Sort Childobjects by specific value - typo3

Question

im currently trying to sort all Childobjects i can get by their validity time.
my current code is not sorting anything:
$children = $this->productRepository->findByParent($product->getNumber());
foreach ($children as $child) {
//debug::debug($child->getvalidityPeriod());
$product->addChild($child);
}
As allready to see in the debug, $child->getvalidityPeriod() is there to get the needed info as integer. I thought, there must be a way to sort this object array by their validityPeriod, but how do i manage that? Do i need to create a new method and filter it there or can i use something BEFORE the ForEach Loop?
Pseudo like:
$children = $this->productRepository->findByParent($product->getNumber());
ObjectSortFunction($children, 'getvalidityPeriod');
...and then for each...
Would be awesome if somebody would help me!

Answer 1

Okay after several tries i have a workaround, that can be used as answer, as well ;)
I wrote this method in my repo:
public function findByParentSorted($parentId)
{
$query = $this->createQuery();
$query->matching($query->equals('parent', $parentId));
$query->setOrderings(
[
'validity_period' => \TYPO3\CMS\Extbase\Persistence\QueryInterface::ORDER_ASCENDING
]
);
return $query->execute();
}