Create ‘add to calendar’ functionality with ASP

When running events and event registrations on a website, it's very beneficial for users to be able to add the even details to their calendars without having to manually enter them. To do this, you need to generate a .vcs file or output to send to the user. You can either generate this and return it in .vcs encoding, but in this code example I'll show you how to actually create a .vcs file, and store it on the server.

This code assume that you've already got the event details, and loaded them into the descriptive variables in the code below:

sub generateCalendarFile( intEvent )
dim strDtStart, strTmStart, strDtEnd, strTmEnd, strTitle, strDesc, strAddress, strCity
dim strProvince, strRegURL, strCECid, strCal, strLinktoReg

strAddress = strAddress & "=0D=0A" & strCity & ", " & strProvince
strDesc = strDesc & "=0D=0A=0D=0A" & strAddress
strDesc = cleanString( strDesc ) 'function further down

if isEmpty( strRegURL ) or trim( strRegURL ) = "" then
strLinktoReg = "default registration URL"
   else
strLinktoReg = strRegURL
end if
strDesc = strDesc & "=0D=0A=0D=0ADon't forget to register!=0D=0A" & replace( strLinkToReg, "=", "=3D" )

strCal = "BEGIN:VCALENDAR" & vbCrLf & _
   "BEGIN:VEVENT" & vbCrLf & _
   "SUMMARY;CHARSET=ISO-8859-1;ENCODING=quoted-printable:" & strTitle & vbCrLf & _
   "DESCRIPTION;CHARSET=ISO-8859-1;ENCODING=quoted-printable:" & strDesc & vbCrLf & _
   "DTSTART:" & vCalDate( strDtStart, strTmStart ) & vbCrLf & _
   "DTEND:" & vCalDate( strDtEnd, strTmEnd ) & vbCrLf & _
   "END:VEVENT" & vbCrLf & _
   "END:VCALENDAR"

dim vCalPath, vCalFile, strFTPcmd, objFSP, objWrite
vCalPath = Request.ServerVariables("APPL_PHYSICAL_PATH") & "downloadsevents"
set objFSO = Server.CreateObject("Scripting.FileSystemObject")
if Not objFSO.FolderExists( vCalPath ) then call errorMessage( vCalPath & " is an invalid path!" )

vCalFile = intEvent & "_" & intLanguage & ".vcs"

set objWrite = objFSO.OpenTextFile( vCalPath & "" & vCalFile, 2, true )
objWrite.Write(strCal)
objWrite.Close()
set objWrite = nothing
set objFSO = nothing

end sub

For the .vcs file format, the date and time need to be converted to a rather strange format. So here's the function to take the date and time, convert them to and return them in .vcs format:

function vCalDate( strDate, strTime )
dim arDate
arDate = split( strDate, "-" )
strDate = ""
for j = 0 to 2
if len( arDate( j ) ) = 1 then arDate( j ) = "0" & arDate( j )
strDate = strDate & arDate( j )
next

strTime = replace( strTime, ":", "" )
strTime = cLng( strTime ) + 40000
if strTime > 240000 then
strDate = cStr( cLng( strDate ) + 1 )
strTime = strTime – 240000
end if
strTime = cStr( strTime )
if len( strTime ) < 6 then
do until len( strTime ) = 6
strTime = "0" & strTime
loop
end if
vCalDate = strDate & "T" & strTime & "Z"
end function

One other thing: if you have any URLs or HTML enchoded characters (like ®, etc), they don't play well in the .vcs files. So you need to remove the URLs, and re-encode the symbols in UNICDE format. Here's the function to do that

function cleanString( strToConvert )
'=== remove URLS
'=== takes out HTML friendly chars, and converts to UNICODE equivalent
dim objRegExp, matches, strChar
set objRegExp    = New RegExp
objRegExp.Pattern    = "<a.*?</a>"
objRegExp.Global = true
strToConvert    = objRegExp.Replace( strToConvert, "" )
set objRegExp    = nothing

set objRegExp    = New RegExp
objRegExp.Pattern    = "&#.*?;"
objRegExp.Global = true
set matches    = objRegExp.Execute( strToConvert )

for each j in matches
strChar = j.value
strChar = cInt( replace( replace( strChar, "&#", "" ), ";", "" ) )
strChar = chr( strChar )
strToConvert = replace( strToConvert, j.value, strChar )
next

set objRegExp    = nothing
set matches    = nothing
cleanString    = strToConvert

end function

Tagged as: add, ASP, calendar', Create, functionality, to, with

Create ‘add to calendar’ functionality with ASP

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