Fill a partial collection with all related entities in Doctrine 2 - php

Question

Say I had the following query that returns a User entity with the associated Post entities that have been flagged (this is just for demonstration):
SELECT u, p
FROM User u
LEFT JOIN u.posts p
WHERE p.isFlagged = true
Once I've used this, I then want to access all the posts for that user, regardless of isFlagged. Is there a simple way to refresh the $user->posts collection so that it is then a complete collection of all the users posts?
I don't want to just pull out all of the posts in the query (as they may not be needed), and the code that needs the complete collection isn't going to be aware of the query this entity came from.

Answer 1

What you are doing here is broken:
SELECT
u, p
FROM
User u
JOIN
u.posts p
WITH
p.isFlagged = true
This will hydrate `User#posts" collection with wrong values, which results in broken logic, broken object graph, broken everything.
You should solve this at DQL level with something like following:
SELECT
u, p
FROM
User u
JOIN
u.posts p
JOIN
u.posts j
WITH
j.isFlagged = true
This will basically hydrate the correct posts collection in the user object, without any intermediate (broken) state.
EDIT: I misunderstood the question because I've based my thoughts on #Athlan's answer, which is fundamentally wrong (flushing a broken collection is really wrong). This is my previous answer, which I still believe is interesting because it solves the problem, but not in a really correct way.
This question actually made me curious to see if the ORM refreshed collections as I expected it to do.
I wrote the test in this branch.
Basically, what you need to do is simply:
$entityManager->refresh($entity);
Here's the relevant part of the test:
$foo = new DDC2666Foo();
$this->_em->persist($foo);
$this->_em->flush();
$this->_em->clear();
$fetchedFoo = $this->_em->find(__NAMESPACE__ . '\DDC2666Foo', $foo->id);
$fetchedFoo->bars->add(new DDC2666Bar());
$this->assertCount(1, $fetchedFoo->bars);
$this->_em->refresh($fetchedFoo);
$this->assertCount(0, $fetchedFoo->bars, 'The collection was reset');
There's just the disadvantage that this will also re-fetch your entity, but the ORM itself does not provide a facade to refresh single collections.
That is also a good thing anyway, since this way, you won't break encapsulation, which may lead to unexpected (and hard to debug) behaviour in your code.

Answer 2

I had this same issue and ended up here. Refreshing isn't an option for me because I have a list and I don't want to make those extra queries.
What you really need here is to add a "fake" join to do the filtering, and leave the original one without a condition... to make this clear:
SELECT u, p
FROM User u
LEFT JOIN u.posts p
LEFT JOIN u.posts p2
WHERE p2.isFlagged = true
Note that I'm leaving p2 out from the select clause, it's just for filtering purposes.

Answer 3

I find the other solutions very non-satisfying because many entities will get hydrated that I'm not at all interested in. If the vast majority of the posts have isFlagged = 0 then the performance impact is huge.
Here's an alternate solution which involves swapping around the relationship between the entities. However it is not entirely equivalent to what the original question asked for. Yet it might be useful to others having this issue:
SELECT p, u
FROM Post p
JOIN p.user u
WHERE p.isFlagged = true
The differences between this and the other solutions is that it will no longer return users that do not have any posts or any flagged posts. This may or may not be what you want.