平面PHP数组到层次结构树

Question

我有一个包含以下键的数组

id   
parent_id
name

示例数组:

array(7) {
  [0]=>
  array(3) {
    ["id"]=>
    string(1) "4"
    ["parent_id"]=>
    string(1) "0"
    ["name"]=>
    string(16) "Top Level Page 4"
  }
  [1]=>
  array(3) {
    ["id"]=>
    string(1) "5"
    ["parent_id"]=>
    string(1) "1"
    ["name"]=>
    string(19) "Second Level Page 1"
  }
  [2]=>
  array(3) {
    ["id"]=>
    string(1) "6"
    ["parent_id"]=>
    string(1) "2"
    ["name"]=>
    string(19) "Second Level Page 2"
  }
  [3]=>
  array(3) {
    ["id"]=>
    string(1) "7"
    ["parent_id"]=>
    string(1) "5"
    ["name"]=>
    string(18) "Third Level Page 1"
  }
  [4]=>
  array(3) {
    ["id"]=>
    string(1) "3"
    ["parent_id"]=>
    string(1) "0"
    ["name"]=>
    string(16) "Top Level Page 3"
  }
  [5]=>
  array(3) {
    ["id"]=>
    string(1) "2"
    ["parent_id"]=>
    string(1) "0"
    ["name"]=>
    string(16) "Top Level Page 2"
  }
  [6]=>
  array(3) {
    ["id"]=>
    string(1) "1"
    ["parent_id"]=>
    string(1) "0"
    ["name"]=>
    string(16) "Top Level Page 1"
  }
}

我想要做的是使用这个数组显示一个层次结构树,我现在的代码正在产生:

Top Level Page 4
--Second Level Page 1
---Second Level Page 2
----Third Level Page 1
Top Level Page 3
Top Level Page 2
Top Level Page 1

理想情况下,我需要产生以下结果但具有无限级别:

Top Level Page 4
-Second Level Page 1
-Second Level Page 2
--Third Level Page 1
Top Level Page 3
Top Level Page 2
Top Level Page 1

我到目前为止的代码是:

$level = 1;
        foreach ($data as $row) {
            if ($row['parent_id'] == 0) {
                echo $row['name'] . '<br/>';
            } else {
                $level++;
                foreach ($data as $m) {
                    if ($m['parent_id'] === $row['parent_id']) {
                        $c = 0;
                        $append = '';
                        while ($c < $level) {
                            $append.="-";
                            $c++;
                        }
                        echo $append . $row['name'] . '<br/>';
                    }
                }
            }
        }
    }

如果有人能给我一些关于如何实现这一点的指示,我将不胜感激.

我在这里找到了一个解决方案:从PHP数组创建嵌套列表以获取下拉选择字段

Answer 1

你应该使用递归.

这里是代码的例子:

$datas = array(
    array('id' => 1, 'parent' => 0, 'name' => 'Page 1'),
    array('id' => 2, 'parent' => 1, 'name' => 'Page 1.1'),
    array('id' => 3, 'parent' => 2, 'name' => 'Page 1.1.1'),
    array('id' => 4, 'parent' => 3, 'name' => 'Page 1.1.1.1'),
    array('id' => 5, 'parent' => 3, 'name' => 'Page 1.1.1.2'),
    array('id' => 6, 'parent' => 1, 'name' => 'Page 1.2'),
    array('id' => 7, 'parent' => 6, 'name' => 'Page 1.2.1'),
    array('id' => 8, 'parent' => 0, 'name' => 'Page 2'),
    array('id' => 9, 'parent' => 0, 'name' => 'Page 3'),
    array('id' => 10, 'parent' => 9, 'name' => 'Page 3.1'),
    array('id' => 11, 'parent' => 9, 'name' => 'Page 3.2'),
    array('id' => 12, 'parent' => 11, 'name' => 'Page 3.2.1'),
    );

function generatePageTree($datas, $parent = 0, $depth=0){
    $ni=count($datas);
    if($ni === 0 || $depth > 1000) return ''; // Make sure not to have an endless recursion
    $tree = '<ul>';
    for($i=0; $i < $ni; $i++){
        if($datas[$i]['parent'] == $parent){
            $tree .= '<li>';
            $tree .= $datas[$i]['name'];
            $tree .= generatePageTree($datas, $datas[$i]['id'], $depth+1);
            $tree .= '</li>';
        }
    }
    $tree .= '</ul>';
    return $tree;
}

echo(generatePageTree($datas));

您可以在http://phpfiddle.org/main/code/1qy-5fj进行测试

或者,如果您想要确切的格式:

function generatePageTree($datas, $parent = 0, $depth = 0){
    $ni=count($datas);
    if($ni === 0 || $depth > 1000) return ''; // Make sure not to have an endless recursion
    $tree = '';
    for($i=0; $i < $ni; $i++){
        if($datas[$i]['parent'] == $parent){
            $tree .= str_repeat('-', $depth);
            $tree .= $datas[$i]['name'] . '<br/>';
            $tree .= generatePageTree($datas, $datas[$i]['id'], $depth+1);
        }
    }
    return $tree;
}

测试:http://phpfiddle.org/main/code/jw3-s1j

Answer 2

您可以使用Gears 帮助程序库中的FlatToTreeConverter 类：

<?php
namespace Cosmologist\Gears\Collection;
/**
 * Class able to convert a flat array with parent ID's to a nested tree
 */
class FlatToTreeConverter
{
    /**
     * Convert a flat array with parent ID's to a nested tree
     *
     * @link http://blog.tekerson.com/2009/03/03/converting-a-flat-array-with-parent-ids-to-a-nested-tree/
     *
     * @param array  $array           Flat array
     * @param string $idKeyName       Key name for the element containing the item ID
     * @param string $parentIdKey     Key name for the element containing the parent item ID
     * @param string $childNodesField Key name for the element for placement children
     *
     * @return array
     */
    public static function convert(array $array, $idKeyName = 'id', $parentIdKey = 'parentId', $childNodesField = 'children')
    {
        $indexed = array();
        // first pass - get the array indexed by the primary id
        foreach ($array as $row) {
            $indexed[$row[$idKeyName]]                   = $row;
            $indexed[$row[$idKeyName]][$childNodesField] = array();
        }
        // second pass
        $root = array();
        foreach ($indexed as $id => $row) {
            $indexed[$row[$parentIdKey]][$childNodesField][$id] = &$indexed[$id];
            if (!$row[$parentIdKey]) {
                $root[$id] = &$indexed[$id];
            }
        }
        return $root;
    }
}