values not push on recursive array - php

Question

Let me explain my problem. I try to generate an array of categories.
Here is my function.
private function recursiveCategoriesTree($id_parent, $level, $categories)
{
$tree = array();
foreach($categories as $categorie)
{
if($id_parent == $categorie['id_parent'])
{
$tree[$level][] = $categorie;
$this->recursiveCategoriesTree($categorie['id_category'], ($level+1), $categories);
}
}
return $tree;
}
When I trace the loop with echo, everything seems to work, all the parent categories and girls are covered, but are not pushed into the array.
Here is the print_r of my categories
array(
[0] => Array
(
[id_category] => 4
[name] => Pièces détachées
[id_parent] => 1
)
[1] => Array
(
[id_category] => 5
[name] => Excavateur
[id_parent] => 4
)
[2] => Array
(
[id_category] => 6
[name] => série 100
[id_parent] => 5
)
[3] => Array
(
[id_category] => 7
[name] => above
[id_parent] => 6
)
[4] => Array
(
[id_category] => 8
[name] => système hydraulique
[id_parent] => 7
)
[5] => Array
(
[id_category] => 9
[name] => série 200
[id_parent] => 5
)
[6] => Array
(
[id_category] => 10
[name] => thru
[id_parent] => 6
)
[7] => Array
(
[id_category] => 11
[name] => Compaction
[id_parent] => 4
)
)
Here is the result of print_r generated
Array(
[0] => Array
(
[0] => Array
(
[id_category] => 5
[name] => Excavateur
[id_parent] => 4
)
[1] => Array
(
[id_category] => 11
[name] => Compaction
[id_parent] => 4
)
)
)
I call my function like that
$tree = $this->recursiveCategoriesTree(4, 0, $categories)
What is the problem ? thank you =)

Answer 1

Either get the return value from your recursive call and push that onto the array, or make a private property of the class called tree and push values onto that instead. You are not passing the variable $tree across recursive function calls.
E.g. if you do this it will work: (EDIT: Fixed... [again])
private $catTree = array();
private $catStartLevel = FALSE;
private function recursiveCategoriesTree($id_parent, $level, $categories) {
if ($this->catStartLevel !== FALSE) $this->catStartLevel = $level;
foreach($categories as $categorie) {
if($id_parent == $categorie['id_parent']) {
$this->catTree[$level][] = $categorie;
$this->recursiveCategoriesTree($categorie['id_category'], ($level+1), $categories);
}
}
if ($this->catStartLevel === $level) {
$tree = $this->catTree;
$this->catTree = array();
$this->catStartLevel = FALSE;
}
return $tree;
}
...however this is not great, because you now have a 'pointless' private property in your class. You would be better to change you array structure, and catch the return values from $this->recursiveCategoriesTree()...
EDIT
Thinking about it, if you really want the array in that structure, you would probably be better to pass the variable to be populated with the array by reference:
private function recursiveCategoriesTree($id_parent, $level, $categories, &$tree) {
foreach($categories as $categorie) {
if($id_parent == $categorie['id_parent']) {
$tree[$level][] = $categorie;
$this->recursiveCategoriesTree($categorie['id_category'], ($level+1), $categories, $tree);
}
}
}
...and then you would call it like this...
$myTree = array();
$obj->recursiveCategoriesTree($id_parent, $level, $categories, $myTree);
print_r($myTree);

Answer 2

recursiveCategoriesTree() returns the $tree, but you're not doing anything with that return value when you're calling the method recursively. You're only storing the $tree returned from the initial call to the method.
Perhaps you want something like this?
$categorie['children'] = $this->recursiveCategoriesTree($categorie['id_category'], ($level+1), $categories);

Answer 3

You should first fetch all the childs of a category, and add them to its array, before appending the category to the tree. Kind of like this:
foreach($categories as $categorie)
{
$categorie['childs'] = $this->recursiveCategoriesTree($categorie['id_category'], ($level+1), $categories);
$tree[$level][] = $categorie;
}