How to optimize number of Doctrine queries when using an inner Join? - php

Question

I have to simple Entity: Log and User.
Log has a ManyToOne relationship with Entity.
Log:
type: entity
repositoryClass: LogRepository
id:
id:
type: integer
generator:
strategy: AUTO
fields:
message:
type: string
manyToOne:
user:
targetEntity: User
joinColumns:
user_id:
referencedColumnName: id
My use case is to show the list of the logs and one or two information about the user (like his name and his mail for example)
If I use the findall method, Symfony debug toolbar shows me that Doctrine performs a lot of queries. One query gives me the logs and one query is performed for each user! It is not good of course because I can have thousand logs in my view. I don't want to overload my database server. This problem seems very simple to solve. But I'm searching for a while and the results seems to be "bad practices".
So I began by writing a new method in the LogRepository class using the querybuilder:
public function getLog(){
$qb = $this->createQueryBuilder('l')
->select('l')
->innerJoin(
'ApplicationSonataUserBundle:User', 'u',
Expr\Join::WITH,'l.user = u.id')
;
return $qb->getQuery()->getResult();
}
I still had the same problem. I have changed the select parameters on my method to :
public function getLog(){
$qb = $this->createQueryBuilder('l')
->select('l','u')
->innerJoin('ApplicationSonataUserBundle:User','u',
Expr\Join::WITH,'l.user = u.id')
;
return $qb->getQuery()->getResult();
}
Eureka? OK, I only have one query but my method didn't return only Log, BUT User too... So my Twig template crashes because my loop contains User, not only Log. When this is a User, my view crash because I want to write message fields. (Log.message exists. But User.message is not a valid field, of course)
It works pretty good, if I change one more time my method with a loop to filter my results :
public function getLog(){
$qb = $this->createQueryBuilder('l')
->select('l','u')
->innerJoin('ApplicationSonataUserBundle:User','u',
Expr\Join::WITH,'l.user = u.id')
;
//THE STRANGE LOOP
$results = array();
foreach ($qb->getQuery()->getResult() as $result){
if ($result instanceof Log){
$results[] = $result;
}
};
return $results;
}
I have only one query, it is what I'm searching for. My twig template doesn't crash, because my array contains only Log.
So what's the matter? It works, but I think this is not the good/best practices.
Someone can explain me a better way, a better practice to use an inner join query, to minimize the performed query and have an ArrayCollection result which contains only instance of Log?

Answer 1

It should not be necessary to use the loop. Try like this:
public function getLog(){
$qb = $this->createQueryBuilder('l')
->select('l','u')
->innerJoin('l.user', 'u');
$logs = $qb->getQuery()->getResult();
return $logs;
}
It should only return $logs with a populated (fetch joined) association user.