Within Google Apps Script you have two ways to interact with Google Calendar; the Calendar Service and the Advanced Calendar Service (aka Calendar API) which must be enabled via Advanced Google Services.
The ACS uses the resource representations from the Google Calendar API, so the extendedProperties
are available as a part of the event objects you can obtain through the API.
Here's a simple modification of the example from the ACS docs that will log the "talk-number" for every event that has one.
function listNext10Events() {
var calendarId = 'primary';
var now = new Date();
var events = Calendar.Events.list(calendarId, {
timeMin: now.toISOString(),
singleEvents: true,
orderBy: 'startTime',
maxResults: 10
});
if (events.items && events.items.length > 0) {
for (var i = 0; i < events.items.length; i++) {
var event = events.items[i];
if (event.start.date) {
// All-day event.
var start = parseDate(event.start.date);
Logger.log('%s (%s)', event.summary, start.toLocaleDateString());
} else {
var start = parseDate(event.start.dateTime);
Logger.log('%s (%s)', event.summary, start.toLocaleString());
}
/********************************************************************/
if (event.hasOwnProperty("talk-number"))
Logger.log(event.extendedProperties.private["talk-number"]);
/********************************************************************/
}
} else {
Logger.log('No events found.');
}
}
You can update your function with this:
var eventId = events[i].getId().replace(/@.*/,''); // Remove @google.com from eventId
var event = Calendar.Events.get(calendarId, eventId)
myTalkNo = event.extendedProperties.private["talk-number"];