如何使用递归 PHP 函数检索树结构中特定父级的所有嵌套子节点？

使用 PHP 设计递归函数检索嵌套子节点

在数据以邻接列表格式存储的情况下，递归函数可以有效检索子节点和孙节点特定父节点的节点。这种方法提供了一个定制的解决方案，用于识别给定父级下面的所有节点。

实现

以下是完成此任务的递归函数的实现：

function fetch_recursive($tree, $parent_id, $parent_found = false, $list = array())
{
    foreach ($tree as $key => $node) {
        if ($parent_found || $key == $parent_id) {
            $row_data = array();
            foreach ($node as $field => $value) {
                if ($field != 'children') {
                    $row_data[$field] = $value;
                }
            }
            $list[] = $row_data;

            if (isset($node['children']) && !empty($node['children'])) {
                $list = array_merge($list, fetch_recursive($node['children'], $parent_id, true));
            }
        } elseif (isset($node['children']) && !empty($node['children'])) {
            $list = array_merge($list, fetch_recursive($node['children'], $parent_id));
        }
    }

    return $list;
}

用法

假设您已经使用单独的函数从数据构建了树结构，您可以利用此用于检索特定父节点的所有子节点和孙节点的递归函数。

例如，如果您有一个结构如下的树：

Array
(
    [1] => Array
        (
            [id] => 1
            [name] => Electronics 
            [parent_id] => 0 
            [children] => Array
                (
                    [2] => Array
                        ( 
                            [id] => 2
                            [name] => Televisions 
                            [parent_id] => 1 
                            [children] => Array
                                (
                                    [4] => Array
                                        (
                                            [id] => 4
                                            [name] => Tube 
                                            [parent_id] => 2
                                            [children] => Array()
                                        )
                                    [5] => Array
                                        (
                                            [id] => 5
                                            [name] => LCD 
                                            [parent_id] => 2
                                            [children] => Array()
                                        )
                                    [6] => Array
                                        (
                                            [id] => 6
                                            [name] => Plasma 
                                            [parent_id] => 2
                                            [children] => Array()
                                        )
                                )
                        )
                    [3] => Array 
                        (
                            [id] => 3
                            [name] => Portable Electronics 
                            [parent_id] => 1
                            [children] => Array
                                (
                                    [7] => Array
                                        (
                                            [id] => 7
                                            [name] => Mp3 Players 
                                            [parent_id] => 3 
                                            [children] => Array
                                                (
                                                    [10] => Array
                                                        (
                                                            [id] => 10
                                                            [name] => Flash 
                                                            [parent_id] => 7
                                                            [children] => Array()
                                                        ) 
                                                )
                                        )
                                    [8] => Array 
                                        (
                                            [id] => 8
                                            [name] => CD Players 
                                            [parent_id] => 3
                                            [children] => Array()
                                        )
                                    [9] => Array 
                                        (
                                            [id] => 9
                                            [name] => 2 Way Radios 
                                            [parent_id] => 3
                                            [children] => Array()
                                        )
                                )
                        )
                )
        )
)

要检索其所有子节点，比如说， ID 为 3 的节点，您可以像这样调用该函数：

$parent_id = 3;
$child_nodes = fetch_recursive($tree, $parent_id);

$child_nodes 变量现在将包含一个包含所有子节点的数组ID为3的节点，如：

Array
(
    [0] => Array
        (
            [id] => 3
            [name] => Portable Electronics
            [parent_id] => 1
        )

    [1] => Array
        (
            [id] => 7
            [name] => Mp3 Players
            [parent_id] => 3
        )

    [2] => Array
        (
            [id] => 10
            [name] => Flash
            [parent_id] => 7
        )

    [3] => Array
        (
            [id] => 8
            [name] => CD Players
            [parent_id] => 3
        )

    [4] => Array
        (
            [id] => 9
            [name] => 2 Way Radios
            [parent_id] => 3
        )

)

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