Cookie question

janilane · May 4th, 2009, 09:59 PM

Hi,

In the code, you put the creation of cookie in the dropdownlistbox and it is working fine if the cookie is already present. I tried expiring the cookie, and re-running the app again, and so it crashes. The page_load event in the master page is getting the theme, and the Select Case is converting a null value in to lower case.

What will happen if the web app is run for the first time without the cookie stored in the user pc, nor any theme defined in web.config?

Thanks

Imar · May 5th, 2009, 03:53 AM

Hi there,

I am not sure what the problem is. Take a look at the code in the Master Page:

Code:

HttpCookie preferredTheme = Request.Cookies.Get("PreferredTheme");
if (preferredTheme != null)
{
  selectedTheme = preferredTheme.Value;
}

This uses some defensive coding and only fires when the cookie is there and not null. Otherwise, preferredTheme keeps its default value of Page.Theme.

If that doesn't help, can you provide detailed steps on reproducing this problem?

Imar

janilane · May 5th, 2009, 04:58 PM

Hi Imar,

What I did:

1.In the code-behind of Master page SelectedIndexChanged, I set the cookie expiry value to -1 just to expire it. Ran the application, and select value from the list box. As expected it will throw an error but that's okay as I just want to expire the cookie;

preferredTheme.Expires = DateTime.Now.AddMonths(-1)

2.Set the cookie value again to 3 months (because I'm thinking of the scenario where this is the first time the application will run without any cookie in the machine) like this;

preferredTheme.Expires = DateTime.Now.AddMonths(3)

3. Removed any theme set in the web.config file, and ran the app. It threw an error. I guess because the app still depends on a DEFAULT theme even if the user has not selected any themes in the dropdown list when the app is run for the first time.

Nevermind this scenario, just experimenting with code...

Thanks again.

Imar · May 6th, 2009, 03:35 PM

Hi janilane,

I don't think it's related to the cookie but to this:

Quote:

Removed any theme set in the web.config file

The application assumes that a theme is configured in the web.config. This is always the default theme, which can be overridden by the user. Without a least a default theme, the site looks pretty ugly.

If you do want to proceed with this, you need to wrap the code that tries to find the item in the list and that sets the correct navigation items in another if statement:

Code:

if (selectedTheme != null)
{
  if (lstPreferredTheme.Items.FindByValue(selectedTheme) != null)
  {
    lstPreferredTheme.Items.FindByValue(selectedTheme).Selected = true;
  }
  switch (Page.Theme.ToLower())
  {
    case "darkgrey":
      Menu1.Visible = false;
      TreeView1.Visible = true;
      break;
    default:
      Menu1.Visible = true;
      TreeView1.Visible = false;
      break;
  }
}

Depending on what you want to do with the navigation in a "themeless page", you may need to change the logic about hiding or showing the Menu or the TreeView.

Hope this clarifies things a bit...

Imar

kiwibrit · November 2nd, 2009, 06:19 PM

FWIW, I had a similar problem to the original poster. I am building a site using structural concepts from this book - in my case allowing switching between several themes so that others can give opinions on the best one for a company site under development. I too could not figure why I had no default theme. For anybody searching this forum like me with the same problem, Imar's answer gives the clue. If you go to web.config, there is a default theme set

Code:

<pages theme="Monochrome">

Now I am sure this must have been covered in the book - but I had forgotten. Hope I am not stating the obvious - but I was floundering a bit on this one, so maybe it will help someone else.

Imar · November 3rd, 2009, 01:37 PM

The book tells you to add and remove the theme at several different stages to see different behavior. I am not sure what the last action is: add or remove.

I am currently working on v4 of this book and about to start with the chapter on themes, so if anything comes up that clarifies this behavior, I'll post here with an update.

Cheers,

Imar

kiwibrit · November 4th, 2009, 07:52 AM

Another point on this one. When developing the site on your own computer, the cookie set is for localhost, and it looks for PreferredTheme. If you are working on any other site's development with a similar structure (BasePage with similar cookie request) make sure you clear that cookie first. Otherwise, for your new site, the browser will still be looking at localhost, will look for the cookie, look for the preferred theme you declared on the book's site, not find it, and throw an error.

A bit unusual maybe - but it flumoxed me for a few minutes.

Imar · November 5th, 2009, 04:18 AM

Yeah, good tip. On production servers this is not a problem as cookies are scoped to a domain. However, as you point out, multiple sites running on localhost will share cookies.

You could prefix your cookie keys with a unique name, like PW_ (for Planet Wrox). But then you need to remember to change that when you copy content from one site to another ;-)

Cheers,

Imar