CustomValidator.EvaluateIsValid Method ()
.NET Framework (current version)
This API supports the product infrastructure and is not intended to be used directly from your code.
Overrides the BaseValidator.EvaluateIsValid method.
Assembly: System.Web (in System.Web.dll)
The following code example demonstrates how to override the EvaluateIsValid method in a custom server control.
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.CS.Controls" Assembly="Samples.AspNet.CS" %> <%@ Page Language="C#" AutoEventWireup="True" %> <!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 CustomValidator - EvaluateIsValid - C# Example</title> </head> <body> <form id="Form1" method="post" runat="server"> <h3>Custom CustomValidator - EvaluateIsValid - C# Example</h3> <asp:Label id="Label1" runat="server" Text="Enter an even number:" AssociatedControlID="TextBox1" /><br /> <asp:TextBox id="TextBox1" runat="server" /> <aspSample:CustomCustomValidatorEvaluateIsValid id="Customvalidator1" runat="server" ControlToValidate="TextBox1" Display="Static" ErrorMessage="Not an even number!" /><br /><br /> <asp:Button id="Button1" runat="server" Text="Validate" /> </form> </body> </html>
using System.Web; using System.Security.Permissions; namespace Samples.AspNet.CS.Controls { [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)] public sealed class CustomCustomValidatorEvaluateIsValid : System.Web.UI.WebControls.CustomValidator { protected override bool EvaluateIsValid() { bool isValid = false; // Get the name of the control to validate. string controlToValidate = this.ControlToValidate; if (controlToValidate.Length > 0) { // Get the control's value. string controlValue = GetControlValidationValue(controlToValidate); // If the value is not null and not empty, test whether // check if the value entered into the text box is even, // if so return true, else return false in all other cases. if ((controlValue != null) && (!controlValue.Trim().Equals(System.String.Empty))) { try { int i = int.Parse(controlValue); isValid = ((i%2) == 0); } catch {} } } return isValid; } } }
.NET Framework
Available since 1.1
Available since 1.1
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