DateTime with Timezone in php and Microsoft Graph API - php

Question

I'm trying to read the calendar entries of rooms and output the next three events on their calendar. However I am testing first to see if I can get just the first 3 events of the day, but it seems the timezone or something else is causing it to not show events correctly.
This is a function I wrote:
function mb_get_meetings($mb_email = null, $mb_proxy = false, $mb_datetime_start = null, $mb_datetime_finish = null)
{
date_default_timezone_set('Australia/Melbourne');
// get the Microsoft Open Graph API
$mb_msgraph = json_decode(mb_microsoft_opengraph($mb_proxy), true); // custom function to get Beaker Token + $mb_proxy for internal proxy on or off for dev testing
$mb_msgraph_token = $mb_msgraph['access_token'];
$mb_datetimenow = new DateTime();
$mb_datetimezone = new DateTimeZone('Australia/Melbourne');
$mb_datetimenow->setTimezone($mb_datetimezone);
$mb_datetime_start = new DateTime($mb_datetime_start, $mb_datetimezone);
$mb_datetime_finish = new DateTime($mb_datetime_finish, $mb_datetimezone);
$mb_datetime_start = $mb_datetime_start->format('Y-m-d\TH:i:s.u');
$mb_datetime_finish = $mb_datetime_finish->format('Y-m-d\TH:i:s.u');
$mb_url_string = 'https://graph.microsoft.com/v1.0/users/' . $mb_email . '/calendar/calendarView?startDateTime=' . $mb_datetime_start . '&endDateTime=' . $mb_datetime_finish;
$mb_args = array(
'headers' => array(
'Authorization' => 'Bearer ' . $mb_msgraph_token,
'Content-Type' => 'application/x-www-form-urlencoded;charset=UTF-8',
'Prefer' => 'outlook.timezone="Australia/Melbourne"'
),
'httpversion' => '1.1'
);
$mb_output = wp_remote_get($mb_url_string, $mb_args);
$mb_output = wp_remote_retrieve_body($mb_output);
return $mb_output;
}
I am using Wordpress as the backend and it does retrieve the body.
In my frontend page I call:
$mbroom = (mb_get_meetings('email#domain.tld', true, 'today 7am', 'today 7pm'));
$mbroom = json_decode($mbroom, true);
$mbroom = $mbroom['value'];
foreach ($mbroom as $k => $v) {
// get the first 3 entries
if ($k < 3) {
print_r($k);
print_r($v['subject']);
print_r(date('g:i', strtotime($v['start']['dateTime']));
print_r(date('g:i', strtotime($v['end']['dateTime']));
print_r($v['organizer']['emailAddress']['name']);
echo '<hr>';
}
}
In the results, I will get sometimes no calendar entries while other times I might get entries for 2pm but not anything from 8am. I have tried changing it to hardcoded YYYY-MM-DDD 08:00 and YYYY-MM-DD 20:00 but to no avail. I have also tried yesterday and tomorrow but none/incorrect results.
I also tried booking an entire day with 30-minute meetings and that too wasn't working.
Am I doing something wrong?

Answer 1

I suggest sending the startDateTime and endDateTime parameters in UTC, formatted as ISO 8601 as described in the docs (https://learn.microsoft.com/en-us/graph/api/user-list-calendarview?view=graph-rest-1.0&tabs=http), which you have done. However, I'd suggest using a PHP constant, since it's less error-prone (https://www.php.net/manual/en/class.datetimeinterface.php#datetime.constants.iso8601). Doing something like the following for those parameters:
$startDateTime = new DateTime(date("Y-m-d H:i:s"));
$startDateTime = $startDateTime->format(DATE_ISO8601);
$startDateTime = substr($startDateTime, 0, strpos($startDateTime, '+'));
Edit:
Using substring to remove the locale part of the DateTime string was probably a naïve thing to do, but it does serve the purpose.