ASP.NET CustomValidator to specific Control

ASP.NET CustomValidator is used to customize and implement data validation to a specific Control. The CompareValidator control belongs to System.Web.UI.WebControls

Syntax

<asp:CustomValidator ID="txtZipValidation" runat="server" 
ErrorMessage="Valid Zip Code is required (ex: #####)" 
ControlToValidate="txtZip" ClientValidationFunction="validateZipCode">
</asp:CustomValidator>

ASP.NET CustomValidator Control Property

Property	Description
ControlToValidate	Specifies control name which needs to be validate.
Display	Specifies behavior of the error message.
EnableClientScript	Specifies whether or not client-side validation is enabled.
Enabled	Specifies whether or not validation control is enabled or not.
ErrorMessage	Specifies error messageto be display in validation summary.
ForeColor	Specifies error message color.
IsValid	Indicate if associate control passes validation or not.
SetFocusOnError	Set focus on associate control if validation fails.
Text	Specifies text to be display if validation fails.
ValidationGroup	Specifies validation group name.
Validate	Update the isvalid propery.
ValidateGetValidationProperty	Determineing validation property of a control, if it exists.

ClientValidationFunction	Specifies custom client-side script function name.
ValidateEmptyText	Set whether empty text should validate or not.
ServerValidate	Set whether you want server-side validation.

ASP.NET CustomValidator to specific Control Example

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" 
Inherits="_Default" %>
<!DOCTYPE html>
<html xmlns="https://www.w3.org/1999/xhtml">
<head runat="server">
<title>ASP.NET CustomValidator Control Example</title>
<script type="text/javascript">
function validateZipCode(sender, args) {
    var val = args.Value;
    var regEx = /^[0-9]+$/;

    if (!regEx.test(val)) {
        args.IsValid = false;
    }
    else {
        if (val.length == 5) {
            if (val > 0) {
                args.IsValid = true;
            }
            else {
                args.IsValid = false;
            }
        }
        else
            args.IsValid = false;
    }
}
</script>
</head>
<body>
<form id="Form" runat="server">
<div>
<asp:Label ID="lblTitle" runat="server" Font-Bold="True" Font-Size="Medium" 
Font-Underline="True" Text="ASP.NET CustomValidator Control Example"></asp:Label>
<br /><br />
<asp:Label ID="lblZipCode" runat="server" Font-Bold="True" Font-Size="Small" 
Text="Enter Zip Code:"></asp:Label>
<asp:TextBox ID="txtZip" runat="server"  CssClass="profileFormObject" Width="53"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" 
ControlToValidate="txtZip" 
ErrorMessage="This is required field, can not be blank."></asp:RequiredFieldValidator>
<asp:CustomValidator ID="txtZipValidation" runat="server" 
ErrorMessage="Valid Zip Code is required (ex: #####)" 
ControlToValidate="txtZip" ClientValidationFunction="validateZipCode">
</asp:CustomValidator>
<br />
<asp:Button ID="btnSubmit" runat="server" Font-Bold="True" 
Font-Size="Small" Text="Submit" />  
</div>
</form>
</body>
</html>

Above example will produce following output