obtain current logged in user - asp.net

Question

I'm using Activedirectory as membership provider. I want to store the current logged in user in a session.
protected void user_login_LoggedIn(object sender, EventArgs e)
{
MembershipUser user = Membership.GetUser();
}
the code above gives the error below
The parameter 'username' must not be empty.
Parameter name: username
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details:
System.ArgumentException: The parameter 'username' must not be empty.
Parameter name: username
Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Stack Trace:
[ArgumentException: The parameter 'username' must not be empty.
Parameter name: username]
System.Web.Util.SecUtility.CheckParameter(String& param, Boolean checkForNull, Boolean checkIfEmpty, Boolean checkForCommas, Int32 maxSize, String paramName) +1976411
System.Web.Security.ActiveDirectoryMembershipProvider.CheckUserName(String& username, Int32 maxSize, String paramName) +30
System.Web.Security.ActiveDirectoryMembershipProvider.GetUser(String username, Boolean userIsOnline) +86
System.Web.Security.Membership.GetUser(String username, Boolean userIsOnline) +82
System.Web.Security.Membership.GetUser() +19
darts.login.user_login_LoggedIn(Object sender, EventArgs e) in E:\Projects\DARTS\source\darts\darts\login.aspx.cs:24
System.Web.UI.WebControls.Login.OnLoggedIn(EventArgs e) +111
System.Web.UI.WebControls.Login.AttemptLogin() +179
System.Web.UI.WebControls.Login.OnBubbleEvent(Object source, EventArgs e) +101
System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
System.Web.UI.WebControls.Button.OnCommand(CommandEventArgs e) +118
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +166
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565
Version Information: Microsoft .NET Framework Version:2.0.50727.4211; ASP

Answer 1

Edit:
Based upon using this from ASP.NET to get the login information about the currently authenticated user, I see a couple ways that this might work. First, if you are using Forms authentication with the Active Directory membership provider, you could capture the username there. Then you just put the username inside of the GetUser() method like so: GetUser(yourUser) and you should get the information needed.
If this isn't an option, I believe the username information is stored under your login control (in your case, I believe the name is user_login if you are indeed using a login control). You would simply say user_login.username and put that inside the GetUser() method.
Finally, you could try the old fallback of HttpContext.Current.User.Identity.Name and put that inside of your GetUser() method.