Symfony ArrayCollection vs PersistentCollection

Question

As I understood when you query database by repository you get PersistentCollection and when your working with your entities you get ArrayCollection.

so consider I have o

Answer 1

Short answer:

/**
 * @param Doctrine\Common\Collections\Collection $users
 * @return $this
 */
public function setChildren(Doctrine\Common\Collections\Collection $users)
{
    $this->children = $users;

    return $this;
}

Explanation:

If you look deep into Doctrine Classes you will see the following structure:

Array collection is class that implements interface Collection:

class ArrayCollection implements Collection, Selectable

PersistentCollection is class that extentds AbstractLazyCollection:

final class PersistentCollection extends AbstractLazyCollection implements Selectable

but AbstractLazyCollection implements Collection:

abstract class AbstractLazyCollection implements Collection

So:

Collection is interface, that you should use in method setChildren().

This is because of doctrine use lazy loading - mechanism that allow to load not all properties, but only these, that are needed.

Similar question:

Doctrine manyToMany return PersistentCollection instead of ArrayCollection