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FormsAuthentication.RedirectToLoginPage Method (String)

Redirects the browser to the login URL with the specified query string.

Namespace:  System.Web.Security
Assembly:  System.Web (in System.Web.dll)

public static void RedirectToLoginPage(
	string extraQueryString
)

Parameters

extraQueryString
Type: System.String

The query string to include with the redirect URL.

The RedirectToLoginPage method redirects the browser to the LoginUrl and includes the extraQueryString value as the QueryString for the redirected URL.

The RedirectToLoginPage method does not clear the forms-authentication cookie. You can use the RedirectToLoginPage method in conjunction with the SignOut method to log one user out and allow a different user to log in.

The following code example clears the forms-authentication cookie using the SignOut method and redirects the user to the login page using the RedirectToLoginPage method.

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Web.Security" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

public void LoginLink_OnClick(object sender, EventArgs args)
{
  FormsAuthentication.SignOut();
  FormsAuthentication.RedirectToLoginPage(GetQueryString());
}

private string GetQueryString()
{
  string queryString = "";

  NameValueCollection qs = Request.QueryString;

  foreach (string key in qs.AllKeys)
    foreach (string value in qs.GetValues(key))
      queryString += Server.UrlEncode(key) + "=" + Server.UrlEncode(value) + "&";

  return queryString.TrimEnd('&');    
}

</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
<form id="form1" runat="server">
Welcome <b><%=User.Identity.Name%></b>. Not <b><%=User.Identity.Name%></b>? 
Click <asp:LinkButton id="LoginLink" Text="here" 
                      OnClick="LoginLink_OnClick" runat="server" />
to sign in.

<!-- Page Contents -->

</form>



</body>
</html>

.NET Framework

Supported in: 4.6, 4, 3.5, 3.0, 2.0

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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