iCalendar / ICS Module

An easy way to generate appointment (.ics) files to attach to an email.

• Generate create, update, and cancel .ics appointment files
• Add extra details to the appointment such as location, description, organizer, and attendees
• Choose how times are interpreted: as fixed moments (UTC) or as wall-clock times in a specific time zone
• Optionally set a time zone

• None

The Email Connector module is mentioned in the Email headers section as a convenient way to attach the file, but it is not required.

Add the SUB_IcalMessage_CreateFile microflow wherever you want to generate an .ics file. It needs an IcalMessage object as input.

Mandatory fields are the start time, end time, subject, and status (the status maps to the iCal METHOD — see Email headers). The remaining fields are optional, but it's recommended to populate as many as you can for a complete invite.

The AttendeeList parameter requires a list of Attendee objects. Do not rename the Attendee entity or its attributes — the action looks them up by name.

To test the generated files, add the SNIP_ICalendar snippet to a page.

The Localized boolean controls how the start and end values are interpreted:

• true — the dates are treated as real moments in time (a localized Mendix DateTime attribute, or a date you built to represent an actual instant). They are written in UTC, and every calendar client converts them to the recipient's own time zone. The TimeZone parameter is ignored in this mode.
• false or empty — the dates are treated as wall-clock labels (a non-localized attribute). The exact time you set is written as-is under the chosen TimeZone, so 14:00 stays 14:00 in that zone regardless of where the recipient is.

Rule of thumb: use true for "the meeting is at this precise instant," and false for "the meeting is at 14:00 local time, whatever the recipient's zone."

The TimeZone parameter only applies when Localized is false or empty. In localized mode the times are always written in UTC, so this field is ignored.

Leave it empty to fall back to the server's time zone. To set one explicitly, the easiest option is the TimeZone entity that already exists in the System module of Studio Pro — put its Code attribute into the TimeZone field. You can also set it manually if you only ever use one zone, for example Europe/London.

To send an .ics file correctly via email, you need to set the right attachment content type. If you use the Email Connector module, attach the file with its Attachment mechanism and set the attachmentContentType attribute on the Attachment entity. The value should look like this:

text/calendar; charset=utf-8; method=REQUEST; name=event.ics

Make sure the method matches the iCal status you used (REQUEST for a create or update, CANCEL for a cancellation, and so on) — it must be the same value as the METHOD written into the file.

Updates to an existing appointment must use the same UID so that calendar clients recognise it as the same event. You should also increase the sequence number on each update: the first mail carries an .ics with sequence 0, the next one 1, and so on (for example, when you later cancel an appointment you already sent).

Because of this, it's wise to commit the IcalMessage object after sending it the first time, then retrieve that same object when sending an update. SUB_IcalMessage_CreateFile increments the sequence number for you.

Please feel free to raise issues, share suggestions, or request new features on the GitHub repository: iCalendar GitHub Issues