Recursively traverse array and merge selected child key into parent - php

Question

I have this array where I check if the child as a particular key ("hidden") is true. When it is, I need to append the node's id to the parent's key "contentId".
I have this which does the job but only for the first item in an array. I suspect the recursion is somehow broken by the return statement. Any ideas? Perhaps I'm missing out on a array_walk_recursive solution?
function bubbleUp(&$tree){
for ($i=0; $i < count($tree); $i++){
if ( isset($tree[$i]['children']) && is_array($tree[$i]['children']) ) {
$tree[$i]['contentId'] = [ $tree[$i]['id'] ];
array_push($tree[$i]['contentId'], bubbleUp($tree[$i]['children']));
} else {
return reportBack($tree[$i]);
}
}
return $tree;
}
function reportBack($node){
if ( $node['hidden'] ) {
return $node['id'];
} else {
return '';
}
}
$tree = [
[
"name" => "Intro",
"id" => 123,
"hidden" => false,
"children" => [[
"name" => "foo",
"id" => 452,
"hidden" => true,
"children" => [
[
"name" => "bar",
"id" => 982,
"hidden" => true,
],
[
"name" => "gru",
"id" => 239,
"hidden" => true,
]
]
]]
]
];
bubbleUp($tree);
echo '<pre><small>'; print_r($tree); echo '</small></pre>';
The end result is meant to be:
$tree = [
[
"name" => "Intro",
"id" => 123,
"hidden" => false,
"children" => [[
"name" => "foo",
"id" => 452,
"hidden" => true,
"children" => [
[
"name" => "bar",
"id" => 982,
"hidden" => true,
],
[
"name" => "gru",
"id" => 239,
"hidden" => true,
]
],
"contentId" => [452, 982, 239]
]],
"contentId" => [123, 452, 982, 239]
]
];

Answer 1

About to head home from work, so i'll try and return to this when I get home, but I tried an array_walk solution, had a fair bit of fun trying to do it in the process. Although I don't believe it's working exactly as you want it just yet, but it may act as a guide for anyone else who looks over the question prior to me getting home.
function recursiveSearch(&$value) {
if (isset($value['children'])) {
foreach ($value['children'] as &$child) {
$id = recursiveSearch($child);
$value['contentID'][] = $id;
}
} else {
if (isset($value['hidden']) && $value['hidden'] == true) {
return $value['id'];
}
}
}
array_walk($tree, 'recursiveSearch');
To re-iterate, this solution is not yet complete, but I have to travel home from work and this may help someone else answer, or if not remind me when I get home to come back to this :p
Here's a link to it in action so far: https://ideone.com/RHql33
Main part that makes this difficult is that you want the content ID to be appended to different places dependent on the parents access level.
I.e. if the parent is false, then the immediate node should append the content ID in that branch, but all sub-nodes below it should also append to that location. (Hopefully that makes sense, i'm terrible at talking about this sort of stuff haha o_o)

Answer 2

Thanks to Virtual Pigeon's answer, which led to this:
function recursiveSearch(&$value) {
$value['contentID'][] = $value['id'];
if (isset($value['children'])) {
foreach ($value['children'] as &$child) {
$id = recursiveSearch($child);
if ( is_array($id) ) {
$value['contentID'] = array_merge($value['contentID'], $id);
} else {
$value['contentID'][] = $id;
}
}
return $value['contentID'];
} else {
if (isset($value['hidden']) && $value['hidden'] == true) {
return $value['id'];
}
}
}