By Richard P.

To Delete a Specific Session Variable...

This tip demonstrates how to remove a set of Session variables that begin with a particular substring. If you want to learn how to delete a specific Session variable be sure to read the FAQ: "How can I kill one session variable at a time? I don't want to have to abandon the whole session, just kill off a few session variables that were used?" If you want to remove all of the Session variables, use Session.Contents.RemoveAll().

When using Sessions to store variables in, I use a naming convention - for example, for all Customer related info I prefix the session variable with the substring Customer. (so for the CustomerID it would be Customer.ID, the customer username would be Customer.Name, etc.) This is very useful when viewing the session objects as you can see the related objects straight off.

The problem I had the other day was that I wanted to remove only those items from the Session which were prefixed SW.. So first off I used the following code:

'--------------------------------------- Session("SW.1")="Test 1" Session("SW.2")="Test 2" Session("Other")="Other" For Each SessionItem in Session.Contents If Left(SessionItem,3) = "SW." then Session.Contents.Remove(SessionItem) end if Next '---------------------------------------

This seems fine, but when it's run, what happens is that SW.1 is removed, but SW.2 is NOT removed. Why? I'm not exactly sure, but I guess that the index is then reset so that SW.2 is now where SW.1 was, and seeing as we have iterated past that item in the For Each...Next statement, the loop just moves to Other, missing out SW.2 altogether! Eek!

So to get round this I wrote the following function, which will properly delete all Session variables that begin with a specified substring:

'--------------------------------------- function SessionRemoveSelected(sItemPrefix) '///////////////////////////////////////////////// ' Remove Selected Items starting with sItemPrefix ' from the Session. e.g. SS. will remove SS.ID and ' SS.NAME but not CustomerID Returns True or False ' depending on whether any items where removed. '--------------------------------------- ' sItemPrefix [string] : Item Prefix '///////////////////////////////////////////////// dim arySession() dim lCount, lPrefixLength dim SessionItem dim blnResult lCount = -1 lPrefixLength = len(sItemPrefix) blnResult = false ' temporarily store in array items to remove For Each SessionItem in Session.Contents if left(SessionItem,lPrefixLength) = sItemPrefix then lCount = lCount + 1 redim preserve arySession(lCount) arySession(lCount) = SessionItem end if Next ' remove items if IsArray(arySession)and lCount >= 0 then for lCount = LBound(arySession) to UBound(arySession) Session.Contents.Remove(arySession(lCount)) next blnResult=true end if SessionRemoveSelected = blnResult end function '-------------------------------------------------

This now saves me a lot of time. I hope this can be of use to someone else!

Happy Programming!

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