recursive function transform nested array - php

Question

Im my laravel project I have this nested array that needs to be updated (transformed - for the frontend):
array:2 [
0 => array:3 [
"entity_id" => 931
"entity" => "user"
"children" => array:2 [
0 => array:2 [
"entity_id" => 5
"entity" => "location"
]
1 => array:2 [
"entity_id" => 932
"entity" => "user"
]
]
]
1 => array:2 [
"entity_id" => 486
"entity" => "user"
]
]
EXPECTED ARRAY:
array:2 [
0 => array:4 [
"id" => 931
"text" => "Test User 1"
"type" => "user"
"children" => array:2 [
0 => array:3 [
"id" => 5
"text" => "Location 1"
"type" => "location"
]
1 => array:3 [
"id" => 932
"text" => "Test User 2"
"type" => "user"
]
]
]
1 => array:3 [
"id" => 486
"text" => "Test User 3"
"type" => "user"
]
]
I have created a recursive function for this job
public function getNewStructure($tree, &$output) {
foreach($tree as $data) {
$output[] = array(
'id' => $data['entity_id'],
'text' => $data['user'] === 'user' ? User::find($data['entity_id'])->name : Location::find($data['entity_id'])->name,
'type' => $data['entity']
);
$this->getNewStructure($data['children'] ?? [], $output);
}
return $output;
}
but it not returns as expected:
array:4 [
0 => array:3 [
"id" => 931
"text" => "Test User 1"
"type" => "user"
]
0 => array:3 [
"id" => 5
"text" => "Location 1"
"type" => "location"
]
1 => array:3 [
"id" => 932
"text" => "Test User 2"
"type" => "user"
]
1 => array:3 [
"id" => 486
"text" => "Test User 3"
"type" => "user"
]
]
How can I add the children to the $output array in the recursive function ???
I have tried by adding the children key:
$this->getNewStructure($data['children'] ?? [], $output['children']);
as when iterating again it will push the current array in the right place.... but is not working...

Answer 1

I fixed
public function getNewStructure($tree, &$output) {
foreach($tree as $data) {
$element = array(
'id' => $data['entity_id'],
'text' => $data['user'] === 'user' ? User::find($data['entity_id'])->name : Location::find($data['entity_id'])->name,
'type' => $data['entity']
);
if(is_array($data['children']) && count($data['children']) > 0) {
$element['children'] = $this->getNewStructure($data['children'], $element['children']);
}
$output[] = $element;
}
return $output;
}