Full circle nestable js structure to flat array and back to nested.

parse_nestable.php

<?php 
$json = '[{
	"id": 8,
	"text": 8,
	"children": [{
			"id": 3,
			"text": 3,
			"children": [{
					"id": 1,
					"text": 1,
					"children": []
				}, {
					"id": 6,
					"text": 6,
					"children": [{
							"id": 4,
							"text": 4,
							"children": []
						}, {
							"id": 7,
							"text": 7,
							"children": []
						}
					]
				}
			]
		}, {
			"id": 10,
			"text": 10,
			"children": [{
					"id": 14,
					"text": 14,
					"children": [{
							"id": 13,
							"text": 13,
							"children": []
						}
					]
				}
			]
		}
	]
}]';

// parse json to php array
$list = json_decode($json,true);
pre($list);

// flatten array to add parent and order
$flat = make_flat($list,0);
pre($flat,'flat');

// parse flat array to recreate nested strucure
$nested = make_nested($flat);
pre($nested,'nested');

//convert back to json
echo json_encode($nested);




function make_nested($flat) {
	$nested=[];
	foreach($flat as &$s){
		if($s['parent']==0){
			$nested[] = &$s;
		}else{
			$pid = $s['parent'];
			unset($s['parent']);
			unset($s['order']);
			if(isset($flat[$pid])){
				if (!isset($flat[$pid]['children'])){
					$flat[$pid]['children'] = [];
				}
				$flat[$pid]['children'][] = &$s;
			}
		}
	}
	return $nested;
}

function make_flat($list,$parent){  
	$r=[];     
	foreach($list as $ct => $arr){
		$ct++;
		$r[$arr['id']] = $arr;
		$r[$arr['id']]['parent'] = $parent;
		$r[$arr['id']]['order'] = $ct;
		if(isset($arr['children'])){
			unset($r[$arr['id']]['children']);
			$r = $r + make_flat($arr['children'],$arr['id']);
		}
	}
	return $r;
}

function pre($a,$h=false){
	echo $h ? '<h3 style="margin-bottom: 0px;">'.$h.'</h3><pre style="margin-top: 0px;">' : '<pre style="margin-top: 0px;">';
	print_r($a);
	echo '</pre>';
}

function prex($a,$h=false,$dbg=false){
	pre($a,$h);
	exit;
}

?>

Parent/Child array structure conversion

This converts between single layer (parent notation) and nested (children notation) array structures

flat

Array
(
  [8] => Array
    (
      [id] => 8
      [text] => 8
      [parent] => 0
      [order] => 1
    )

  [3] => Array
    (
      [id] => 3
      [text] => 3
      [parent] => 8
      [order] => 1
    )

  [1] => Array
    (
      [id] => 1
      [text] => 1
      [parent] => 3
      [order] => 1
    )

  [6] => Array
    (
      [id] => 6
      [text] => 6
      [parent] => 3
      [order] => 2
    )

  [4] => Array
    (
      [id] => 4
      [text] => 4
      [parent] => 6
      [order] => 1
    )

  [7] => Array
    (
      [id] => 7
      [text] => 7
      [parent] => 6
      [order] => 2
    )

  [10] => Array
    (
      [id] => 10
      [text] => 10
      [parent] => 8
      [order] => 2
    )

  [14] => Array
    (
      [id] => 14
      [text] => 14
      [parent] => 10
      [order] => 1
    )

  [13] => Array
    (
      [id] => 13
      [text] => 13
      [parent] => 14
      [order] => 1
    )

)

nested

Array
(
  [0] => Array
    (
      [id] => 8
      [text] => 8
      [parent] => 0
      [order] => 1
      [children] => Array
        (
          [0] => Array
            (
              [id] => 3
              [text] => 3
              [children] => Array
                (
                  [0] => Array
                    (
                      [id] => 1
                      [text] => 1
                    )

                  [1] => Array
                    (
                      [id] => 6
                      [text] => 6
                      [children] => Array
                        (
                          [0] => Array
                            (
                              [id] => 4
                              [text] => 4
                            )

                          [1] => Array
                            (
                              [id] => 7
                              [text] => 7
                            )

                        )

                    )

                )

            )

          [1] => Array
            (
              [id] => 10
              [text] => 10
              [children] => Array
                (
                  [0] => Array
                    (
                      [id] => 14
                      [text] => 14
                      [children] => Array
                        (
                          [0] => Array
                            (
                              [id] => 13
                              [text] => 13
                            )

                        )

                    )

                )

            )

        )

    )

)