Creating a nested array form a flat array trough Parent ID - php

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 ();
);
}

Answer 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);
?>

Answer 2

/**
* 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;
}