PHPStan: Property with generic class does not specify its types: TKey, T

Question

I'm running PHPStan on a Symfony project where I have the following relation in a Doctrine entity:

/**
 * @ORM\OneToMany(targetEntity="App\Entity\Course\Slide", mappedBy="chapter", cascade={"persist"}, orphanRemoval=true)
 * @ORM\OrderBy({"listOrder" = "ASC"})
 *
 * @var ArrayCollection<Slide>
 */
private $slides;

Running analysis with rule level 6 I got the following message about the property (and its getter return type):

Property App\Entity\Course\Chapter::$slides with generic class Doctrine\Common\Collections\ArrayCollection does not specify its types: TKey, T
💡 You can turn this off by setting checkGenericClassInNonGenericObjectType: false in your phpstan.neon.

My edit attempts only confused PHPStan, maybe because I'm not fully understanding generics here. But silencing the message just because I don't get it would be stupid.

What am I supposed to add or change in the PHPDoc ?

Ermine

Please ask on GitHub next time: github.com/phpstan/phpstan/issues/new/choose – Doggo

@OndřejMirtes I didn't want to bother you on GitHub as it is not a bug, but I'll remember (I often visit your GitHub btw). – Ermine

I treat GitHub issues as a support inbox, so it's fine :) – Doggo

Answer 1

ArrayCollection has two type variables:

• The type of the key (TKey)
• The type of the value (T).

So ArrayCollection<Slide> isn't sufficient, you need something like ArrayCollection<int, Slide>.

Intyre

Thank you. I think I understand, but just to be sure: the int type represents the foreign key type ? – Ermine

I'm not sure what Doctrine puts there as the iterable key type, you should try it out. – Doggo

Don't forget the space between coma and Slide! I lost one hour because of this space ^^ – Rabbinical

Answer 2

It's

/**
 * @var ArrayCollection<int, Slide>
 */

Doing dump() on the parent entity shows that $slides is a 0-indexed array:

0 => App\Entity\Slide
1 => App\Entity\Slide

So it's an int, but not the entity's ID (since it isn't persisted yet).

Here's an in-depth article on generics by Ondřej Mirtes (=author of PhpStan): https://medium.com/@ondrejmirtes/generics-in-php-using-phpdocs-14e7301953

Middlebrow

Thank you, I get it now. I have tried to read this post in the past but did not understand, now it clicks ! Going to refactor some code with generics – Ermine

Answer 3

I ran into the issue that all these didnt work (nor their multi-line version):

/** @var Collection<int, Note> */
/** @var Collection<int, Note> $notes */
/** @var $notes Collection<int, Note> */

My preliminairy conclusion is that in my project (php8+) I dont have an Annotation reader because my whole project is Attribute based.

My Solution:.

1. I installed this extension:

   composer require --dev php-static-analysis/phpstan-extension
   

2. Added this to my phpstan.neon:

   includes:
       - vendor/php-static-analysis/phpstan-extension/extension.neon
   

3. Used it like so:

   #[Type('Collection<int, Note>')]
   private Collection $notes;
   

More docs: https://github.com/php-static-analysis/phpstan-extension

Ammonic