CompareValidator.EvaluateIsValid Method
When overridden in a derived class, this method contains the code to determine whether the value in the input control is valid.
Assembly: System.Web (in System.Web.dll)
The following code example demonstrates how to override the EvaluateIsValid method in a custom server control so that it always returns true if the values of the two specified controls are the same and false otherwise.
Security Note
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This example has a text box that accepts user input, which is a potential security threat. By default, ASP.NET Web pages validate that user input does not include script or HTML elements. For more information, see Script Exploits Overview. |
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet" Assembly="Samples.AspNet.CS" %> <%@ Page language="c#" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head> <title>Custom CompareValidator - EvaluateIsValid - C# Example</title> <script runat="server"> void Page_Load(Object sender, EventArgs e) { // Run the Page Validate method in order to force // the CompareValidate to show it's error message. Page.Validate(); } </script> </head> <body> <form id="Form1" method="post" runat="server"> <h3>Custom CompareValidator - EvaluateIsValid - C# Example</h3> <asp:TextBox id="TextBox1" runat="server">123</asp:TextBox><br /> <asp:TextBox id="TextBox2" runat="server">123</asp:TextBox> <aspSample:CustomCompareValidatorEvaluateIsValid id="CompareValidator1" runat="server" ErrorMessage="Value in TextBox2 does not match value in TextBox1." Display="Dynamic" ControlToCompare="TextBox2" ControlToValidate="TextBox1" /><br /> <asp:Button id="Button1" runat="server" Text="Button" /> </form> </body> </html> ... using System.Web; using System.Security.Permissions; namespace Samples.AspNet { [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)] public sealed class CustomCompareValidatorEvaluateIsValid : System.Web.UI.WebControls.CompareValidator { protected override bool EvaluateIsValid() { // Get the values from the two controls string controlToValidateValue = this.GetControlValidationValue(this.ControlToValidate); string controlToCompareValue = this.GetControlValidationValue(this.ControlToCompare); // If the values are the same, return true, else return false. if (System.String.Compare(controlToValidateValue, 0, controlToCompareValue, 0, controlToCompareValue.Length, false, System.Globalization.CultureInfo.InvariantCulture) == 0) { return true; } else { return false; } } } }
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
