实现无限级分类的一种常用方法是使用递归。
下面是一个使用递归实现无限级分类的示例代码：
function buildTree($categories, $parentId = 0) {
$tree = array();
foreach ($categories as $category) {
if ($category['parent_id'] == $parentId) {
$children = buildTree($categories, $category['id']);
if ($children) {
$category['children'] = $children;
}
$tree[] = $category;
}
}
return $tree;
}
// 示例数据
$categories = array(
array('id' => 1, 'parent_id' => 0, 'name' => 'Category 1'),
array('id' => 2, 'parent_id' => 0, 'name' => 'Category 2'),
array('id' => 3, 'parent_id' => 1, 'name' => 'Category 1.1'),
array('id' => 4, 'parent_id' => 1, 'name' => 'Category 1.2'),
array('id' => 5, 'parent_id' => 3, 'name' => 'Category 1.1.1'),
array('id' => 6, 'parent_id' => 2, 'name' => 'Category 2.1'),
);
$tree = buildTree($categories);
print_r($tree);
输出结果：
Array
(
[0] => Array
(
[id] => 1
[parent_id] => 0
[name] => Category 1
[children] => Array
(
[0] => Array
(
[id] => 3
[parent_id] => 1
[name] => Category 1.1
[children] => Array
(
[0] => Array
(
[id] => 5
[parent_id] => 3
[name] => Category 1.1.1
)
)
)
[1] => Array
(
[id] => 4
[parent_id] => 1
[name] => Category 1.2
)
)
)
[1] => Array
(
[id] => 2
[parent_id] => 0
[name] => Category 2
[children] => Array
(
[0] => Array
(
[id] => 6
[parent_id] => 2
[name] => Category 2.1
)
)
)
)
上述代码中，buildTree 函数接收一个包含分类数据的数组和一个指定的父分类ID。它通过遍历分类数组，找到所有指定父分类ID的子分类，并用递归的方式继续遍历子分类的子分类，最终构建出一个无限级分类的树形结构。
这样，你就可以方便地使用这个树形结构来展示无限级分类的数据。
