Fullcalendar and timezones. Help, I'm doing it wrong

Question

I'm doing it wrong somehow. I'm getting tripped up on timezones with Fullcalendar . I've tried setting ignoreTimezone to true and false, but it doesn't seem to matter. It's in the code below in two places because I wasn't sure from the doc where it goes.

My data source is a hidden form field. Data that goes out of FullCalendar is adjusted by adding 5 hours (CDT). Data that goes in to FullCalendar isn't adjusted by removing 5 hours.

On the back-end, I'm just saving and returning the JSON string without processing it (or even decoding it)

Page Load:
  Data In: Empty, no data
  Data Edit: drag from noon to 2pm (CDT), then submit form
  Data Out: Use clientEvent to get data, and JSON.stringify to put into form field.
    [{"id":6844,"title":"Open","start":"2011-04-19T17:00:00.000Z","end":"2011-04-19T19:00:00.000Z","allDay":false}]

Page Load (after submitting form):
  Data In: Use JSON.parse to load data from hidden form field.  This is the incoming data, but the event is shifted to 5pm (CDT) in the control.  
    [{"id":6844,"title":"Open","start":"2011-04-19T17:00:00.000Z","end":"2011-04-19T19:00:00.000Z","allDay":false}]
  Data Out:  Without changing the control, it's now:
    [{"id":6844,"title":"Open","start":"2011-04-19T22:00:00.000Z","end":"2011-04-20T00:00:00.000Z","allDay":false}]

I setup the Fullcalendar like this:

// Fullcalendar for business hours page

jQuery(document).ready(function() {

  jQuery('#edit-submit').bind("click", business_hours_set);
  jQuery('#edit-preview').bind("click", business_hours_set);

  jQuery('#calendar').fullCalendar({

    // configure display
    header: {
      left: '',
      center: '',
      right: ''
    },
    ignoreTimezone: false,
    defaultView: 'agendaWeek',
    allDaySlot: false,
    firstHour: 8,

    // configure selection for event creation
    selectable: true,
    selectHelper: true,
    select: business_hours_add,

    // configure data source
    editable: true,
    eventSources: [
    {
      events: jQuery.parseJSON(jQuery('#fullcalendar_data').val()),
      color: '#992B0A',
      textColor: 'white',
      ignoreTimezone: false
    }
    ],

    // configure editing
    eventClick: function(calEvent) {
      business_hours_delete(calEvent.id);
    }
  });
  alert(jQuery('#fullcalendar_data').val());
});

function business_hours_add(startDate, endDate) {
  var calendar = jQuery('#calendar');
  var newid = Math.ceil(Math.random()*64000);
  calendar.fullCalendar('renderEvent',
  {
    id: newid,
    title: "Open",
    start: startDate,
    end: endDate,
    allDay: false
  },
  true // make the event "stick"
  );
  calendar.fullCalendar('unselect');
}

var business_hours_selectedId = -1;
function business_hours_delete(id) {

  business_hours_selectedId = id;

  jQuery( "#dialog-confirm" ).dialog({
    resizable: false,
    height:160,
    modal: true,
    buttons: {
      "Yes, delete!": function() {
        calendar = jQuery('#calendar');
        calendar.fullCalendar( 'removeEvents', business_hours_selectedId);
        jQuery( this ).dialog( "close" );
      },
      Cancel: function() {
        jQuery( this ).dialog( "close" );
      }
    }
  }, id);
}

function business_hours_set() {
  var data = jQuery('#calendar').fullCalendar( 'clientEvents' );

  // data is cyclical.  Create a new data structure to stringify.
  var ret = [];
  for(var i=0; i<data.length; i++) {
    var datum = {
      id: data[i].id,
      title: data[i].title,
      start: data[i].start,
      end: data[i].end,
      allDay: data[i].allDay
    }
    ret[i] = datum;
  }
  // stringify and return
  jQuery('#fullcalendar_data').val(JSON.stringify(ret));
  alert(JSON.stringify(ret));
}

What am I doing wrong?

Thanks in advance, Mike

Answer 1

I had the same timeshift in FullCalendar. Check out your timezone on server, when I changed it to my own it help me. You may try to do it in few ways:

On serer:

[root@mx ~]# mv /etc/localtime /etc/localtime.old

[root@mx ~]# ln -s /usr/share/zoneinfo/Europe/Moscow /etc/localtime

Or in PHP script (which returns JSON string):

date_default_timezone_set('Europe/Moscow');

PS Don't forget to change "Europe/Moscow" to your values :-)

Then you have to set your valid time in new time zone ("date" command);

Answer 2

You are serializing CDT-adjusted dates as UTC dates (thus getting a 5 hour shift) so when they are read back in they get re-adjusted to CDT, and so on..

Because there isn't a way to set a timezone on JS date objects, Fullcalendar represents them internally as UTC dates, but adjusts for timezone offset on input time.

$.fullCalendar.parseISO8601('2011-04-19T17:00:00.000-05:00');
// Tue Apr 19 2011 22:00:00 GMT+0000 (GMT)  <-- note time shift

This is why, when you serialize to JSON, you get a string with the "Zulu" (UTC) timezone:

var dt = $.fullCalendar.parseISO8601('2011-04-19T17:00:00.000-05:00');
JSON.stringify( dt ); // "2011-04-19T22:00:00.000Z"

You need the date back to your timezone. It doesn't look like Fullcalendar has this so you'll need to to the work:

// detect local timezone offset
var localoffset = (new Date()).getTimezoneOffset();
// "unadjust" date
ret = new Date( ret.valueOf() + (localoffset * 60 * 1000) );

// serialize
function pad (n) { return String(n).replace(/^(-?)(\d)$/,'$10$2'); }
JSON.stringify( ret )
     // replace Z timezone with current
     .replace('Z', pad(Math.floor(localoffset / 60))+':'+ pad(localoffset % 60));

// should result in something like: "2011-04-21T19:00:00.000-05:00"

There may be a better way of solving this using Fullcalendar but I am not familiar with it.

Code is untested: I live in GMT with no-DST and don't really want to mess with my system just to see it work (YMMW). :-)