2022-08-23-add-generics-to-collections.md

title	issue
Add generics to collections	NEXT-15740

Core

• Changed \Shopware\Core\Framework\Struct\Collection to allow specifying the generic type of the collection and using that type as return type were applicable.
• Changed all classes extending from \Shopware\Core\Framework\Struct\Collection to specify the generic type of the collection.
• Added \Shopware\Core\DevOps\StaticAnalyze\PHPStan\Type\CollectionHasSpecifyingExtension to improve static analysis of collections.

---

Upgrade information

Generics for collections

Collection classes now support to specify the concrete type of the elements inside the collection via phpstan generics.

/**
 * @extends Collection<DummyElement>
 */
class DummyCollection extends Collection

This will give you way better phpstan type coverage for the collections. With the help of generics phpstan now also understands that if count on a collection and the return is greater than 0 that first() and last() will never return null.

if ($collection->count() > 0) {
    // phpstan knows that $entity is never null
    $entity = $collection->first();
}

if (\count($collection) === 0) {
    return;
}
// phpstan knows that $entity is never null
$entity = $collection->first();

static::assertCount(2, $collection);
// phpstan knows that $entity is never null
$entity = $collection->first();

Similarly, phpstan knows that after you called has() with a specific key, that get() with the same key will never return null.

if ($collection->has('foo')) {
    // phpstan knows that $entity is never null
    $entity = $collection->get('foo');
}

static::assertTrue($collection->has('foo'));
// phpstan knows that $entity is never null
$entity = $collection->get('foo');