CustomValidator.EvaluateIsValid Method

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.WebControls
Assembly: System.Web (in system.web.dll)

protected:
virtual bool EvaluateIsValid () override
protected boolean EvaluateIsValid ()
protected override function EvaluateIsValid () : boolean
Not applicable.

Return Value

true if the value in the input control is valid; otherwise, false.

The following code example demonstrates how to override the EvaluateIsValid method in a custom server control.

Security noteSecurity 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).

No code example is currently available or this language may not be supported.
<%@ 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" />&nbsp;

    <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

Windows 98, Windows Server 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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