When a user logs in, my code sets a Session variable using System.Web.HttpContext.Current.Session["customer_ref"], within HandleUserLogin().
I’m doing this in the following class, SessionManager:
SessionManager.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
/// <summary>
/// Summary description for Session
/// </summary>
public class SessionManager
{
public string customer_ref;
public bool logged_in = false;
public SessionManager()
{
//
// NULL REFERENCE EXCEPTION CAUSED HERE
//
//
// Check to see if the user is logged in (is a customer reference set?)
if (System.Web.HttpContext.Current.Session["customer_ref"] != null)
{
// The user is logged in
logged_in = true;
}
}
public bool HandleUserLogin(string username, string password)
{
if ((!string.IsNullOrEmpty(username)) && (!string.IsNullOrEmpty(password)))
{
// Check that the username and password are valid
if ((!string.IsNullOrEmpty(username)) && (password == "password"))
{
// Generate a new session ID
// TODO: Find out how to.
// Set the session variables
System.Web.HttpContext.Current.Session["customer_ref"] = username;
// Set the variables of this Session object for future use
this.customer_ref = username;
// Set the logged in status to true
this.logged_in = true;
return true;
}
else
{
// Username and password are incorrect
return false;
}
}
// The username or password was not entered
return false;
}
public void HandleUserLogout()
{
System.Web.HttpContext.Current.Session["customer_ref"] = null;
// Unset the variables in the SessionManager object
this.customer_ref = string.Empty;
// Set the logged in status to false
this.logged_in = false;
}
}
Once this Session variable is set, I am happily able to show it on the page using the following code and the value that I set it to appears nicely.
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" EnableSessionState="True" %>
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<%
//
// WRITE THE CUSTOMER REFERENCE FROM THE SESSION
//
Response.Write(System.Web.HttpContext.Current.Session["customer_ref"]);
%>
</body>
</html>
However, I am not able to access it from another page called dashboard.aspx as it throws a NullReferenceException when I call my SessionManager() class which tries to access the Session variable upon construction.
Here’s the code for dashboard.aspx, dashboard.aspx.cs:
dashboard.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="dashboard.aspx.cs" Inherits="dashboard" MasterPageFile="~/Design.master" EnableSessionState="True" %>
<asp:Content ID="customer" ContentPlaceHolderID="CustomerInfo" runat="server">
<div class="customer_name"><% Response.Write(customer.customer_name); %></div>
<div class="customer_account_number">Account number: <% Response.Write(customer.customer_ref); %></div>
</asp:Content>
<asp:Content ID="outstanding_orders" ContentPlaceHolderID="Content" runat="server">
<div class="content_left_title_wrapper">
<h2 class="content_left_title">Your Outstanding Orders</h2>
</div>
<table id="outstanding_orders" cellpadding="0" cellspacing="0">
<colgroup span="4"></colgroup>
<colgroup span="1" class="view_link_col"></colgroup>
<tr>
<th><div>Order Number</div></th>
<th><div>Date Placed</div></th>
<th><div>Total Cost</div></th>
<th><div>Order Status</div></th>
<th></th>
</tr>
<%
// Loop through all of the outstanding orders for the customer
foreach (OrderSummary order_item in outstanding_orders)
{
%>
<tr>
<td><div><% Response.Write(order_item.order_number); %></div></td>
<td><div><% Response.Write(order_item.uk_order_date); %></div></td>
<td><div>£<% Response.Write(order_item.order_total); %></div></td>
<td><div>Incomplete</div></td>
<td><div><a href="orderlines.aspx?orderno=<% Response.Write(order_item.order_number); %>" class="order_detail_link">Detail<br /><img src="images/design/view_order_arrow.png" /></a></div></td>
</tr>
<%
}
%>
</table>
</asp:Content>
dashboard.aspx.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using IBMU2.UODOTNET;
using System.Xml.Linq;
public partial class dashboard : System.Web.UI.Page
{
// Get the users session
SessionManager session = new SessionManager();
// Create a new connection to the database
ReflexDatabase db_con = new ReflexDatabase();
// Blank list to hold the orders
public List<OrderSummary> outstanding_orders = new List<OrderSummary>();
public XDocument test { get; set; }
public Customer customer;
// OnInit is called before the page loads (See internet for ASP.NET Page Lifecycle)
protected override void OnInit(EventArgs e)
{
if (session.logged_in == false)
{
// I've tried it here, and it won't redirect
Response.Redirect("default.aspx");
}
}
protected void Page_Load(object sender, EventArgs e)
{
try
{
// Create the customer as a Customer object
customer = new Customer(session.customer_ref);
// Query the TOELINE database
XDocument customer_orders = db_con.Query(String.Format("LIST TOEHEAD BY.DSND ORDERNO WITH CUSREF = \"{0}\" AND ORDERSTATUS < 50 ORDERNO DATEONFILE T.VAL.TO.INV ORDERSTATUS TOXML ELEMENTS", customer.customer_ref));
test = customer_orders;
// Use LINQ to pipe the data in to OrderSummary objects
var linqQuery = from n in customer_orders.Element("ROOT").Descendants("TOEHEAD")
select new OrderSummary
{
//order_number = n.Element("ORDERNO").Nodes()..ToString(),
order_number = n.Descendants("ORDERNO").First().Value,
us_order_date = n.Descendants("DATEONFILE").First().Value,
order_total = n.Descendants("T.VAL.TO.INV").First().Value
};
// Add all of the items to the list of orders outstanding for the customer
foreach (OrderSummary linqItem in linqQuery)
{
outstanding_orders.Add(linqItem);
}
}
finally
{
// Close the session to prevent hogging of sessions
db_con.CloseSession();
}
}
}
You have made the
SessionManageran instance member of thePage. That means the initializer will run (I think) just before the Page constructor is run by the Page handler.And that happens before the
Sessionhas been added to the HttpContext object.Try changing this line:
to
And then new it up in (for instance) the OnInit method (also, don’t forget to call
base.OnInit()):If this is going to be your authentication scheme, you might wan’t to create custom BasePage type which your other pages could derive from. That way you don’t have to copy the same pieces of code to all pages that require the user to be logged in.
Or (as I already wrote in an answer to a previous quetion of yours) you could just go ahead and implement the authentication using a custom MembershipProvider and let the framework handle all the plumbing.