php - 从多维数组创建嵌套列表

Question

我在 PHP 中有一个数组，如下所示：

array (
    [0] => array (
        [id] => 1
        [title] => "Title 1"
        [parent_id] => NULL
        [depth] => 0
    )
    [1] => array (
        [id] => 2
        [title] => "Title 2"
        [parent_id] => NULL
        [depth] => 0
    )
    [2] => array (
        [id] => 3
        [title] => "Title 3"
        [parent_id] => 2
        [depth] => 1
    )
    [3] => array (
        [id] => 4
        [title] => "Title 4"
        [parent_id] => 2
        [depth] => 1
    )
    [4] => array (
        [id] => 5
        [title] => "Title 5"
        [parent_id] => NULL
        [depth] => 0
    )
    [5] => array (
        [id] => 6
        [title] => "Title 6"
        [parent_id] => 4
        [depth] => 2
    )
)

我想要做的是遍历这个数组并<ol>从中创建一个嵌套列表。所以结果应该是这样的：

<ol>
    <li>Title 1</li> // id = 1
    <li>Title 2</li> // id = 2
    <ol>
        <li>Title 3</li> // id = 3 -> parent_id = 2
        <li>Title 4</li> // id = 4 -> parent_id = 2
        <ol>
            <li>Title 6</li> // id = 6 -> parent_id = 4
        </ol>
    </ol>
    <li>Title 5</li> // id = 5
</ol>

我一直在想一种方法来完成这项工作。但到目前为止，每一次尝试都失败了……

任何人都知道我如何<ol>从这样的数组创建这样一个嵌套列表？

请注意，我对给定的数据没有任何控制权。我只是调用一个 API，它返回 json 数据，我将其转换为一个数组。该阵列看起来与我描述的完全一样。

Answer 1

你应该使用递归：

首先是 'php' 语法中的数组：

<?php
$a=array (
    '0' => array (
        'id' => 1,
        'title' => "Title 1",
        'parent_id' => 'NULL',
        'depth' => 0
    ),
    '1' => array (
        'id' => 2,
        'title' => "Title 2",
        'parent_id' => 'NULL',
        'depth' => 0
    ),
    '2' => array (
        'id' => 3,
        'title' => "Title 3",
        'parent_id' => 2,
        'depth' => 1
    ),
    '3' => array (
        'id' => 4,
        'title' => "Title 4",
        'parent_id' => 2,
        'depth' => 1
    ),
    '4' => array (
        'id' => 5,
        'title' => "Title 5",
        'parent_id' => 'NULL',
        'depth' => 0
    ),
    '5' => array (
        'id' => 6,
        'title' => "Title 6",
        'parent_id' => 4,
        'depth' => 0
    )
);

这里的代码：

$level = 'NULL';

function r( $a, $level) {
   $r = "<ol>";
   foreach ( $a as $i ) {
       if ($i['parent_id'] == $level ) {
          $r = $r . "<li>" . $i['title'] . r( $a, $i['id'] ) . "</li>";
       }
   }
   $r = $r . "</ol>";
   return $r;
}

print r( $a, $level );

?>

结果：_

<ol><li>Title 1<ol></ol></li><li>Title 2<ol><li>Title 3<ol>
</ol></li><li>Title 4<ol><li>Title 6<ol></ol></li></ol></li></ol></li><li>Title 5
<ol></ol></li></ol>

1. 标题 1\n
2. 标题 2\n
   1. 标题 3\n
   2. 标题 4\n
      1. 标题 6\n
3. 标题 5\n

检查后编辑为解决方案

为了避免空叶子：

function r( $a, $level) {
   $r = '' ;
   foreach ( $a as $i ) {
       if ($i['parent_id'] == $level ) {
          $r = $r . "<li>" . $i['title'] . r( $a, $i['id'] ) . "</li>";
       }
   }
   return ($r==''?'':"<ol>". $r . "</ol>");
}

Answer 2

您可以尝试以下方法

$array = array (
    "0" => array (
        "id" => 1,
        "title" => "Title 1",
        "parent_id" => NULL,
        "depth" => 0
    ),
    "1" => array (
        "id" => 2,
        "title" => "Title 2",
        "parent_id" => NULL,
        "depth" => 0
    ),
    "2" => array (
        "id" => 3,
        "title" => "Title 3",
        "parent_id" => 2,
        "depth" => 1
    ),
    "3" => array (
        "id" => 4,
        "title" => "Title 4",
        "parent_id" => 2,
        "depth" => 1
    ),
    "4" => array (
        "id" => 5,
        "title" => "Title 5",
        "parent_id" => NULL,
        "depth" => 0
    ),
    "5" => array (
        "id" => 6,
        "title" => "Title 6",
        "parent_id" => 4,
        "depth" => 0
    )
);

echo(make($array));

输出

<ol>
    <li>Title 1</li>
    <li>Title 2</li>
    <ol>
        <li>Title 3</li>
        <li>Title 4</li>
        <ol>
            <li>Title 6</li>
        </ol>
    </ol>
    <li>Title 5</li>
</ol>

使用的功能

function make(array $array, $no = 0) {
    $child = hasChildren($array, $no);
    if (empty($child))
        return "";
    $content = "<ol>\n";
    foreach ( $child as $value ) {
        $content .= sprintf("\t<li>%s</li>\n", $value['title']);
        $content .= make($array, $value['id']);
    }
    $content .= "</ol>\n";
    return $content;
}

function hasChildren($array, $id) {
    return array_filter($array, function ($var) use($id) {
        return $var['parent_id'] == $id;
    });
}

观看现场演示

Answer 3

以下数组：

Array
(
    [0] => Content
    [1] => Array
        (
            [0] => International
            [1] => Array
                (
                    [0] => Mexico
                    [1] => Array
                        (
                            [0] => Tamaulipas
                        )

                    [2] => USA
                )

        )

)

使用此功能：

function r($element) {
    foreach ($element as $value) {
        if (!is_array($value)) {
            echo "<li>";
            echo $value;
        } else {
            echo "<ul>";
            r($value);
            echo "</li>";
            echo "</ul>";
        }
    }
}

PHP代码：

echo "<ul>";
r($array);
echo "</ul>";

回报：

<ul>
    <li>Public</li>
    <li>User</li>
    <li>Content
        <ul>
            <li>International
                <ul>
                    <li>Mexico
                        <ul>
                            <li>Tamaulipas</li>
                        </ul>  
                    </li>
                    <li>USA</li>
                </ul>
            </li>
        </ul>
    </li>
</ul>