CODEWITHSUNDEEP
phparrays
Morteza Negahi
Morteza Negahi

Reputation: 3493

How to convert tree array to flat array?

I have a tree-like array and I need to marge or convert it to a flat array but I cannot make it work.

I am trying with this code:

$fakepages = array();
    $fakepages[0] = array('id' => 1, 'parent_id' => 0, 'title' => 'Parent Page');
    $fakepages[1] = array('id' => 2, 'parent_id' => 1, 'title' => 'Sub Page');
    $fakepages[2] = array('id' => 3, 'parent_id' => 2, 'title' => 'Sub Sub Page');
    $fakepages[3] = array('id' => 4, 'parent_id' => 3, 'title' => 'Another Parent Page');
    $fakepages[4] = array('id' => 5, 'parent_id' => 0, 'title' => 'Another Parent Page 5');
    $fakepages[5] = array('id' => 6, 'parent_id' => 2, 'title' => 'Another Parent Page 5');

    $tree = $this->buildTree($fakepages);
    return $tree;

private function buildTree(array $elements, $parentId = 0) {
    $branch = array();

    foreach ($elements as $element) {
        if ($element['parent_id'] == $parentId) {
            $children = $this->buildTree($elements, $element['id']);
            if ($children) {
                $element['children'] = $children;
            }
            $branch[] = $element;
        }
    }

    return $branch;
}

And this is my sort (or merge or ...?) code. What's is the problem with my code and how can I fix this and make it like in the left picture?

private function findchild($trees)
{
    $arr = array();

    foreach ($trees as $tree) {

        if (isset($tree['children'])) {
            $this->mes[] = ['id'=>$tree['id'],'parent_id'=>$tree['parent_id']];
            $arr[] = $this->findchild($tree['children']);
        }
        else{
            $this->mes[] = ['id'=>$tree['id'],'parent_id'=>$tree['parent_id']];
            $arr[] = $tree;
        }
        return $arr;
    }
}
private $mes = [];

I have what is in the right part, but need to convert it to what is in the left part:

enter image description here

Upvotes: 0

Views: 1300

Answers (1)

trincot
trincot

Reputation: 350272

You could use this PHP function, which assumes your data is an array of standard class objects:

function flatten($arr) {
    $result = [];
    foreach($arr as $item) {
        if (isset($item->children))
            $result = array_merge($result, flatten($item->children));
        unset($item->children);
        $result[] = $item;  
    }
    return $result;
}

Of course, if your original value is JSON, you need to first decode it and only then pass it to this function, like this:

$arr = json_decode($json);
// Flatten it
$arr = flatten($arr);
// Optionally sort the result
usort($arr, function($a, $b) { return $a->id - $b->id; });

See it run on eval.in

If your data consists of associative arrays (not "objects"), then, the code needs to use bracket notation instead of ->:

function flatten($arr) {
    $result = [];
    foreach($arr as $item) {
        if (isset($item['children']))
            $result = array_merge($result, flatten($item['children']));
        unset($item['children']);
        $result[] = $item;
    }
    return $result;
}

and the sort:

usort($arr, function($a, $b) { return $a['id'] - $b['id']; });

Upvotes: 3

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