CompareValidator.EvaluateIsValid Method

This method supports the .NET Framework infrastructure and is not intended to be used directly from your code.

When overridden in a derived class, this method contains the code to determine whether the value in the input control is valid.

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 so that it always returns true if the values of the two specified controls are the same and false otherwise.

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" Assembly="Samples.AspNet.JSL" %>
<%@ Page language="VJ#" %>
<!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 - VJ# 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.
        get_Page().Validate();
    } //Page_Load
    </script>
    </head>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom CompareValidator - EvaluateIsValid - VJ# Example</h3>
            
      <asp:TextBox id="TextBox1" runat="server" Text="123"></asp:TextBox><br />
      
      <asp:TextBox id="TextBox2" runat="server" Text="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>

	...

package Samples.AspNet;

public class CustomCompareValidatorEvaluateIsValid
    extends System.Web.UI.WebControls.CompareValidator
{
    protected boolean EvaluateIsValid()
    {
        // Get the values from the two controls
        String controlToValidateValue = this.GetControlValidationValue(
            this.get_ControlToValidate());
        String controlToCompareValue = this.GetControlValidationValue(
            this.get_ControlToCompare());
        // If the values are the same, return true, else return false.
        if (System.String.Compare(controlToValidateValue, 0, 
            controlToCompareValue, 0, controlToCompareValue.get_Length(), 
            false, System.Globalization.CultureInfo.get_InvariantCulture()) ==
            0) {
            return true;
        }
        else {
            return false;
        }
    } //EvaluateIsValid
} //CustomCompareValidatorEvaluateIsValid

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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