How to use UrlFetchApp.fetchAll with Calendar API in google workspace addon - google-apps-script

Question

Our Google Workspace Addon synchronises calendar events from Google Calendar to an external database.
As part of this process we update multiple Calendar Events using the patch command
Calendar.Events.patch({extendedProperties:pp},_e.calendar.calendarId,_e.calendar.id);
The problem we have is that we need to perform this operation multiple times within a limited amount of time (app script will time-out)
We could achieve this with the UrlFetchApp.fetchAll function but unfortunately to call this we would need to call the calendar api directly. Although this is easily done - we do not have the AccessToken as this is not available and is handled by the API.
Does anybody know how to get the accessToken (without pushing the user through a separate OAuth approval process) that is being used by the Calendar API so that we can utilise it to call UrlFetchApp.fetchAll

Answer 1

As long as you have the correct Calendar scope in your add-on, I think you can just pass ScriptApp.getOauthToken() as the token in the UrlFetchApp request:
getOAuthToken()
Gets the OAuth 2.0 access token for the effective user. If the script's OAuth scopes are sufficient to authorize another Google API that normally requires its own OAuth flow (like Google Picker), scripts can bypass the second authorization prompt by passing this token instead. The token expires after a time (a few minutes at minimum); scripts should handle authorization failures and call this method to obtain a fresh token when needed.
The token returned by this method only includes scopes that the script currently needs. Scopes that were previously authorized but are no longer used by the script are not included in the returned token. If additional OAuth scopes are needed beyond what the script itself requires, they can be specified in the script's manifest file.
Return
String — A string representation of the OAuth 2.0 token.
Example Request:
function patchCalendarEvents() {
const calendarId = "calendarId"
const eventIds = [] // your event ID list
const baseUrl = `https://www.googleapis.com/calendar/v3/calendars/${calendarId}/events/{{eventId}}`
const requests = []
eventIds.forEach(function (event) {
requests.push({
"url": baseUrl.replace("{{eventId}}", event),
"method": "PATCH",
"headers": {
"Authorization": "Bearer " + ScriptApp.getOAuthToken()
},
"payload": '{"extendedProperties": {"shared": {"testKey": "Test Value"}}}',
"contentType": "application/json",
})
})
console.log(requests)
const responses = UrlFetchApp.fetchAll(requests)
responses.forEach(function(response) {
console.log(response.getContentText())
})
}