How to enable - disable caching programmatically and on-demand

Sometimes, when you're doing something programmatically, like moving tabs around, you really don't want caching in your way in any form, since there's a great danger it'll affect the outcome. For some reason, programmatically clearing the cache may not be enough - you just don't need any caching around when you do certain stuff, and you don't want to oblige any host user to manually clear the cache. Here's a really simple way to disable caching programmatically.

 

 

'Get the initial caching level
'from the HostSettings arraylist 
'(this is the easiest way)
Dim initialCachingLevel As String
initialCachingLevel = _
    HostSettings.Item("PerformanceSetting").ToString

'Disable caching
Dim hc As New Entities.Host.HostSettingsController
hc.UpdateHostSetting("PerformanceSetting", "0")

'Do your stuff here

'Enable caching with
'the initial caching level
hc.UpdateHostSetting("PerformanceSetting", initialCachingLevel)

 

What I'm doing in the bit of code above is disable caching temporarily to do what I have to do, then return it to its previous state. That's equivalent to going to Host Settings-Performance, from the Host menu, change the caching level, click "update", do any job I have to do and then get back to the Host menu and return caching to its previous value.

 

The caching level is defined by the "PerformanceSetting" Host property which can take string values ranged from "0" to "3" representing different levels of caching:

 

0 - No caching

1 - Light caching

2 - Moderate caching

3 - Heavy caching

 

Some notes:

 

You can get the current caching level from the HostSettingsController too, but it's a bit more fussy since the GetHostSetting method returns an IDataReader. Since the Host's settings get copied to the publicly-available HostSettings hashtable, I thought it's easier to obtain the current setting from there.

 

Changing the value in the HostSettings hashtable will NOT affect your caching. You've got to use HostSettingsController.UpdateHostSetting.

 

You may also want to clear any cache left before you start doing your stuff, it helps in some cases. In this case, the DataCache class may prove very useful. Here's what you can do (you can choose not to execute some of these lines, depending on your needs):

 

DataCache.ClearTabsCache(0)
DataCache.ClearPortalCache(0, True)
DataCache.ClearHostCache(True)
DataCache.ClearModuleCache()
DataCache.ClearTabPermissionsCache(0)
DataCache.ClearUserCache( _
        0, _
        UserController.GetCurrentUserInfo().Username)

 

 

Some of the above statements may overlap, in the sense that they're actually subsets of other statements. For example, ClearHostCache() is considered equivalent to the Clear Cache option that exists in the Host Settings page. I personally prefer to issue ALL those statements, even if they overlap.

 

The DataCache class has some more methods but I think those mentioned here are enough to give you a good start. You'll probably find out the rest yourself, in an as-needed basis.

 

The above code applies only to portal 0. Whenever you see a boolean parameter there, it's indicating "cascade" cache clearing, which I always want set to true. Also, the ClearUserCache() method needs the currently logged on user's name, which I get by using UserController.GetCurrentUserInfo() which returns a UserInfo object containing, among others, the user's name.

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Resolving "fileid=xxx" field values to actual file paths

Following a previous article of mine, The dbo.tabs.IconFile field issue, I would like to share an easy way to resolve any field that holds values of the type "FileID=xxx" (where xxx is the primary key of a record in the Files table) into the actual file path. This is especially useful when you deal with the IconFile field in the Tabs table, as well as with fields of type Image in a User Defined Table, and probably in a lot more places too.

 

I have created a UDF (User Defined Function) which accepts a string value and looks whether it's of type "FileID=xxx". If it is, it constructs the full path (including the portal number) and returns that, otherwise it just returns the initial string with no modification at all. You can use this scalar-valued function inline, in your own SELECT statements, like this:

 

EXAMPLE

SELECT 
tabid, 
tabname, 
dbo.ResolveFileField(iconfile) 
FROM tabs 

 

CODE

CREATE FUNCTION 
dbo.ResolveFileField
(
    @file varchar(1000)
)
RETURNS varchar(1000)
AS
BEGIN
    
declare @retval varchar(1000)
declare @portalid int

if patindex ('FileID=%', @file) >0

begin

    declare @fileid int
    set @fileid = 
        convert(
                int, 
                replace
                    (
                    @file
                    , 'fileid='
                    , ''
                    )
                )   

    select 
        @retval = 
            'Portals/' 
            + convert
                    (
                      varchar(10)
                    , files.portalid
                    ) 
            + '/' 
            + folders.folderpath 
            + files.filename 
    from 
        files
    left outer join folders
    on files.folderid = folders.folderid
    where 
        files.fileid=@fileid
    
end

else

begin
    set @retval = @file
end

return @retval

END
GO

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How to promote a regular DotNetNuke user to a superuser

I found this in Kevin Southworth's blog and I think it's worth mentioning since it may save your life in case you have forgotten your superuser's password. Using SQL, you can promote a regular DNN user to a superuser like this:

 

-- Promote regular user to SuperUser

DECLARE @username varchar(50)

SET @username = 'theUsernameToPromote'

UPDATE 
    Users 
SET 
    IsSuperUser = 1 
WHERE 
    username = @username

DELETE FROM 
    UserPortals 
WHERE 
    UserId = 
    (SELECT UserID 
    FROM Users 
    WHERE username = @username)

 

Simply replace 'theUsernameToPromote' with the user name you need.

 

Thanks Kevin!

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Persisting large values in Module Settings when creating a custom module

So you want to create a simple custom module. At first, it seems easy. Just two or three settings to take care of, no need for complicated, custom tables and unistall/uninstall scripts. DNN's built-in module settings API seems to be enough. But suddenly, needs grow a lot. There are some large values you need to store and the ModuleSettings table won't allow large chunks of information per row. It seems that you have to switch to a custom table which will be holding your settings...

 
...or use my class :)

 

I came upon the need of storing just one large value (a serialized object, to be more specific) in a custom module I was creating. I didn't have any way to know how large the serialized (XML) sting would be, since the object was a collection, and I HAD to store it in module settings. I thought it wouldn't be worth to create a custom table and the accompanying code to store settings in a case like this, so I decided to extend DNN's ModuleController class instead.

What I did was to write a new ModuleControllerExtended class which inherits from ModuleController (so I could use it in its place) and add two methods to it:

1. UpdateLargeTabModuleSetting: This method is essentially an extension of the UpdateTabModuleSetting method of the ModuleController class which allows storing large string values in the ModuleSettings table by breaking them into smaller chunks and storing multiple name/value pairs. If a value is small enough to fit into a single row of the ModuleSettings table, then it's stored normally, as it would with the UpdateTabModuleSetting method.

When the value is large, it's stored in 2KB chunks in several rows using a numeric prefix (in the form of _x) for each row, based on the initial name given for the setting. For example, a setting named "SerializedObject" with a value sized at 5KB would be stored in 3 rows with names "SerializedObject_0", "SerializedObject_1" and "SerializedObject_2" accordingly.

The method also takes care to delete rows from the ModuleSettings table every time an update takes place to ensure that there are no leftovers should you specify a value of a smaller size (and probably fewer chunks) than the one that may be already stored.

 

2. ReadLargeTabModuleSetting: This one reads a large setting doing all the work needed to give you back its string value, but it can also read single-row settings. This is a shared method, and it was added to the class only for consistency. It does not extend any of the known methods of the ModuleController class, meaning you can always remove it from the definition of the class and use it as stand-alone code.

 

To use the method, you will need the hashtable containing the module's settings, which you can easily get by using the base class GetModuleSettings() method. You feed the method with the hashtable, the module's id and the name of the setting you want and you get a string value containing the "large" value for the setting you specified, or just a setting value should the setting be a "normal" one.

 

It's not really complicated and it should save you a lot of time when dealing with situations like the one I described above. I would love to hear your comments, though.

 

Here's the code:

 

Imports Microsoft.VisualBasic
Imports System.Collections.Generic

Public Class ModuleControllerExtended
    Inherits DotNetNuke.Entities.Modules.ModuleController

Public Sub New()
    MyBase.new()
End Sub

Public Sub UpdateLargeTabModuleSetting( _
   ByVal tabModuleSettings As Hashtable _
  , ByVal tabModuleID As Int32 _
  , ByVal settingName As String _
  , ByVal settingValue As String)

    Dim cntDel As Int32 = 0
    Dim o As Object
    Dim continueDeleting As Boolean
    continueDeleting = True

    'Delete all multiple-value module settings, if they exist. 
    While continueDeleting = True
        o = tabModuleSettings(settingName + "_" + cntDel.ToString)
        If Not o Is Nothing Then
            DeleteTabModuleSetting(tabModuleID, settingName + "_" + cntDel.ToString)
            cntDel += 1
        Else
            continueDeleting = False
        End If
    End While

    'Guard - if setting value is less than 2KB, update normally and exit 
    If settingValue.Length < 2000 Then
        'Normal value 
        UpdateTabModuleSetting(tabModuleID, settingName, settingValue)
        Exit Sub
    End If

    'If we get to this point, then setting value is more than 2KB. 
    'Delete the original setting (if it exists) so as not to get confused. 
    DeleteTabModuleSetting(tabModuleID, settingName)


    'Split the value in 2KB chunks 
    Dim stringList As New List(Of String)
    Dim sb As New StringBuilder(settingValue)

    While sb.Length >= 2000
        stringList.Add(sb.ToString.Substring(0, 1999))
        sb.Remove(0, 1999)
    End While

    'Add the last chunk 
    If sb.Length > 0 Then stringList.Add(sb.ToString)

    'Now do the update changing the setting name with the suffix _x (x=0,1,2,etc.) for 
    'each update 
    Dim cnt As Int32 = 0
    For Each s As String In stringList
        UpdateTabModuleSetting(tabModuleID, settingName + "_" + cnt.ToString, s)
        cnt += 1
    Next

End Sub

Public Shared Function ReadLargeTabModuleSetting( _
     ByVal tabModuleSettings As Hashtable _
    , ByVal tabModuleID As Int32 _
    , ByVal settingName As String) As String

    'Guard - if there is a single setting, just return that and exit 
    Dim objTester As Object
    objTester = tabModuleSettings(settingName)
    If Not objTester Is Nothing Then
        Return (CType(objTester, String))
    End If

    'If we got to this point, there's a large value stored. 
    'Loop through the records and reconstruct the value. 
    Dim sb As New StringBuilder
    Dim cnt As Int32 = 0
    Dim o As Object
    Dim continueAdding As Boolean
    continueAdding = True

    While continueAdding = True
        o = tabModuleSettings(settingName + "_" + cnt.ToString)
        If Not o Is Nothing Then
            sb.Append(CType(o, String))
            cnt += 1
        Else
            continueAdding = False
        End If
    End While

    Return sb.ToString

End Function

End Class

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Creating pages based on templates - eventually!

All my attempts to use custom templates when creating new DNN pages for my portals were frustrating. Even though I exported the template from a page using the Export feature, the new template would not show up at all in the combo box when creating a new page, although it existed in the file system. Even the default template wouldn't show up!

Here's a simple solution to make those template files appear when you create a new page:

1. Go to Host Settings - Other Settings and locate the "File Upload Extensions" section. Add "template" (without the quotes) there and save your changes.

2. Click "Restart Application" in Host Settings.

3. Go to the File Manager and synchronize files with the "recursive" option set.

4. Optionally, clear the portal's cache in Host Settings (only if it doesn't seem to work differently).

Now you'll have access to your custom templates when creating new pages. Hope that helps.

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Adding Javascript to the BODY tag in DNN

When working with .ascx skin files, you will sometimes need to add some Javascript to the BODY tag, such as something that runs when the OnLoad event triggers.

Well, you can always add a BODY tag inside your .ascx file along with the Javascript you like and hope that the browser will understand that. Essentially, you'll end up having two BODY tags in your source code-one that is generated by DNN and one that is typed by you. Some browsers (like Chrome) understand what's happening and try to transfer the Javascript to the actual BODY tag when rendering the page, but others don't.

What you can do, though, is create a Page_Init event handler inside your .ascx file and put this code there:

Dim body As System.Web.UI.HtmlControls.HtmlGenericControl = CType(Page.FindControl("body"), System.Web.UI.HtmlControls.HtmlGenericControl) 
body.Attributes("onload") = "blablablaJavascript"

Where blablablaJavascript is your Javascript. Of course, you can do that for other events (even for other tags) as well.

If you're using a single .ascx file with no code-behind (like most do), you'll want to define a Page_Init event there. You can do that like this:

<script runat="server">

  Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init 

'Add your code here

    End Sub 

</script>

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Thickbox and Google Maps API - avoiding random thickbox initialization problems

Thickbox is a very nice JQuery-based Javascript plugin that allows you to present images and other stuff (even whole pages!) in your page in a popup manner but without leaving the current page or opening a new one. Essentially, it's considered an evolution of the Lightbox script which only works with images.

Many developers use Thickbox with Google maps, in order to provide clickable links on Google Map bubbles that lead to enlarged photos or other info. Some of them (including me) noticed, to their surprise, that suddenly Thickbox wouldn't work correctly inside Google Maps. Specifically, it would work once in a while, and the only way to ensure it worked would be to click on a bubble, close it an then click on another. Then all Thickbox links inside bubbles would work.

There seems to be a problem with the new version of the Google Maps API that kills the functionality of Thickbox. According to this discussion on Google Groups, a way to ensure Thickbox is working correctly is to "lock" on version 2.122 of the Google Maps API inside the Javascript that creates the markers. That is, use: google.load("maps", "2.122"); instead of google.load("maps", "2.x");

I've been using Thickbox and Google Maps in some DNN sites and I was panicked to see this happening in the first place. Although this post is not exactly DNN-related, I think it'll be useful to all of you working with DNN out there. I was very happy to know that there wasn't anything wrong with my DNN development, it was only Google's API.

Hope it helps.

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