Using PHP to parse a Google Calendar XML - End date is off by a day

Question

I am trying to make a webpage and have the next three events on a Google Calendar show up on the home page. I have been using this PHP (http://james.cridland.net/code/google-calendar.html) to access my XML feed and format it into HTML.

The problem I'm having is that for some reason a new day starts at 11am. For example if my Google Calendar has an event from 10am on the 20th of December that lasts an hour, my PHP output will show an event that starts at 10am on the 20th which ends at 11am on the 21st. Otherwise it is working fine.

I have set my time to local (New Zealand) time on my Google Calendar account, and in PHP using date_default_timezone_set("Pacific/Auckland");

The horrible line that calculates the finish date is

$gCalDateEnd = date($dateformat, strtotime($ns_gd->when->attributes()->endTime)+date("Z",strtotime($ns_gd->when->attributes()->endTime)));

where $dateformat is a string with the date format.

The Google Calendar XML gives a start and finish time of

2011-12-22T10:00:00.000+13:00
2011-12-23T11:00:00.000+13:00

respectively, and the PHP is calculating a timeframe of 10.00am 22 December 2011 to 2.00pm 23 December 2011.

Whats going on?!?!

vstm vstm · Accepted Answer · 2011-12-11T13:10:35

This line is indeed horrible:

$gCalDateEnd = date($dateformat, strtotime($ns_gd->when->attributes()->endTime)+
    date("Z",strtotime($ns_gd->when->attributes()->endTime)));

strtotime can handle this type of ISO 8601 dates just fine. This code-fragment is probably written under the assumption that strtotime dismisses the timezone and returns the datetime in UTC and therefore the timezone "correction" needs to be calculated manually - that's what the +date("Z", ...) stands for (with "Z" the second parameter - the timestamp - is actually ignored).

So in your example 13 hours are added to your dates. And 10:00 + 13:00 = 23:00 (11 pm) which is still on the same day, but 11:00 + 13:00 = 24:00 (12 am) which is actually 00:00 on a new day.

So the correct way to convert the date is:

$gCalDateEnd = date($dateformat, strtotime($ns_gd->when->attributes()->endTime));

Using PHP to parse a Google Calendar XML - End date is off by a day

2 Answers