Sorting array by parent / recurse

I have SQL query that returns:

Array
(
    [0] => stdClass Object
        (
            [id] => 1
            [parent] => 
            [created_at] => 2015
            [updated_at] => 0
            [name] => Strona Główna
            [short] => 
            [content] => 
            [header] => 
            [img] => 
            [visible] => 0
            [position] => 1000
            [top] => 0
            [left] => 0
            [footer] => 0
            [dropdown] => 0
            [chilldren] => 0
            [title] => 
            [description] => 
            [keywords] => 
            [tags] => 
            [redirect] => 
            [js] => 
            [css] => 
            [css_class] => 
            [module] => 
            [lang] => 0
        )

    [1] => stdClass Object
        (
            [id] => 2
            [parent] => 1
            [created_at] => 2015
            [updated_at] => 0
            [name] => Podstrona strony głównej
            [short] => 
            [content] => 
            [header] => 
            [img] => 
            [visible] => 0
            [position] => 1000
            [top] => 0
            [left] => 0
            [footer] => 0
            [dropdown] => 0
            [chilldren] => 0
            [title] => 
            [description] => 
            [keywords] => 
            [tags] => 
            [redirect] => 
            [js] => 
            [css] => 
            [css_class] => 
            [module] => 
            [lang] => 0
        )

    [2] => stdClass Object
        (
            [id] => 3
            [parent] => 
            [created_at] => 2015
            [updated_at] => 2015
            [name] => O nas
            [short] => 
            [content] => 
            [header] => 
            [img] => 
            [visible] => 0
            [position] => 1000
            [top] => 0
            [left] => 0
            [footer] => 0
            [dropdown] => 0
            [chilldren] => 0
            [title] => 
            [description] => 
            [keywords] => 
            [tags] => 
            [redirect] => 
            [js] => 
            [css] => 
            [css_class] => 
            [module] => 
            [lang] => 0
        )

    [3] => stdClass Object
        (
            [id] => 5
            [parent] => 1
            [created_at] => 2015
            [updated_at] => 2015
            [name] => Kolejna podstrona
            [short] => 
            [content] => 
            [header] => 
            [img] => 
            [visible] => 0
            [position] => 1000
            [top] => 0
            [left] => 0
            [footer] => 0
            [dropdown] => 0
            [chilldren] => 0
            [title] => 
            [description] => 
            [keywords] => 
            [tags] => 
            [redirect] => 
            [js] => 
            [css] => 
            [css_class] => 
            [module] => 
            [lang] => 0
        )

    [4] => stdClass Object
        (
            [id] => 6
            [parent] => 3
            [created_at] => 2015
            [updated_at] => 0
            [name] => Kolejna podstrona
            [short] => 
            [content] => 
            [header] => 
            [img] => 
            [visible] => 0
            [position] => 1000
            [top] => 0
            [left] => 0
            [footer] => 0
            [dropdown] => 0
            [chilldren] => 0
            [title] => 
            [description] => 
            [keywords] => 
            [tags] => 
            [redirect] => 
            [js] => 
            [css] => 
            [css_class] => 
            [module] => 
            [lang] => 0
        )

    [5] => stdClass Object
        (
            [id] => 8
            [parent] => 5
            [created_at] => 2015
            [updated_at] => 0
            [name] => tuytuytuyt
            [short] => 
            [content] => 
            [header] => 
            [img] => 
            [visible] => 0
            [position] => 1000
            [top] => 0
            [left] => 0
            [footer] => 0
            [dropdown] => 0
            [chilldren] => 0
            [title] => 
            [description] => 
            [keywords] => 
            [tags] => 
            [redirect] => 
            [js] => 
            [css] => 
            [css_class] => 
            [module] => 
            [lang] => 0
        )

    [6] => stdClass Object
        (
            [id] => 9
            [parent] => 5
            [created_at] => 2015
            [updated_at] => 0
            [name] => fghfhgfh
            [short] => 
            [content] => 
            [header] => 
            [img] => 
            [visible] => 0
            [position] => 1000
            [top] => 0
            [left] => 0
            [footer] => 0
            [dropdown] => 0
            [chilldren] => 0
            [title] => 
            [description] => 
            [keywords] => 
            [tags] => 
            [redirect] => 
            [js] => 
            [css] => 
            [css_class] => 
            [module] => 
            [lang] => 0
        )

)

And I've almost successfully made it to sort. If element has a parent, it creates an array and put children to this element, but there's a problem with last elements and I dunno why.

Now output looks like this:

As you can see last elements are not filtered.

Code for "sorting" parent's looks like:

            $new = [];
            foreach($data as $key => $item) {
              $data[$key] - > node = [];
              array_push($new, $data[$key]);

              for ($i = 0; $i < count($new); $i++) {
                if ($new[$i] - > id == $data[$key] - > parent) {
                  array_push($new[$i] - > node, $data[$key]);
                }

              }
            }

            print_r($data);

Can anyone explain to me what am I doing wrong?

Solution

You can use a recursive function, like this:

function makeTree($data, $parent) {
    $tree = [];
    foreach($data as $item) {
        if ($item -> parent == $parent) {
            $item -> node = makeTree($data, $item -> id);
            $tree[] = $item;
        }
    }
    return $tree;
}

$new = makeTree($data, null);

print_r($new);

This function makes a tree of all descendants of the given parent. The recursion stops when an element has no children, and then the function returns an empty array.

The return value of the function (an array) is used by the caller, to add it to the node property of the parent node.

The function is called first by the root value, i.e. the value you assign to the parent property when there is no parent. In your case is this is null, so that is why the main call has null as second argument.