Chapter 6

elbkhm · February 10th, 2015, 06:32 PM

I've been working through the book, and I've hit a snag in the Try It Out on page 226 "Letting the User Select a Theme".

My cookie doesn't seem to be created. I can load the page, and select the theme from the drop down, which causes the refresh. But if I re-open the page from another tab, or close the browser and re-open it, it defaults back to Monochrome.

I've tried in both Chrome and IE, on both my home computer, and work computer. I don't see anything in my cookie settings that would cause it to be blocked.

I've done some searching on the issue, and I've seen some posts that suggest that cookies will not work if you are loading a page from http://localhost, which suggest using 127.0.0.1 instead, or setting up something in the hosts file, but 127.0.0.1 won't load the page for me (comes back with a "Bad Request - Invalid Host Name").

I also can't seem to change the the site URL in Visual Studio, possibly because I'm using Visual Studio Express. If I could do that, I might be able to get 127.0.0.1 working, which might let the cookies work. As it is, I'm not sure how to progress from here.

Any suggestions?

Imar · February 11th, 2015, 06:44 AM

Hi there,

Can you post the code for your page and code behind? Also, if you already added code to apply the theme, can you post that too?

Cheers,

Imar

elbkhm · February 11th, 2015, 12:45 PM

Frontend.master

Code:

<%@ Master Language="C#" AutoEventWireup="true" CodeFile="Frontend.master.cs" Inherits="MasterPages_Frontend" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <asp:ContentPlaceHolder id="head" runat="server">
    </asp:ContentPlaceHolder>
    <script src="/Scripts/modernizr-2.7.2.js"></script>
</head>
<body>
    <form id="form1" runat="server">
      <div id="PageWrapper">
        <header><a href="/"></a></header>
        <nav>Menu Goes Here</nav>
        <section id="MainContent">
          <asp:ContentPlaceHolder ID="cpMainContent" runat="server">
          </asp:ContentPlaceHolder>
        </section>
        <aside id="Sidebar">
          Select a Theme <br />
          <asp:DropDownList ID="ThemeList" runat="server" AutoPostBack="True">
            <asp:ListItem>Monochrome</asp:ListItem>
            <asp:ListItem>DarkGrey</asp:ListItem>
          </asp:DropDownList>
        </aside>
        <footer>Footer Goes Here</footer>
      </div>
    </form>
</body>
</html>

Frontend.master.cs

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class MasterPages_Frontend : System.Web.UI.MasterPage
{
    protected void Page_Load(object sender, EventArgs e)
    {
      if (!Page.IsPostBack)
      {
        string selectedTheme = Page.Theme;
        HttpCookie preferredTheme = Request.Cookies.Get("PreferredTheme");
        if (preferredTheme != null)
        {
          selectedTheme = preferredTheme.Value;
        }
        if (!string.IsNullOrEmpty(selectedTheme))
        {
          ListItem item = ThemeList.Items.FindByValue(selectedTheme);
          if (item != null)
          {
            item.Selected = true;
          }
        }
      }
    }
    protected void ThemeList_SelectedIndexChanged(object sender, EventArgs e)
    {
      HttpCookie preferredTheme = new HttpCookie("PreferredTheme");
      preferredTheme.Expires = DateTime.Now.AddMonths(3);
      preferredTheme.Value = ThemeList.SelectedValue;
      Response.Cookies.Add(preferredTheme);
      Response.Redirect(Request.Url.ToString());
    }
}

I haven't added the code to apply the theme yet.

Imar · February 14th, 2015, 03:41 PM

Hi there,

Your drop down is missing the following code:

OnSelectedIndexChanged="ThemeList_SelectedIndexCha nged"

That way, the code to set the cookie is never set.

Hope this helps,

Imar

elbkhm · February 17th, 2015, 12:33 PM

Awesome, that was the issue. :)

Thank you very much for your help Imar!