Creating a nested array form a flat array trough Parent ID

Question

I want to make my flat array to a nested array but I can't seem to do this ;/

the code that I tryed to make it nested with:

<?php
$link = mysqli_connect("localhost", "db_phpnav", "jeXS9ftZhmJdzRWd", "db_phpNav");
$sql = "SELECT ID, PID, Naam  FROM tb_nav";
$result = mysqli_query($link, $sql);

function convertToTree(array $flat, $idField = 'ID',
                        $parentIdField = 'PID',
                        $childNodesField = 'childNodes') {
    $indexed = array();

    foreach ($flat as $row) {
        $indexed[$row[$idField]] = $row;
        $indexed[$row[$idField]][$childNodesField] = array();
    }


    $root = null;
    foreach ($indexed as $id => $row) {
        $indexed[$row[$parentIdField]][$childNodesField][$id] =& $indexed[$id];
        if (!$row[$parentIdField]) {
            $root = $id;
        }
    }

    return array($root => $indexed[$root]);
}

$rows = array();

while($row = mysqli_fetch_assoc($result)) {
    $rows[] = $row;
}

convertToTree($rows);

?>

the array it gives out. it clearly doesn't do what I intended for.

    array(3) {
  [0]=>
  array(3) {
    ["ID"]=>
    string(1) "2"
    ["PID"]=>
    NULL
    ["Naam"]=>
    string(7) "Contact"
  }
  [1]=>
  array(3) {
    ["ID"]=>
    string(1) "5"
    ["PID"]=>
    string(1) "2"
    ["Naam"]=>
    string(7) "testing"
  }
  [2]=>
  array(3) {
    ["ID"]=>
    string(1) "6"
    ["PID"]=>
    NULL
    ["Naam"]=>
    string(8) "testing2"
  }
}

How do i get the array to be nested nicely? it should look more like this:

[0]=>
  array(3) {
    ["ID"]=>
    string(1) "2"
    ["PID"]=>
    NULL
    ["Naam"]=>
    string(7) "Contact"
      'childNodes' => array(
            2 => array(
                ["ID"]=>
                string(1) "5"
                ["PID"]=>
                string(1) "2"
                ["Naam"]=>
                 string(7) "testing"
                'childNodes' => array ();
   );
  }

it clearly doesn't do what I intended for. What you have there is a nested array. If it isn't what you want, then you need to tell us exactly how the resulting array should look. — Ken Herbert
– Ken Herbert, Commented Jan 9, 2014 at 13:55

Kep · Accepted Answer · 2014-01-09 14:07:40Z

1

Suppose this is (kind of) what you want:

<?PHP
$entries = array();

$entries[] = array("ID" => "2", "PID" => NULL, "Naam" => "Contact");
$entries[] = array("ID" => "5", "PID" => "2", "Naam" => "testing");
$entries[] = array("ID" => "6", "PID" => NULL, "Naam" => "testing2");

function convertToTree($flat, $idField = 'ID', $parentIdField = 'PID', $childNodesField = 'childNodes', $curIdx = NULL)
{
    $indexed = array();

    foreach($flat as $row)
    {
        if ($row[$parentIdField] == $curIdx)
        {
            $indexed[$row[$idField]] = $row;
            $indexed[$row[$idField]]["childNodes"] = convertToTree($flat, $idField, $parentIdField, $childNodesField, $row[$idField]);
        }
    }

    return $indexed;
}

print_r($entries);
$tree = convertToTree($entries);
print_r($tree);
?>

answered Jan 9, 2014 at 14:07

Kep

5,88721 silver badges31 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Ken Herbert Over a year ago

@user2013498 If this solves your problem, please accept the answer by clicking the tick to the left of the answer.

Serhii Vasko · Accepted Answer · 2022-06-24 16:06:43Z

/**
 * Transform array to a nested structure.
 * This gets a little complicated. Basically, we're creating a placeholder in
 * $children to hold the child terms of each parent term. Then we create a
 * reference to that element in the parent term. So nesting happens via magic.
 */
function arrayFlatToNested($array, $idKey = 'ID', $parentIdKey = 'PID', $childrenKey = 'childNodes'): array
{
    $arrayNested = [];
    $children = [];

    foreach ($array as $element) {
        // Create a placeholder for the object's children.
        if (!isset($children[$element[$idKey]])) {
            $children[$element[$idKey]] = [];
        }
        // Create a link to those children.
        $element[$childrenKey] = &$children[$element[$idKey]];

        if (!strlen($element[$parentIdKey])) {
            $arrayNested[] = $element;
        } else {
            // Create a placeholder for the parent.
            if (!isset($children[$element[$parentIdKey]])) {
                $children[$element[$parentIdKey]] = [];
            }
            // Add this object to the parent, even if it doesn't exist yet.
            $children[$element[$parentIdKey]][] = $element;
        }
    }

    return $arrayNested;
}

Collectives™ on Stack Overflow

Creating a nested array form a flat array trough Parent ID

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related