Google Apps Calendar free/busy query POST with curl - php

Question

I am trying to do a free/busy query on a Google Resource Calendar (Google Apps). The API documentation for Freebusy query gives these directions about the request:
HTTP Request:
POST https://www.googleapis.com/calendar/v3/freeBusy
Request Body Structure:
{ "timeMin": {datetime},
"timeMax": {datetime},
"items": [
{"id": {string}
}
]
}
Here's my attempt, using curl:
$url = "https://www.googleapis.com/calendar/v3/freeBusy";
global $headers; // holds ClientLogin authentification
$freebusy_post = array(
"timeMin" => '2012-12-31T00:00:00',
"timeMax" => '2013-01-08T23:00:00',
"timeZone" => 'America/New York',
/*** "items" below commented out because posting a multidimensional array returns an
"Array to string conversion" error. However, I think the API requires
"items" to be an array. ***/
//"items" => array(
// "id" => "https://www.googleapis.com/calendar/v3/calendars/gdev.wellesley.edu_313736333535343332#resource.calendar.google.com"
// )
/*** My attempt at using a plain string instead of an array ***/
"items" => "gdev.wellesley.edu_313736333535343332#resource.calendar.google.com",
);
$ch = curl_init();
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $freebusy_post);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_TIMEOUT, 60);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_URL, $url);
$data = curl_exec($ch);
print_r($data);
My problem: $data doesn't print anything.
I'm brand new to PHP, curl, and the Google Apps Calendar API. I'd love any help/ lessons/ advice you can offer!

Answer 1

Not sure, but you have probably to convert the php array to a json first.
$freebusyjson = json_encode($freebusy_post);

Answer 2

i started with your code and modified it and the following worked for me...
Note how i formatted the calendar ID in the item variable. I also only needed to attach an API key to the URL as it is a public calendar. I don't think I needed it initially, but then I reached the number of requests that could be made without using an API key.
Finally, note the format of the Time/Date. I'm saying this is the only way to do it, but it worked for me.
$url = "https://www.googleapis.com/calendar/v3/freeBusy/?key=MY_API_KEY";
$freebusy_post = array(
"timeMin" => '2016-11-01T00:00:00.000Z',
"timeMax" => '2016-12-21T00:00:00.000Z',
"timeZone" => ' America/New York',
"items" => array(array('id'=>"mywebsite.com_randomlettershere#group.calendar.google.com")),
);
$freebusy_post = json_encode($freebusy_post);
$ch = curl_init();curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $freebusy_post);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_TIMEOUT, 60);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json'));
curl_setopt($ch, CURLOPT_URL, $url);
$data = curl_exec($ch);
print_r($data);