CustomValidator.EvaluateIsValid Method
.NET Framework 3.0
This method supports the .NET Framework infrastructure and is not intended to be used directly from your code.
Overrides the BaseValidator.EvaluateIsValid method.
Namespace: System.Web.UI.WebControlsAssembly: System.Web (in system.web.dll)
The following code example demonstrates how to override the EvaluateIsValid method in a custom server control.
Security Note: |
|---|
| 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 (Visual Studio). |
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSL.Controls" Assembly="Samples.AspNet.JSL" %>
<%@ Page Language="VJ#" 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 - VJ# Example</title>
</head>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom CustomValidator - EvaluateIsValid - VJ# 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>
...
package Samples.AspNet.JSL.Controls;
public class CustomCustomValidatorEvaluateIsValid
extends System.Web.UI.WebControls.CustomValidator
{
protected boolean EvaluateIsValid()
{
boolean isValid = false;
// Get the name of the control to validate.
String controlToValidate = this.get_ControlToValidate();
if (controlToValidate.get_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(""))) {
try {
int i = System.Int32.Parse(controlValue);
isValid = i % 2 == 0;
}
catch (System.Exception exp) {
}
}
}
return isValid;
} //EvaluateIsValid
} //CustomCustomValidatorEvaluateIsValid
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