This article will show you how to use Login control in ASP.Net applications. The article will not dig deep into advanced usage of this control or customization of this contro. I will discuss simple usage. I will be talking about advanced settings and usage in other articles.

Login control can use either MembershipProvider specified in web.config file, or can explicitly assign Membership provide or you can do custom authenication. To start with basics lets assume that you already have authentication methods implemented using your existing database and you want to leverage that infrastructure with Login control. So what you need to do is, add an handler for OnAuthenticate event handler for your control and authenticate user via that method.

Redirecting After Login

If authentication fails user stays on the same login page. On successful login the user gets redirected to appropriate page. There are couple of ways of specifying the page where user gets sent after successful authentication.

• A query string parameter ReturnUrl with a value of URL for redirection is one way. After authentication the implemnetation of Login control will look at this query string parameter and redirect the user to that URL.
• You can set DestinationPageurl property of the control and set the URL of target page in there.
• You can handle OnLoggedin event of the control and manually call Response.Redirect to targer page.

Following code snippets show what the attributes on page look like and how OnAuthenticate event handler sets Authenticated value in the event argument.

<asp:login id="ctlLogin" runat="server" onauthenticate="OnAuthenticate"
    onloggedin="OnLoggedIn" onloggingin="OnLoggingIn" destinationpageurl="~">
</asp:login>

protected void OnAuthenticate(object sender, AuthenticateEventArgs e)
{
    e.Authenticated = false;
    if (String.Compare(ctlLogin.UserName, "foo", true) == 0 &&
        String.Compare(ctlLogin.Password, "bar", false) == 0)
    {
        e.Authenticated = true;
    }
}		

protected void OnLoggedIn(object sender, EventArgs e)
{
    Response.Redirect("~");
}