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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