Doctrine OneToMany 关系的问题

Question

I have an issue with the doctrine relationship. I try different ways but anything won't work. Idea is that I have a News entity and every news should have many comments. So I try next:

The News entity:

/**
 * @ORM\OneToMany(targetEntity="App\ORM\Entity\NewsComment", mappedBy="news")
 */
protected \Doctrine\Common\Collections\Collection $comments;

/**
 * News constructor.
 */
public function __construct() {
    $this->comments = new ArrayCollection();
}

And NewsComment entity:

/**
 * @ORM\ManyToOne(targetEntity="App\ORM\Entity\News", inversedBy="comments")
 */
protected \App\ORM\Entity\News $news;

Every entity has its own get and set methods as well.

But, when I receive a News entity a can get comments collection but it always empty. On the other hand, I can take any NewsComment entity and get from this News entity. It is working fine. But not to another way.

Is anything wrong with my code?

Answer 1

Doctrine sets owned (non-inversed) collection as lazy by default.
When retrieving an entity by database, you should see an empty PersistentCollection instead of ArrayCollection , with initialized property set to false.

When calling any method on that collection, doctrine fires the queries needed to initialize the collection and populate it.

Collection emptiness should be only checked invoking isEmpty .