Description
Think of the following two documents:
<?php
/** @Document() */
class Survey {
/** @Id() */
public $id;
/** @ReferenceMany(targetDocument="Question", embedFields={"question"}) */
public $questions;
}
/** @Document() */
class Question {
/** @Id() */
public $id;
/** @String() */
public $question;
}The mongo stored documents for surveys would look like:
{
"_id": "...",
"questions": [
{ "$ref": "...", "$id": "...", "$db": "...", "question": "Is ODM awesome?" },
{ "$ref": "...", "$id": "...", "$db": "...", "question": "Isn't this such a great feature?!" },
]
}So that if you do the following, no extra finds will be triggered unless the field wasn't embedded in the referenced document data:
<?php
$questions = [];
foreach ($surveyRepository->find("...")->getQuestions() as $question) {
$questions[$question->getId()] = $question->getQuestion();
}Updates to the question may cascade unless configured to not do so, or the other way around. In most of my cases, a cascade can occur.. but if someone happens to use this feature on an active database with many records, then shit can hit the fan!
It'd be easy to create a document and manage it as if it were it's own document and just associate that to one thing and be embedded. I tend to use it this way in many cases... thus would limit many finds.
Another thing that can also solve this problem is to introduce caching, but that's another topic.