How to store a duration with Doctrine ODM - php

Question

I stored documents which represent events with doctrine. Each $event has an $eventType. Each $eventType has a $duration.
For each $event I will only store the $begin but not the end as it can be calculated with the default $duration of its $eventType.
What would be the most elegant way to store the duration with each eventType?
I would choose a DateInterval annotation if it existed in doctrine. But it does not.
Save the number of seconds of the duration as Integer?
Any other possibility?
The simplified eventType Model looks like this
<?php
/**
* Class EventType
* #ODM\Document(collection="EventType")
*/
class EventType {
/**
* #var $duration int
* #ODM\Int
*/
private $duration;
}

Answer 1

As you mentioned, you can save the duration in seconds.
It's pretty straightforward to have a getEnd method:
/**
* return \DateTime
*/
public function getEnd()
{
$end = clone $this->begin;
return $end->add(new DateInterval('PT' . $this->duration . 'S'));
}
Or you could store the $end date, and not the duration, which you could also calculate:
/**
* return \DateInterval
*/
public function getDuration()
{
return $begin->diff($end);
}
The tricky thing with date differences is the daylight saving time: sometimes you can have
date + 3600seconds == date + 2*3600seconds
So you should think what kind of queries you will make for the end date: will you select events lasting (more or less than) a given amount of time, or will you select events ending (before/after/at) a given date?
Second option is more common, so I would store the end date.