php function for converting a recursively array to a list in right order

Question

I have an external API that returns a category list:

Current array:

id | parent | name
3  | 6      | Sub
6  | 9      | Test
9  | 0      | Parent 1
2  | 0      | Parent 2

Need to be:

id | parent | name
9  | 0      | Parent 1
2  | 0      | Parent 2
6  | 9      | Test
3  | 6      | Sub

Now I will convert this list in the right order, (from parent to childs), so I can simple foreach this new array and insert it in my database (with my custom parent_id).

I have created a function, but this works not good:

// DOES NOT WORK!!
function sortArrayFromParentToChilds($array)
{
    $output = [];
    foreach ($array as $key => $a) {

        // search in new array
        if (empty($output)) {
            $output[] = $a;
            unset($array[$key]);
        } else {

            if (findSubCategory($a, $output)) {
                array_push($output, $a);
            } else {
                array_unshift($output, $a);
            }
            unset($array[$key]);
        }


    }
    return $output;
}
function findSubCategory($id, $output)
{
    foreach ($output as $o) {
        if ($o['parent'] == $id) {
            return true;
        }
    }
    return false;
}

$result = sortArrayFromParentToChilds($initial);

Who can help me to get this function working?

Updated: added some sample data:

$initial = array(
    array(
        'name' => 'Paul',
        'id' => 4,
        'parent' => 2
    ),
    array(
        'name' => 'Liz',
        'id' => 5,
        'parent' => 2
    ),
    array(
        'name' => 'Comus',
        'id' => 6,
        'parent' => 3
    ),
    array(
        'name' => 'Mai',
        'id' => 7,
        'parent' => 2
    ),
    array(
        'name' => 'Titus',
        'id' => 8,
        'parent' => 3
    ),
    array(
        'name' => 'Adult',
        'id' => 9,
        'parent' => 6
    ),
    array(
        'name' => 'People',
        'id' => 2,
        'parent' => 0
    ),
    array(
        'name' => 'Puppy',
        'id' => 10,
        'parent' => 8
    ),
    array(
        'name' => 'Programmers',
        'id' => 11,
        'parent' => 4
    ),
);

What should the resulting array look like and what is the result of your function? — AbraCadaver
– AbraCadaver, Commented May 19, 2021 at 14:56
If the only purpose of reordering is to insert it in a specific order in the database, there is no need for it. You can always retrieve from the database with ORDER BY — Michel
– Michel, Commented May 19, 2021 at 15:21
The "array" shown doesn't look like an array. Can you show it as it appears in code, or with var_export, please? — ggorlen
– ggorlen, Commented May 19, 2021 at 15:38

jspit · Accepted Answer · 2021-05-20 01:02:21Z

1

This solution looks for all elements that have no parents, stores them in the $sortArray and deletes them in $data.

$data = $initial;

$sortData = [];
while(count($data)){
  $ids = array_column($data,'id');
  foreach($data as $key => $row){
    if(in_array($row['parent'],$ids)) continue;
    $sortData[] = $row;
    unset($data[$key]);
  }
}

echo '<pre>';
var_export($sortData);

Output:

array (
  0 => 
  array (
    'name' => 'Comus',
    'id' => 6,
    'parent' => 3,
  ),
  1 => 
  array (
    'name' => 'Titus',
    'id' => 8,
    'parent' => 3,
  ),
  2 => 
  array (
    'name' => 'People',
    'id' => 2,
    'parent' => 0,
  ),
  3 => 
  array (
    'name' => 'Paul',
    'id' => 4,
    'parent' => 2,
  ),
  4 => 
  array (
    'name' => 'Liz',
    'id' => 5,
    'parent' => 2,
  ),
  5 => 
  array (
    'name' => 'Mai',
    'id' => 7,
    'parent' => 2,
  ),
  6 => 
  array (
    'name' => 'Adult',
    'id' => 9,
    'parent' => 6,
  ),
  7 => 
  array (
    'name' => 'Puppy',
    'id' => 10,
    'parent' => 8,
  ),
  8 => 
  array (
    'name' => 'Programmers',
    'id' => 11,
    'parent' => 4,
  ),
)

Note: There must be no elements with id == parent in $data.

answered May 20, 2021 at 1:02

jspit

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1 Comment

angelique000 Over a year ago

This is exactly what I need. Thanks very much!!

cachique · Accepted Answer · 2021-05-19 20:08:36Z

1

This should work.

function orderArray($arr){

    $ordArr = array();
    $parentKeys = array(0); // Top Level elements have 0 in parent field
    $newParentKeys = array();
    $goon = true;

    // search for parentkeys
    while($goon) {
        $goon = false;
        foreach($arr as $row) {
            if (in_array( $row['parent'], $parentKeys)){ // There are kids
                $newParentKeys[] = $row['id']; // future parent key
                $ordArray[] = $row; // add element in order
                $goon = true; // Keep going another level down
            }
        }
        $parentKeys = $newParentKeys; // Update parent keys for the next level
        $newParentKeys = array(); // clear this array

    }

    return $ordArray;
}

edited May 19, 2021 at 20:08

answered May 19, 2021 at 17:53

cachique

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3 Comments

angelique000 Over a year ago

Sorry, it doesn't work. I have add some sample data to my original post, when I insert this data, it doesnt work...

cachique Over a year ago

Id 3 is missing in your sample data. So children of this ID (6, 8) and subsequent children (9, 10) will not be listed. I assumed only parent = 0 to start tree traversal.

jspit Over a year ago

I rated the approach as good. The initial dates were so that only parent == 0 have no parents.

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