Google Apps Script to automatically create, edit and delete events on work calendar for personal calendar events. Instructions on how to set up can be found at https://medium.com/@willroman/auto-block-time-on-your-work-google-calendar-for-your-personal-events-2a752ae91dab

block_personal_appts

function sync() {

  var id="XXXXXXXXXX"; // CHANGE - id of the secondary calendar to pull events from

  var today=new Date();
  var enddate=new Date();
  enddate.setDate(today.getDate()+7); // how many days in advance to monitor and block off time
  
  var secondaryCal=CalendarApp.getCalendarById(id);
  var secondaryEvents=secondaryCal.getEvents(today,enddate);
  
  var primaryCal=CalendarApp.getDefaultCalendar();
  var primaryEvents=primaryCal.getEvents(today,enddate); // all primary calendar events
  
  var primaryEventTitle="Personal appt"; // update this to the text you'd like to appear in the new events created in primary calendar
  
  var stat=1;
  var evi, existingEvent; 
  var primaryEventsFiltered = []; // to contain primary calendar events that were previously created from secondary calendar
  var primaryEventsUpdated = []; // to contain primary calendar events that were updated from secondary calendar
  var primaryEventsCreated = []; // to contain primary calendar events that were created from secondary calendar
  var primaryEventsDeleted = []; // to contain primary calendar events previously created that have been deleted from secondary calendar

  Logger.log('Number of primaryEvents: ' + primaryEvents.length);  
  Logger.log('Number of secondaryEvents: ' + secondaryEvents.length);
  
  // create filtered list of existing primary calendar events that were previously created from the secondary calendar
  for (pev in primaryEvents)
  {
    var pEvent = primaryEvents[pev];
    if (pEvent.getTitle() == primaryEventTitle)
    { primaryEventsFiltered.push(pEvent); }
  }
  
  // process all events in secondary calendar
  for (sev in secondaryEvents)
  {
    stat=1;
    evi=secondaryEvents[sev];
    
    // if the secondary event has already been blocked in the primary calendar, update it
    for (existingEvent in primaryEventsFiltered)
      {
        var pEvent = primaryEventsFiltered[existingEvent];
        var secondaryTitle = evi.getTitle();
        var secondaryDesc = evi.getDescription();
        if ((pEvent.getStartTime().getTime()==evi.getStartTime().getTime()) && (pEvent.getEndTime().getTime()==evi.getEndTime().getTime()))
        {
          stat=0;
          pEvent.setTitle(primaryEventTitle);
          pEvent.setDescription(secondaryTitle + '\n\n' + secondaryDesc);
          // event.setDescription(evi.getTitle() + '\n\n' + evi.getDescription());
          pEvent.setVisibility(CalendarApp.Visibility.PRIVATE); // set blocked time as private appointments in work calendar
          primaryEventsUpdated.push(pEvent.getId());
          Logger.log('PRIMARY EVENT UPDATED'
                     + '\nprimaryId: ' + pEvent.getId() + ' \nprimaryTitle: ' + pEvent.getTitle() + ' \nprimaryDesc: ' + pEvent.getDescription());
        } 
      }

    if (stat==0) continue;    
    
    var d = evi.getStartTime();
    var n = d.getDay();

    if (evi.isAllDayEvent())
    {
      continue; // Do nothing if the event is an all-day or multi-day event. This script only syncs hour-based events
    }
    else if (n==1 || n==2 || n==3 || n==4 || n==5) // skip weekends. Delete this if you want to include weekends
    // if the secondary event does not exist in the primary calendar, create it
    {
      var newEvent = primaryCal.createEvent(primaryEventTitle,evi.getStartTime(),evi.getEndTime()); // change the Booked text to whatever you would like your merged event titles to be
      // alternative version below that copies the exact secondary event information into the primary calendar event
      // var newEvent = primaryCal.createEvent(evi.getTitle(),evi.getStartTime(),evi.getEndTime(), {location: evi.getLocation(), description: evi.getDescription()});  
      newEvent.setDescription(evi.getTitle() + '\n\n' + evi.getDescription());
      newEvent.setVisibility(CalendarApp.Visibility.PRIVATE); // set blocked time as private appointments in work calendar
      newEvent.removeAllReminders(); // so you don't get double notifications. Delete this if you want to keep the default reminders for your newly created primary calendar events
      primaryEventsCreated.push(newEvent.getId());
      Logger.log('PRIMARY EVENT CREATED'
                 + '\nprimaryId: ' + newEvent.getId() + '\nprimaryTitle: ' + newEvent.getTitle() + '\nprimaryDesc ' + newEvent.getDescription() + '\n');
    }
  }

  // if a primary event previously created no longer exists in the secondary calendar, delete it
  for (pev in primaryEventsFiltered)
  {
    var pevIsUpdatedIndex = primaryEventsUpdated.indexOf(primaryEventsFiltered[pev].getId());
    if (pevIsUpdatedIndex == -1)
    { 
      var pevIdToDelete = primaryEventsFiltered[pev].getId();
      Logger.log(pevIdToDelete + ' deleted');
      primaryEventsDeleted.push(pevIdToDelete);
      primaryEventsFiltered[pev].deleteEvent();
    }
  }  

  Logger.log('Primary events previously created: ' + primaryEventsFiltered.length);
  Logger.log('Primary events updated: ' + primaryEventsUpdated.length);
  Logger.log('Primary events deleted: ' + primaryEventsDeleted.length);
  Logger.log('Primary events created: ' + primaryEventsCreated.length);

}  

Utilities.sleep(sec1000); // added to line 39 to prevent "too many updates" error on a busy calendar. I'm no coder, probably a better method.

How can I sync all-day or multi-day events?

Utilities.sleep(sec1000); // added to line 39 to prevent "too many updates" error on a busy calendar. I'm no coder, probably a better method.

@elabrant
Close. It should be this which worked great for me when inserted to line 40:
Utilities.sleep(1000); // added to prevent "too many updates" error on a busy calendar

@jboudreau77 I figured out why this is happening. On line 28 when the primaryEvents array is being built, it's looking for events with the primaryEventTitle. If you're like me, and changed the code on lines 72 and 74, then there will be nothing in the primaryEvents array, because each event has a different name.

@ttrahan got a quick fix? I'm not the best coder, but I can give it a shot.

@jboudreau77 I think I got a fix working here: https://github.com/ReaganHelms/calendar-sync/tree/main

Hello! I did a tiny patch to add support for multiple secondary calendars. Feel free to ignore it. https://gist.github.com/vaurora/a6deb299574b3c23652d776915025b9e

I have updated this script to also make it much more efficient (helping the planet just a little), and configurable.

Is there a way to alter this to include multi-day events? (for example, personal holidays)

Additionally is there a way to omit the personal events title and notes from being synced to the "busy" event?

Hi there. Thanks for this. a few questions:
1 - when i set the trigger to "sync", it creates double events. when i set it to hourly update it does not. is there any way to get it working wtih sync trigger without the double events?
2 - i'd like it to only create primary calendar events that occur after 9am on weekdays. is there any way to adjust it for this?
3 - I'd like it to be able to create primary calendar events of all day events. is there a way to enable all day events? thanks so much!