How to use custom repository methods in Twig template? - symfony

Question

Assuming I have an entity User and an entity Book and they're both joined by User.bookId = Book.id (this marks a user owns a certain book, relation type oneUserToManyBook).
If I now want to execute a performance friendly fetch with Doctrine's DQL or QueryBuilder for all Books a User has read, what is the best way to implement this in a Symfony2/Doctrine2 webapp, so that I can use them in my User loop in a Twig template?
Twig
{% for user in users %}
{{ user.name|e }}
{% for address in user.getAddressesByUserId(user.getId()) %}
{{ address.city }}
{% endfor %}
{% endfor %}
I see two approaches, but both don't lead to my target:
1st approach
Create a custom repository class BookRepository:
public function getBooksOwnedByUser($user_id) {
return $em->createQuery('SELECT b.title
FROM MyBundle\Entity\User u,
MyBundle\Entity\Book b
WHERE u.book_id = b.id'
AND u.id = :user_id)
->setParameter('user_id', $user_id)
->getResult();
}
Problem: Works fine, but I cant call getBooksOwnedByUser() in my Twig template (because it's not tied to the entity User, but to it's repository, which is a subclass of Doctrine\ORM\EntityRepository.
2nd approach
Execute the same query as above - not in my UserRepository, but directly in my User entity class.
Problem here: I could call this method in my Twig template, but I cannot (and should not) use the EntityManager in my User entity class.

Answer 1

It's best if you make a relationship from User to Books. Assuming you have made this relationship you can make your query like this:
public function getBooksOwnedByUser($user_id) {
return $em->createQuery('SELECT u, b
FROM MyBundle\Entity\User u
JOIN u.books b
WHERE u.id = :user_id')
->setParameter('user_id', $user_id)
->getResult();
}
Then in your controller:
$em = $this->getDoctrine()->getManager();
$user_with_books = $em->getRepository('MyBundle\Entity\User')
->getBooksOwnedByUser($user->getId());
return $this->render('YourTemplate.html.twig', array(
'user_with_books' => $user_with_books,
));
In twig:
{% for book in user.books %}
{{ book.title }}
{% endfor %}
Some considerations:
For multiple users you will have to change the query (lazy loading is possible but not advised).
If it's a lot of data you can get a performance boost by getting a scalar result (Array)
If you need different queries for the user that can not be combined you will have to store different variables (objects or arrays). That's why I named it "user_with_books". But if you only have this user in your template you can just as well call it "user".
user.getAddressesByUserId(user.getId()) <-- passing data from one model to query is the responsiblity of the controller (or a service). Best practice is to avoid doing this in your template.
So the answer:
You can not do anything with a custom repository method because it's a function. A function on itself doesn't represent any data. So this is a way you can retrieve the actual data with that function and display that.