Doctrine / Symfony 一对多关系中 getSomethings 的返回值是什么？

Question

I like to either type-hint or starting in PHP7 actually show the return value of a getter function. But with One-To-Many relationships in Doctrine / Symfony, I'm still stuck and am not sure what to add to the @var tag.

[...]

/**
 * @var string
 * @ORM\Column(name="name", type="string")
 */
private $features;


/**
 * What goes into var here?
 *
 * One Product has Many Features.
 * @ORM\OneToMany(targetEntity="Feature", mappedBy="product")
 */
private $features;

public function __construct()
{
    $this->features = new ArrayCollection();
    $this->name = 'New Product Name';
}

/**
 * @return Collection
 */
public function getFeatures(): Collection
{
    return $this->features;
}


[...]

Currently I'm using @var Collection and can then use the Collection functions. But what would be the »proper« thing to return? Is it indeed Collection ? Or is it ArrayCollection ? I'm tempted to use Features[] in order to use the functions of Feature, if I need to (instead of typehinting), but it doesn't feel right.

What would be the »cleanest« / stable way to do this?

Answer 1

If you want to keep the docblock I would use the union type | to both specify the Collection and the list of values it contains like:

/**
 * @var Collection|Feature[]
 */

With this your IDE should both find the methods from Collection as well as the Feature-type hints when you get a single object from the collection, eg in a foreach.

As to the question of ArrayCollection vs. Collection, it is usually recommended to type hint for the interface (Collection in this case). ArrayCollection offers a few more methods, but unless you really need them I would not bother with the type hint just to get them.

What I tend to do in projects is keep the Collection inside the entity and only pass out an array in the getter like this:

public function getFeatures(): array
{
    return $this->features->toArray();
}

public function setFeatures(array $features): void
{
    $this->features = new ArrayCollection($features);
}

Be careful, the void return type is not supported in PHP 7.0 yet. The benefit of returning an array is that in your code you don't have to worry about what kind of Collection Doctrine uses. That class is mainly used to maintain reference between objects inside Doctrine's Unit Of Work, so it should not really be part of your concern.