Flattening a JSON multi depty array in PHP

Question

Good morning, given the below data structure (in JSON for ease of reading)

[
{
    \"parent\": \"root\",
    \"active\": \"1\",
    \"label\": \"Index\",
            


        

Answer 1

Not very hard:

function flatten(array $array) {
    $branch = [];

    foreach ($array as $item) {
        $children = [];
        if (isset($item['children']) && is_array($item['children'])) {
            $children = flatten($item['children']);
            unset($item['children']);
        }
        $branch = array_merge($branch, [$item], $children);
    }

    return $branch;
}

Answer 2

Easy-peasy

function flatten($items, &$r) {
    foreach($items as $item) {
        $c = isset($item->children) ? $item->children : null;
        unset($item->children);
        $r []= $item;
        if($c)
            flatten($c, $r);
    }
}

flatten(json_decode($json), $r);
print_r($r);

This accumulates results in one single buffer, passed by reference. This is far more efficient than building a whole new array on each iteration, which is basically a variation of the Shlemiel the painter's algorithm.

If you prefer functional approach, you can use generators:

function flatten($items) {
    foreach($items as $item) {
        $c = isset($item->children) ? $item->children : [];
        unset($item->children);
        yield $item;
        foreach(flatten($c) as $child)
            yield $child;
    }
}

foreach(flatten(json_decode($json)) as $item)
    print_r($item);