CustomValidator for login page : CustomValidator « Validation « ASP.NET Tutorial
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<title>CustomValidator Control Sample</title>
<script runat="server" language="C#">
void CheckUniqueUserName(Object s, ServerValidateEventArgs e)
{
string username = e.Value.ToLower();
if(username == "user" || username == "password")
{
e.IsValid = false;
}
}
void submitButton_Click(Object s, EventArgs e)
{
if(Page.IsValid)
{
submitButton.Text = "Valid";
}
else
{
submitButton.Text = "Invalid!";
}
}
</script>
</head>
<body>
<form runat="server">
New Username:<br />
<asp:TextBox ID="usernameTextBox" runat="server" />
<asp:CustomValidator ID="usernameUnique" runat="server"
ControlToValidate="usernameTextBox"
OnServerValidate="CheckUniqueUserName"
ErrorMessage="This username already taken!" />
<asp:Button ID="submitButton" runat="server"
OnClick="submitButton_Click" Text="Submit" />
</form>
</body>
</html>