Converting a flat array to a specific array format - php

Question

Fellow PHP programmers, consider the following DB result:
+---------+-----------+---------------+--------+
| node_id | parent_id | path | branch |
+---------+-----------+---------------+--------+
| 1 | 0 | /1/ | NULL |
| 2 | 1 | /1/2/ | NULL |
| 3 | 2 | /1/2/3/ | 1 |
| 4 | 3 | /1/2/3/4/ | 1 |
| 8 | 4 | /1/2/3/4/8/ | 1 |
| 9 | 8 | /1/2/3/4/8/9/ | 1 |
| 7 | 4 | /1/2/3/4/7/ | 0 |
| 5 | 2 | /1/2/5/ | 0 |
| 6 | 5 | /1/2/5/6/ | 0 |
+---------+-----------+---------------+--------+
How does one get the following PHP array:
[
[
'id' => 1,
'parentId' => 0,
],
[
'id' => 2,
'parentId' => 1,
'nodes' => [
[ // when branch == 0
[
'id' => 5,
'parentId' => 2
],
[
'id' => 6,
'parentId' => 5
],
],
[ // when branch == 1
[
'id' => 3,
'parentId' => 2
],
[
'id' => 4,
'parentId' => 3,
'nodes' => [
[ // when branch == 0
[
'id' => 7,
'parentId' => 4
],
],
[ // when branch == 1
[
'id' => 8,
'parentId' => 4
],
[
'id' => 9,
'parentId' => 8
],
]
]
],
]
]
]
]
The function should work with unlimited depth.
Any help would be greatly appreciated as I've been hitting a wall.

Answer 1

Something like this:
function buildTree($arr, $parentID)
{
$children = [];
foreach ($arr as $item) {
if ($item['parent_id'] == $parentID) {
array_push($children, [
'id' => $item['node_id'],
'parentId' => $item['parent_id'],
'nodes' => buildTree($arr, $item['node_id'])
]);
}
}
return $children;
}
$tree = buildTree($flat, null);
UPD:
function getBranches($arr, $parentID)
{
$branches = array();
foreach ($arr as $item) {
if ($item['parent_id'] == $parentID) {
$bKey = $item['branch'];
$node = array(
'id' => $item['node_id'],
'parentId' => $item['parent_id']
);
$firstNodeChild = false;
if ($nodeChildren = getBranches($arr, $item['node_id'])) {
$hasKey = array_key_exists($bKey, $nodeChildren);
if ($hasKey && $nodeChildren[$bKey]) {
if (sizeof($nodeChildren[$bKey]) == 1) {
$firstNodeChild = $nodeChildren[$bKey][0];
unset($nodeChildren[$bKey]);
}
}
if ($nodeChildren) {
$node['nodes'] = $nodeChildren;
}
}
if (!array_key_exists($bKey, $branches)) {
$branches[$bKey] = array();
}
$branches[$bKey][] = $node;
if (false !== $firstNodeChild) {
$branches[$bKey][] = $firstNodeChild;
}
}
}
ksort($branches);
return $branches;
}
$tree = getBranches($arr, 0);