Chapter 6 - Applying the User-Selected Themes

JohnB · July 20th, 2010, 11:38 AM

Hi,

I have just completed the Try It Out Exercise on page 231. However, when I view the Default.aspx page in the browser I receive the following error;

Server Error in '/Site' Application.
Theme 'Dark Grey' cannot be found in the application or global theme directories.
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.Web.HttpException: Theme 'Dark Grey' cannot be found in the application or global theme directories.

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:

[HttpException (0x80004005): Theme 'Dark Grey' cannot be found in the application or global theme directories.]
System.Web.Compilation.ThemeDirectoryCompiler.GetT hemeBuildResultType(String themeName) +934
System.Web.Compilation.ThemeDirectoryCompiler.GetT hemeBuildResultType(HttpContext context, String themeName) +73
System.Web.UI.Page.InitializeThemes() +8871714
System.Web.UI.Page.PerformPreInit() +38
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +328

Here is the code for my Frontend.master.vb

Partial Class MasterPages_Frontend
Inherits System.Web.UI.MasterPage

Protected Sub ThemeList_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ThemeList.SelectedIndexChanged
Dim preferredTheme As HttpCookie = New HttpCookie("PreferredTheme")
preferredTheme.Expires = DateTime.Now.AddMonths(3)
preferredTheme.Value = ThemeList.SelectedValue
Response.Cookies.Add(preferredTheme)
Response.Redirect(Request.Url.ToString())
End Sub

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not Page.IsPostBack Then
Dim selectedTheme As String = Page.Theme
Dim preferredTheme As HttpCookie = Request.Cookies.Get("PreferredTheme")
If preferredTheme IsNot Nothing Then
selectedTheme = preferredTheme.Value
End If
If Not String.IsNullOrEmpty(selectedTheme) AndAlso ThemeList.Items.FindByValue(selectedTheme) IsNot Nothing Then
ThemeList.Items.FindByValue(selectedTheme).Selecte d = True
End If
End If
End Sub

End Class

Here is the code for my BasePage.vb

Public Class BasePage
Inherits System.Web.UI.Page

Private Sub Page_PreInit(ByVal sender As Object, ByVal e As System.EventArgs) _
Handles Me.PreInit
Dim preferredTheme As HttpCookie = Request.Cookies.Get("PreferredTheme")
If preferredTheme IsNot Nothing Then
Page.Theme = preferredTheme.Value
End If
End Sub
Private Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender
If Me.Title = "Untitled Page" Or String.IsNullOrEmpty(Me.Title) Then
Throw New Exception("Page title cannot be ""Untitled Page"" or an empty string.")
End If
End Sub

End Class

Here is the code for my web.config page

<?xml version="1.0"?>



<configuration>
<system.web>
<pages theme="Monochrome" styleSheetTheme="Monochrome"></pages>
<compilation debug="false" strict="false" explicit="true" targetFramework="4.0" />
</system.web>

</configuration>

Thank you very much in advance!

Cheers

John B

Imar · July 20th, 2010, 12:14 PM

Hi there,

The theme is called DarkGrey and not Dark Grey with a space. Once you make that change, you may need to delete your cookies in order for the page to run successfully. Alternatively, check out page 18 for error handling tips.

Cheers,

Imar

JohnB · July 20th, 2010, 01:23 PM

Thank you for your quick reply Imar.

Clearing the browsers cookies has done the trick!

I am enjoying working through your book and find it clearly written and easy to follow as a newcomer to ASP.NET.

Cheers

JohnB

Imar · July 20th, 2010, 01:24 PM

That's good to hear!

Have fun with the rest of the book.

Cheers,

Imar

gfranco · December 7th, 2010, 05:36 PM

Hi there,

I just got this error on chapter 6 page 228.
When I was running the try out exercise.

Error 1 C:\Users\giofranc\Documents\Visual Studio 2010\WebSites\WebSite3\MasterPages\Frontend.master .vb(21): error BC30451: 'selectedTheme' is not declared. It may be inaccessible due to its protection level.

Code:

 
rotectedSub Page_Load(ByVal sender AsObject, ByVal e As System.EventArgs) HandlesMe.Load
IfNot Page.IsPostBack Then
Dim selectedTheme AsString = Page.Theme
Dim preferredTheme AsHttpCookie = Request.Cookies.Get("PreferredTheme")
If preferredTheme IsNotNothingThen
selectedTheme = preferredTheme.Value
EndIf
EndIf
IfNotString.IsNullOrEmpty(selectedTheme) AndAlso
ThemeList.Items.FindByValue(selectedTheme) IsNotNothingThen
ThemeList.Items.FindByValue(selectedTheme).selected = True
EndIf
EndSub

Imar · December 8th, 2010, 04:35 AM

Hi there,

You're closing off the first If statement too early. That way, the code that checks if selectedTheme is null or empty uses a variable which is defined in (and limited in scope to) an earlier If block and thus you get this error. If you look at the downloadable source for the book, you find the follow code in Frontend.master.vb:

Code:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
  If Not Page.IsPostBack Then
    Dim selectedTheme As String = Page.Theme
    Dim preferredTheme As HttpCookie = Request.Cookies.Get("PreferredTheme")
     If preferredTheme IsNot Nothing Then
      selectedTheme = preferredTheme.Value
    End If
    If Not String.IsNullOrEmpty(selectedTheme) AndAlso ThemeList.Items.FindByValue(selectedTheme) IsNot Nothing Then
      ThemeList.Items.FindByValue(selectedTheme).Selected = True
    End If
  End If
End Sub

Notice how the check for String.IsNullOrEmpty(selectedTheme) is still part of the outer If check for Page.IsPostBack.

Hope this helps,

Imar

gfranco · December 8th, 2010, 11:55 AM

I will check and I will let you know.

Cheers,
GF