Doctrine 2 OneToMany Association - Cascade Persist From Both Sides - php

Question

Disclaimer: n00b to Doctrine, not ORMs in general, or the data mapper pattern, just Doctrine. Not sure if I'm missing something (references to the documentation are welcome if they're specific! I've read thoroughly though) or there is another preferred approach. A big part of this question is how to do it the right way, not necessarily how to do it in general.
The deets: I've got a one to many association between two entities: Calendar and Event. One calendar can have many events. Relevant code:
Calendar Entity
<?php namespace MyPackage\Src {
use \Doctrine\Common\Collections\ArrayColleciton;
class Calendar {
/**
* #OneToMany(targetEntity="MyPackage\Src\Event", mappedBy="calendarInstance", cascade={"all"})
*/
protected $associatedEvents;
public function __construct(){
$this->associatedEvents = new ArrayCollection();
}
public function addEvent( Event $eventObj ){
$eventObj->setCalendarInstance($this);
$this->associatedEvents->add($eventObj);
}
public function getEvents(){
return $this->associatedEvents;
}
// Assume entityManager() returns... an entity manager instance
public function save(){
$this->entityManager()->persist($this);
$this->entityManager()->flush();
return $this;
}
}
}
Event Entity
<?php namespace MyPackage\Src {
class Event {
/**
* #ManyToOne(targetEntity="MyPackage\Src\Calendar", inversedBy="associatedEvents")
* #JoinColumn(name="calendarID", referencedColumnName="id", nullable=false)
*/
protected $calendarInstance;
public function setCalendarInstance( Calendar $calObj ){
$this->calendarInstance = $calObj;
}
// Assume entityManager() returns... an entity manager instance
public function save(){
$this->entityManager()->persist($this);
$this->entityManager()->flush();
return $this;
}
}
}
Semantics of the ORM state that "Doctrine will only check the owning side of an association for changes" (<- proof of reading docs). So doing the following works fine when creating a new event (assuming cascade persist is enforced by the Calendar, which I have set with "all"), and then gett'ing the ArrayCollection from the calendar instance.
<?php
// Assume this returns a successfully persisted entity...
$cal = Calendar::getByID(1);
// Create a new event
$event = new Event();
$event->setTitle('Wowza');
// Associate the event to the calendar
$cal->addEvent($event);
$cal->save();
// Yields expected results (ie. ArrayCollection is kept in-sync)
echo count($cal->getEvents()); // "1"
Meow then... Lets say for some funny reason I want to create an association from the event side, like so:
<?php
// Assume this returns a successfully persisted entity...
$cal = Calendar::getByID(1);
// Create a new event
$event = new Event();
$event->setTitle('Dewalt Power Tools');
// Associate VIA EVENT
$event->setCalendarInstance($cal);
$event->save();
// ArrayCollection in the Calendar instance is out of sync
echo count($cal->getEvents()); // "0"
Persisting the event in this manner does work (it gets saved to the DB) - but now the entity manager is out of sync when trying to access associated events from the Calendar. Further, its understandable why: in the setCalendarInstance() method of the Event class, all thats happening is
$this->calendarInstance = $calendar;
I've tried the following (which actually works, it just feels really naughty)
$this->calendarInstance = $calendar;
if( ! $this->calendarInstance->getEvents()->contains($this) ){
$this->calendarInstance->getEvents()->add($this);
}
BUT, this feels very strongly like I'm breaking proper encapsulation, which is important to me. Am I being silly, and its OK to ->add() to the returned ArrayCollection of the Calendar instance, outside of the Calendar class? (Thats what I mean this feels wrong; the ArrayCollection is a protected property of Calendar and I feel like it shouldn't be modified externally).
---- OR ----
Should I enforce creating the association only from the owning side (the Calendar), and not allow doing $event->setCalendarInstance() and then saving the event. Which again brings up another point on encapsulation, that setCalendarInstance must be a public method in order for the Calendar's addEvents() method to work (so how would I prevent some poor soul inheriting my codebase from doing it improperly)?
Thanks, interested to hear approaches to this.
** Edit **
Further funny business: Going the route of creating a new event, passing the calendar instance, and then persisting the new event - here is where discrepancies seem to exist:
// Get an existing Calendar that has one Event
$calObj = Calendar::getByID(1);
echo count($calObj->getEvents()); // "1"
// Add from event side
$event = new Event();
$event->setTitle('Pinkys Brain');
$event->setCalendarInstance($calObj);
$event->save();
// I would think this would be "2" now...
echo count($calObj->getEvents()); // Still "1"
BUT... this works, and feels shloppy.
// Get an existing Calendar that has one Event
$calObj = Calendar::getByID(1);
echo count($calObj->getEvents()); // "1"
// Add from event side
$event = new Event();
$event->setTitle('Pinkys Brain');
$event->setCalendarInstance($calObj);
$event->save();
// Clear the entity manager on the existing $calObj
$calObj->entityManager()->clear();
// Now get a NEW instance of the same calendar
$calObjAgain = Calendar::getByID(1);
echo count($calObjAgain->getEvents()); // "2"