Custom Membership, Role Providers, Website administration tool, and Role based access to individual files

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class Admin_Users_edit_user : System.Web.UI.Page
{
    MembershipUser user;
    string username;

    

    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void Page_PreRender(object sender, EventArgs e)
    {
        UserRoles.DataSource = Roles.GetAllRoles();
        UserRoles.DataBind();

    }

    protected void UserInfo_ItemUpdating(object sender, DetailsViewUpdateEventArgs e)
    {
        //Need to handle the update manually because MembershipUser does not have a
        //parameterless constructor  

        user.Email = (string)e.NewValues[0];
        user.Comment = (string)e.NewValues[1];
        user.IsApproved = (bool)e.NewValues[2];

        try
        {
            // Update user info:
            Membership.UpdateUser(user);

            // Update user roles:
            UpdateUserRoles();

            UserUpdateMessage.Text = "Update Successful.";

            e.Cancel = true;
            UserInfo.ChangeMode(DetailsViewMode.ReadOnly);
        }
        catch (Exception ex)
        {
            UserUpdateMessage.Text = "Update Failed: " + ex.Message;

            e.Cancel = true;
            UserInfo.ChangeMode(DetailsViewMode.ReadOnly);
        }
    }

    private void UpdateUserRoles()
    {
        foreach (ListItem rolebox in UserRoles.Items)
        {
            if (rolebox.Selected)
            {
                if (!Roles.IsUserInRole(username, rolebox.Text))
                {
                    Roles.AddUserToRole(username, rolebox.Text);
                }
            }
            else
            {
                if (Roles.IsUserInRole(username, rolebox.Text))
                {
                    Roles.RemoveUserFromRole(username, rolebox.Text);
                }
            }
        }
    }


    protected void goBack(object sender, EventArgs e)
    {
        Response.Redirect("~/Admin/Users/Default.aspx");
    }
}