Query field added but not visible in template - php

Question

In my Symfony project I try to append new array key-value pair into the result I am rendering to twig template file.
It has some odd behaviour.
$posts = $this->entityManager->getRepository(Post::class)->getPage($listType, $page, $pageSize);
foreach ($posts['data'] as $post) {
$post['destinationName'] = $this->destinationService->getDestinationName($posts['data']);
}
return $this->render('posts.html.twig', [
'posts' => $posts['data'],
]);
Trough this getPage() method in my controller I get paginated list of my data. Which is working. Than in the foreach() I am appending new key-value pair to that array.
When dumping $posts I get: IMAGE
When dumping $post from foreach, this is the output I get: IMAGE As you can see, the last pair, destinationName is added.
Then when dumping the same result in my twig template I get: IMAGE
As you can see, when template is rendered, it disappears.
My question is, that maybe it's overwritten? But I can not see why. Do I maybe need to append that filed in my query builder? But as I am adding the field after result is rendered, I suppose that should not be the case..
Any hints?
Maybe getDestinationName() will show something:
public function getDestinationName($posts)
{
foreach ($posts as $postsData) {
foreach ($postsData as $post) {
$destinationName = $this->getDestinationDetails(
$post->getDestinationId(),
$post->getAccountTokenId()
);
return $destinationName['full_name'];
}
}
}

Answer 1

It's not a good practice to mixe array with object and then add other stuff.
The best thing you could do is this :
$posts = $this->entityManager->getRepository(Post::class)->getPage($listType, $page, $pageSize);
$destinationNames = [];
foreach ($posts['data'] as $post) {
$destinationNames[$post->getPostId()] = $this->destinationService->getDestinationName($posts['data']);
}
return $this->render('posts.html.twig', [
'posts' => $posts['data'],
'destinationNames' => $destinationNames,
]);
I suppose here that $post->getPostId() is your unique identifier, if not, replace by the right identifier
And in your template you could do something like :
{% for post in posts %}
// do your stuff
{{ destinationNames[post.id] }}
{% endfor %}