Deleting a Subset of Session Variables
By Richard P.
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!
