VBA – Processing ICS calendar file attachments
This article brings to conclusion the Outlook VBA macro/script I wrote to process event scheduling attachments (.ICS or ICalendar files). The first article shows how to process emails and remove their associated attachments. The second shows how to open the files and both read the file contents into an array as well as write (append) to the file. This code works in Outlook 2007.
The script does the following:
1. Check if the email has an attachment
2. If the attachment is an ICalendar (.ICS) file, remove it to a common folder and update the email with a link to the detached file.
3. Loop through the ICS files in the designated folder and load them into an array.
4. If the last element in the array contains the value “PROCESSED”, skip it
5. Take the UID (Unique IDentifier) array element and turn it into an Outlook Event GUID.
6. Check if there are any events which have the UID Guid. If there are, this indicates the new file is an update to a previously processed event.
7. If there is no previous event with the UID Guid, add the event using the UID Guid as an identifier.
8. If there is a previous event and the new notice is a cancellation, delete the event.
9. If there is a previous event and the new notice is not a cancellation, update the event.
10. Append a line to the ICS file with the value “PROCESSED”.
Public Sub SaveICSAttachmentsMacro()
Dim objOL As Outlook.Application
Dim objitem As Outlook.MailItem 'Object
Dim objAttachments As Outlook.Attachments
Dim objSelection As Outlook.Selection
Dim i As Long
Dim lngCount As Long
Dim strFile As String
Dim strFolderpath As String
Dim strDeletedFiles As String
Dim strArray() As String
Dim ac As Long
Dim lSeq As Long
Dim lPriority As Long
Dim strLine As String
Dim strField As String
Dim strValue As String
Dim strMethod As String
Dim strUid As String
Dim strSummary As String
Dim strLocation As String
Dim strDesc As String
Dim strOrganizer As String
Dim strDate As String
Dim dtStart As Date
Dim dtEnd As Date
Dim hexUID
' Instantiate an Outlook Application object.
Set objOL = Application
Dim objNs As Outlook.NameSpace
Set objNs = objOL.Session
Dim objFolder As Outlook.MAPIFolder
Set objFolder = objNs.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderCalendar)
Dim objAppts As Outlook.Items
Set objAppts = objFolder.Items
Dim objAppt As Outlook.AppointmentItem
Dim strFilter As String
' Get the path to your My Documents folder
strFolderpath = CreateObject("WScript.Shell").SpecialFolders(16)
On Error Resume Next
' Get the collection of selected objects.
Set objSelection = objOL.ActiveExplorer.Selection
''''''''''''''''''''
'[snip] see code from Removing attachments post
'''''''''''''''''''
' call function in different module
' this populates the string array from the iCalendar file
icsFileToArray strFile, strArray
' check last element of array to determine if file previously processed
If strArray(UBound(strArray)) = "PROCESSED" Then
'file already processed
GoTo ExitSub
Else
' loop through array to process event
For ac = 1 To UBound(strArray)
' separate data pairs
strLine = strArray(ac)
If InStr(1, strLine, ":") > 0 Then
strField = Mid(strLine, 1, InStr(1, strLine, ":") - 1)
strValue = Mid(strLine, InStr(1, strLine, ":") + 1)
End If
Select Case strField
Case "METHOD"
' REQUEST or CANCEL
strMethod = strValue
Case "UID"
' Unique identifier for event
strUid = strValue
Case "DTSTART"
' pull out values into 'mm/dd/yyyy hh:mm:ss' format
strDate = (Mid(strValue, 5, 2) & "/" & Mid(strValue, 7, 2) & _
"/" & Mid(strValue, 1, 4) & " " & Mid(strValue, 10, 2) & ":" & _
Mid(strValue, 12, 2))
dtStart = CDate(strDate)
' put datetime into Outlook format
dtStart = Format(dtStart, "\#m\/d\/yyyy h:mm:ss AM/PM\#")
Case "DTEND"
' pull out values into 'mm/dd/yyyy hh:mm:ss' format
strDate = (Mid(strValue, 5, 2) & "/" & Mid(strValue, 7, 2) & _
"/" & Mid(strValue, 1, 4) & " " & Mid(strValue, 10, 2) & ":" & _
Mid(strValue, 12, 2))
dtEnd = CDate(strDate)
dtEnd = Format(dtEnd, "\#m\/d\/yyyy h:mm:ss AM/PM\#")
Case "SUMMARY"
strSummary = strValue
Case "LOCATION"
strLocation = strValue
Case "ORGANIZER"
' can not set this as of 6-30-2011
strOrganizer = strValue
Case "PRIORITY"
lPriority = Val(strValue)
Case "SEQUENCE"
' if an update must be > 0
lSeq = Val(strValue)
Case "DESCRIPTION"
strDesc = strValue
Case Else
End Select
Next
End If
' check if appointment already exists for given UID
'convert UID to hex. this should match the GlobalAppointmentID if the item was
' imported manually
'Start with the standard preamble (original example had 26 and not 12 here)=======vv
hexUID = "040000008200E00074C5B7101A82E0080000000000000000000000000000000000000000120000007643616C2D55696401000000"
'Now add the provided string
For i = 1 To Len(strUid)
hexUID = hexUID & CStr(Hex(Asc(Mid(strUid, i, 1))))
Next
'Terminate the UID
hexUID = hexUID & "00"
' this filter used if the new field is set to the GlobalAppointmentID
strFilter = "[UID] = '" & hexUID & "'"
Set objAppt = objAppts.Find(strFilter)
If objAppt Is Nothing Then
'New event
Dim myItem As Outlook.AppointmentItem
Set myItem = objOL.CreateItem(olAppointmentItem)
myItem.Start = dtStart
myItem.End = dtEnd
myItem.Subject = strSummary
myItem.Location = strLocation
myItem.Body = strDesc
' this was not working when I did this
' myItem.Organizer = strOrganizer
' add a new property "UID" to the event so it can be updated
myItem.ItemProperties.Add "UID", olText, True
myItem.Save
myItem.ItemProperties.Item("UID").Value = hexUID
myItem.Save
Else
If strMethod = "CANCEL" Then
' remove item from calendar
objAppt.Delete
ElseIf lSeq > 0 Then
' update must have sequence > 0
objAppt.Start = dtStart
objAppt.End = dtEnd
objAppt.Subject = strSummary
objAppt.Location = strLocation
objAppt.Body = strDesc
objAppt.Save
End If
End If
' mark file processed
icsWriteToFile strFile
ExitSub:
Set objAttachments = Nothing
Set objitem = Nothing
Set objSelection = Nothing
Set objOL = Nothing
End Sub
The biggest issue I came across in dealing with Outlook is the ability to update or delete a previously scheduled event. One would think Microsoft could handle the setting of an ID which could then be used to find it consistently. Outlook does assign an ID to events but these get changed if you move them around. The ‘GlobalAppointmentID’ does get set (as a GUID) and remains constant but you have no way of searching for it (sigh). Anyway I get around this by adding a property to any Event created via this process and assign the UID (which is converted into a GUID) to it. This way I can do a simple ‘Find’ of my apppointments and process appropriately. Here are some links related to GUIDs and Outlook
Changing a string into an Outlook Event GUID See answer by banjaxed.
Note this process does not handle recurring appointments
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