Doctrine ODM(mongo) - upsert embeded document if not exist - mongodb

Question

A mongo document exists which links Users and Cars. It contains the following fields:
User.userId
User.cars[]
User.updated
User.created
User.cars is an array of embedded documents. A query needs to be written to only insert a Car to this field if it does not already contain a Car with id $carId
The following query will create a new record each time for $userId and $carId. What it should do is either not insert a new record or update the value for driven.
$qb
->findAndUpdate()
->upsert(true)
->field('userId')->equals($userId)
->field('cars.id')->notEqual($carId)
->field('cars')->addToSet([
'id' => $carId,
'driven' => new \DateTime(),
])
->field('updated')->set(new \DateTime())
->field('created')->setOnInsert(new \DateTime())
->limit(1)
;
return $qb->getQuery()->execute();
Removing notEqual($carId) from the query will always insert the record into User.cars, which is also not desired.
The end result should be that User.cars only contains one record for each carId.

Answer 1

If you don't need to search the array of cars later you could store it as an object instead and use $carId as key:
$qb
->findAndUpdate()
->upsert(true)
->field('userId')->equals($userId)
->field("cars.$carId")->set([
'id' => $carId,
'driven' => new \DateTime(),
])
->field('updated')->set(new \DateTime())
->field('created')->setOnInsert(new \DateTime())
->limit(1)
;
return $qb->getQuery()->execute();
If cars are mapped in the document as EmbedMany you may need to change your collection's strategy to either set or atomicSet (I'd suggest the latter) as otherwise ODM will reindex your array each time it's saved.
Once again, this solution has its downsides which can be considered serious depending on how you want to use your data but it solves the problem in question.
Offhand, ->limit(1) is superfluous as ->findAndUpdate() is making a query run findAndModify command which by its nature operates on single document.