For any application, validation performs a key role. For this Microsoft provides the following types of validators:
1. Required Field validator
2. Regular Expression Validator
3. Range Validator
4. Compare Validator
5. Custom Validator
6. Validation Summary
In this article, we are going to see about Required Field Validator. Add a new Page using Right click on Solution on the context Menu choose Add New Item and select the “Web Form.aspx”.
After that add the below code in the aspx file.
<%@ Page Language="vb" AutoEventWireup="false" CodeBehind="ValidatorDemo.aspx.vb"
Inherits="AllInOne.ValidatorDemo" %>
<!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 runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<table>
<tr>
<td>
Enter Name:
</td>
<td>
<asp:TextBox ID="txtName" runat="server"></asp:TextBox>
</td>
<td>
<asp:RequiredFieldValidator ControlToValidate="txtName" ErrorMessage="Name Required" SetFocusOnError="true"
runat="server"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td colspan="3">
<asp:Button runat="server" Text="Click Me!" />
</td>
</tr>
</table>
</div>
</form>
</body>
</html>
Explanation:
In the above code, the declarative sentence adds the required field validator:
<asp:RequiredFieldValidator ControlToValidate="txtName" ErrorMessage="Name Required" SetFocusOnError="true" runat="server"></asp:RequiredFieldValidator>I’m going to explain the each and every attribute in the above code. It’s a mandatory rule, that every asp.net control must start with “asp” tag.
Attribute
|
Description
|
runat
|
This is the server control, which is processed by the WEB Server (IIS). So this
is the required attribute for every server control.
|
Control ToValidate
|
This attribute is used to denote which control we need to validate. In this example, we give the ID of
the name text box “txtName”.
|
ErrorMessage
|
Used to give the Error message, when validation fails.
|
Happy Programming!!!
