Doctrine ODM: Cannot prime->(true) getSingleResult(); throws cursor error - mongodb-php

Question

I have a document that has a ReferenceMany attribute to another document. The reference is setup fine, and the data is returned from the query fine, but each document in the arraycollection is returned as a proxy. On this site, I saw it was mentioned I should add ->prime(true) in order to return the actual referenced documents.
When that ArrayCollection of documents is returned, I am running a loop of ids I have submitted to the server to remove them from the referenced collection. The removeElement method is not working b/c the returned documents are proxies, and I am comparing an actual document vs. those proxies. So basically I am trying to:
Look up a single document
Force all documents in the ReferenceMany attribute to be actual documents and not Proxy documents
Loop through my array of id's and load each document
Send the document to the removeElement method
On the first getSingleResult query method below, I am getting an error cannot modify cursor after beginning iteration. I saw a thread on this site mention you should prime the results in order to get actual documents back instead of proxies, and in his example, he used getSingleResult.
$q = $this->dm->createQueryBuilder('\FH\Document\Person')->field('target')->prime(true)->field('id')->equals($data->p_id);
$person = $q->getQuery()->getSingleResult();
foreach($data->loc_id as $loc) {
$location = $this->dm->createQueryBuilder('\FH\Document\Location')->field('id')->equals(new \MongoId($loc))->getQuery()->getSingleResult();
$person->removeTarget($location);
}
....
....
....
public function removeTarget($document)
{
$this->target->removeElement($document);
return $this;
}
If I remove ->prime(true) from the first query, it doesn't throw an error, yet it doesn't actually remove any elements even though I breakpoint on the method, compare the two documents, and the data is exactly the same, except in $this->target they are Location Proxy documents, and the loaded one is an actual Location Document.
Can I prime the single result somehow so I can use the ArrayCollection methods properly, or do I need to just do some for loop and compare ids?
UPDATE
So here is an update showing the problem I am having. While the solution below would work just using the MongoId(s), when I submit an actual Document class, it never actually removes the document. The ArrayCollection comes back from Doctrine as a PersistentCollection. Each element in $this->coll is of this Document type:
DocumentProxy\__CG__\FH\Document\Location
And the actual Document is this:
FH\Document\Location
The removeElement method does an array_search like this:
public function removeElement($element)
{
$key = array_search($element, $this->_elements, true);
if ($key !== false) {
unset($this->_elements[$key]);
return true;
}
return false;
}
So because the object types are not exactly the same, even though the proxy object should be inheriting from the actual Document I created, $key always returns 0 (false), so the element is not removed. Everything between the two documents are exactly the same, except the object type.
Like I said, I guess I can do it by MongoId, but why isn't it working by submitting the entire object?

Answer 1

Don't worry about the prime(true) stuff for just now. All that does is tell doctrine to pull the referenced data now, so it doesn't have to make multiple calls to the database when you iterate over the cursor.
What I would do is change your removeTarget method to do the following.
$this->dm->createQueryBuilder('\FH\Document\Person')->field('id')->equals($data->p_id);
$person = $q->getQuery()->getSingleResult();
$person->removeTargets($data->loc_id);
Person.php
public function removeTargets($targets)
{
foreach ($targets as $target) {
$this->removeTarget($target);
}
}
public function removeTarget($target)
{
if ($target instanceof \FH\Document\Location) {
return $this->targets->removeElement($target);
}
foreach ($this->targets as $t) {
if ($t->getId() == $target) {
return $this->targets->removeElement($t);
}
}
return $this;
}
This would mean you don't have to perform the second query manually as doctrine will know it needs to pull the data on that reference when you iterate over it. Then you can make this operation quicker by using the prime(true) call to make it pull the information it needs in one call rather than doing it dynamically when you request the object.