之前写过同样功能的，使用的递归，代码丑陋不堪，偶然发现写的非常好的实现，摘抄如下：

直接上代码

/**

* 把返回的数据集转换成Tree

* @param array $list 要转换的数据集

* @param string $pid parent标记字段

* @param string $level level标记字段

* @return array

*/

function List2Tree($list, $pk='id', $pid = 'pid', $child = '_child', $root = 0) {

if (!is_array($list)) {

return [];

}

// 创建基于主键的数组引用

$aRefer = [];

foreach ($list as $key => $data) {

$aRefer[$data[$pk]] = & $list[$key];

}

foreach ($list as $key => $data) {

// 判断是否存在parent

$parentId = $data[$pid];

if ($root === $parentId) {

$tree[] = & $list[$key];

} else {

if (isset($aRefer[$parentId])) {

$parent = & $aRefer[$parentId];

$parent[$child][] = & $list[$key];

}

}

}

return $tree;

}

/**

* 把返回的数据集转换成Tree

* @param array $rows 要转换的数据集

* @param string $id 主键id

* @param string $pid parent标记字段

* @param string $child 子节点存放的位置

* @return array

*/

function List2Tree2($rows, $id='id', $pid='pid', $child = 'child') {

$items = array();

foreach ($rows as $row) {

$items[$row[$id]] = $row;

}

foreach ($items as $item) {

$items[$item[$pid]][$child][$item[$id]] = &$items[$item[$id]];

}

return isset($items[0][$child]) ? $items[0][$child] : [];

}

上测试代码

$aData = [

[

"id" => 1,

"pid" => 0,

"name" => "全部分类",

],

[

"id" => 2,

"pid" => 1,

"name" => "电商",

],

[

"id" => 3,

"pid" => 1,

"name" => "社区",

],

[

"id" => 4,

"pid" => 2,

"name" => "订单",

],

[

"id" => 5,

"pid" => 2,

"name" => "产品",

],

[

"id" => 6,

"pid" => 4,

"name" => "下单",

],

];

$aRoot = List2Tree($aData, 'id', 'pid', 'child', 0);

echo json_encode($aRoot) . "\n";

echo "##################\n";

$aRoot = List2Tree2($aData);

echo json_encode($aRoot) . "\n";