}
currentNode = nextNode;
}
}
}
}
web.config
<system.web>
<compilation debug="true" targetFramework="4.0">
<expressionBuilders>
<add expressionPrefix="TabIndex" type="ExpressionBuilders.TabIndexExpressionBuilder, ExpressionBuilders"/>
</expressionBuilders>
</compilation>
</system.web>

How to decode viewstate

I need to see the contents of the viewstate of an asp.net page. I looked for a viewstate decoder, found Fridz Onion's ViewState Decoder but it asks for the url of a page to get its viewstate. Since my viewstate is formed after a postback and comes as a result of an operation in an update panel, I cannot provide a url. I need to copy & paste the viewstate string and see what's inside. Is there a tool or a website exist that can help viewing the contents of viewstate?
Here's an online ViewState decoder:
http://ignatu.co.uk/ViewStateDecoder.aspx
Edit: Unfortunatey, the above link is dead - here's another ViewState decoder (from the comments):
http://viewstatedecoder.azurewebsites.net/
Use Fiddler and grab the view state in the response and paste it into the bottom left text box then decode.
Here is the source code for a ViewState visualizer from Scott Mitchell's article on ViewState (25 pages)
using System;
using System.Collections;
using System.Text;
using System.IO;
using System.Web.UI;
namespace ViewStateArticle.ExtendedPageClasses
{
/// <summary>
/// Parses the view state, constructing a viaully-accessible object graph.
/// </summary>
public class ViewStateParser
{
// private member variables
private TextWriter tw;
private string indentString = " ";
#region Constructor
/// <summary>
/// Creates a new ViewStateParser instance, specifying the TextWriter to emit the output to.
/// </summary>
public ViewStateParser(TextWriter writer)
{
tw = writer;
}
#endregion
#region Methods
#region ParseViewStateGraph Methods
/// <summary>
/// Emits a readable version of the view state to the TextWriter passed into the object's constructor.
/// </summary>
/// <param name="viewState">The view state object to start parsing at.</param>
public virtual void ParseViewStateGraph(object viewState)
{
ParseViewStateGraph(viewState, 0, string.Empty);
}
/// <summary>
/// Emits a readable version of the view state to the TextWriter passed into the object's constructor.
/// </summary>
/// <param name="viewStateAsString">A base-64 encoded representation of the view state to parse.</param>
public virtual void ParseViewStateGraph(string viewStateAsString)
{
// First, deserialize the string into a Triplet
LosFormatter los = new LosFormatter();
object viewState = los.Deserialize(viewStateAsString);
ParseViewStateGraph(viewState, 0, string.Empty);
}
/// <summary>
/// Recursively parses the view state.
/// </summary>
/// <param name="node">The current view state node.</param>
/// <param name="depth">The "depth" of the view state tree.</param>
/// <param name="label">A label to display in the emitted output next to the current node.</param>
protected virtual void ParseViewStateGraph(object node, int depth, string label)
{
tw.Write(System.Environment.NewLine);
if (node == null)
{
tw.Write(String.Concat(Indent(depth), label, "NODE IS NULL"));
}
else if (node is Triplet)
{
tw.Write(String.Concat(Indent(depth), label, "TRIPLET"));
ParseViewStateGraph(((Triplet) node).First, depth+1, "First: ");
ParseViewStateGraph(((Triplet) node).Second, depth+1, "Second: ");
ParseViewStateGraph(((Triplet) node).Third, depth+1, "Third: ");
}
else if (node is Pair)
{
tw.Write(String.Concat(Indent(depth), label, "PAIR"));
ParseViewStateGraph(((Pair) node).First, depth+1, "First: ");
ParseViewStateGraph(((Pair) node).Second, depth+1, "Second: ");
}
else if (node is ArrayList)
{
tw.Write(String.Concat(Indent(depth), label, "ARRAYLIST"));
// display array values
for (int i = 0; i < ((ArrayList) node).Count; i++)
ParseViewStateGraph(((ArrayList) node)[i], depth+1, String.Format("({0}) ", i));
}
else if (node.GetType().IsArray)
{
tw.Write(String.Concat(Indent(depth), label, "ARRAY "));
tw.Write(String.Concat("(", node.GetType().ToString(), ")"));
IEnumerator e = ((Array) node).GetEnumerator();
int count = 0;
while (e.MoveNext())
ParseViewStateGraph(e.Current, depth+1, String.Format("({0}) ", count++));
}
else if (node.GetType().IsPrimitive || node is string)
{
tw.Write(String.Concat(Indent(depth), label));
tw.Write(node.ToString() + " (" + node.GetType().ToString() + ")");
}
else
{
tw.Write(String.Concat(Indent(depth), label, "OTHER - "));
tw.Write(node.GetType().ToString());
}
}
#endregion
/// <summary>
/// Returns a string containing the <see cref="IndentString"/> property value a specified number of times.
/// </summary>
/// <param name="depth">The number of times to repeat the <see cref="IndentString"/> property.</param>
/// <returns>A string containing the <see cref="IndentString"/> property value a specified number of times.</returns>
protected virtual string Indent(int depth)
{
StringBuilder sb = new StringBuilder(IndentString.Length * depth);
for (int i = 0; i < depth; i++)
sb.Append(IndentString);
return sb.ToString();
}
#endregion
#region Properties
/// <summary>
/// Specifies the indentation to use for each level when displaying the object graph.
/// </summary>
/// <value>A string value; the default is three blank spaces.</value>
public string IndentString
{
get
{
return indentString;
}
set
{
indentString = value;
}
}
#endregion
}
}
And here's a simple page to read the viewstate from a textbox and graph it using the above code
private void btnParse_Click(object sender, System.EventArgs e)
{
// parse the viewState
StringWriter writer = new StringWriter();
ViewStateParser p = new ViewStateParser(writer);
p.ParseViewStateGraph(txtViewState.Text);
ltlViewState.Text = writer.ToString();
}
As another person just mentioned, it's a base64 encoded string. In the past, I've used this website to decode it:
http://www.motobit.com/util/base64-decoder-encoder.asp
JavaScript-ViewState-Parser:
http://mutantzombie.github.com/JavaScript-ViewState-Parser/
https://github.com/mutantzombie/JavaScript-ViewState-Parser/
The parser should work with most non-encrypted ViewStates. It doesn’t
handle the serialization format used by .NET version 1 because that
version is sorely outdated and therefore too unlikely to be
encountered in any real situation.
http://deadliestwebattacks.com/2011/05/29/javascript-viewstate-parser/
Parsing .NET ViewState
A Spirited Peek into ViewState, Part I:
http://deadliestwebattacks.com/2011/05/13/a-spirited-peek-into-viewstate-part-i/
A Spirited Peek into ViewState, Part II:
http://deadliestwebattacks.com/2011/05/25/a-spirited-peek-into-viewstate-part-ii/
Here's another decoder that works well as of 2014: http://viewstatedecoder.azurewebsites.net/
This worked on an input on which the Ignatu decoder failed with "The serialized data is invalid" (although it leaves the BinaryFormatter-serialized data undecoded, showing only its length).
This is somewhat "native" .NET way of converting ViewState from string into StateBag
Code is below:
public static StateBag LoadViewState(string viewState)
{
System.Web.UI.Page converterPage = new System.Web.UI.Page();
HiddenFieldPageStatePersister persister = new HiddenFieldPageStatePersister(new Page());
Type utilClass = typeof(System.Web.UI.BaseParser).Assembly.GetType("System.Web.UI.Util");
if (utilClass != null && persister != null)
{
MethodInfo method = utilClass.GetMethod("DeserializeWithAssert", BindingFlags.NonPublic | BindingFlags.Static);
if (method != null)
{
PropertyInfo formatterProperty = persister.GetType().GetProperty("StateFormatter", BindingFlags.NonPublic | BindingFlags.Instance);
if (formatterProperty != null)
{
IStateFormatter formatter = (IStateFormatter)formatterProperty.GetValue(persister, null);
if (formatter != null)
{
FieldInfo pageField = formatter.GetType().GetField("_page", BindingFlags.NonPublic | BindingFlags.Instance);
if (pageField != null)
{
pageField.SetValue(formatter, null);
try
{
Pair pair = (Pair)method.Invoke(null, new object[] { formatter, viewState });
if (pair != null)
{
MethodInfo loadViewState = converterPage.GetType().GetMethod("LoadViewStateRecursive", BindingFlags.Instance | BindingFlags.NonPublic);
if (loadViewState != null)
{
FieldInfo postback = converterPage.GetType().GetField("_isCrossPagePostBack", BindingFlags.NonPublic | BindingFlags.Instance);
if (postback != null)
{
postback.SetValue(converterPage, true);
}
FieldInfo namevalue = converterPage.GetType().GetField("_requestValueCollection", BindingFlags.NonPublic | BindingFlags.Instance);
if (namevalue != null)
{
namevalue.SetValue(converterPage, new NameValueCollection());
}
loadViewState.Invoke(converterPage, new object[] { ((Pair)((Pair)pair.First).Second) });
FieldInfo viewStateField = typeof(Control).GetField("_viewState", BindingFlags.NonPublic | BindingFlags.Instance);
if (viewStateField != null)
{
return (StateBag)viewStateField.GetValue(converterPage);
}
}
}
}
catch (Exception ex)
{
if (ex != null)
{
}
}
}
}
}
}
}
return null;
}
You can ignore the URL field and simply paste the viewstate into the Viewstate string box.
It does look like you have an old version; the serialisation methods changed in ASP.NET 2.0, so grab the 2.0 version
Best way in python is use this link.
A small Python 3.5+ library for decoding ASP.NET viewstate.
First install that: pip install viewstate
>>> from viewstate import ViewState
>>> base64_encoded_viewstate = '/wEPBQVhYmNkZQ9nAgE='
>>> vs = ViewState(base64_encoded_viewstate)
>>> vs.decode()
('abcde', (True, 1))
Online Viewstate Viewer made by Lachlan Keown:
http://lachlankeown.blogspot.com/2008/05/online-viewstate-viewer-decoder.html
Normally, ViewState should be decryptable if you have the machine-key, right? After all, ASP.net needs to decrypt it, and that is certainly not a black box.

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