Php 从多维数组创建嵌套列表

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
    )
)

<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>

我要做的是迭代这个数组并从中创建一个嵌套列表。所以结果应该是这样的：

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
    )
)

<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>

我一直在想一个办法，怎样才能完成这件事。但到目前为止，每一次尝试都失败了

有人知道如何从这样的数组中创建这样的嵌套列表吗

请注意，我对给定的数据没有任何控制权。我只需调用一个API，它就会返回json数据，并将其转换为数组。数组看起来与我描述的完全一样。

您应该使用递归：

首先使用“php”语法创建数组：

<?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
    )
);

代码如下：

结果是：

标题1\n标题2\n标题3\n标题4\n标题6\n标题5\n 检查后编辑为解决方案

要避免空树叶：

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>");
}

---

你可以试试下面的方法

$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;
    });
}

以下阵列：

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>";

返回：

<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>

---

从表面上看，这看起来很简单，但我认为你仍然缺乏信息，无法为你的情况找到最佳答案。首先，您是如何获得阵列的？它来自数据库吗？是否有可能以不同的方式存储，或者您是否被困在这种方式中？深度是否保证现在或将来不会超过1或2，或者您是否计划进行不确定数量的子级别？增加或删除类别的频率如何？我建议您检查一下，因为嵌套模型可能更符合您的需要。非常好的答案，谢谢。你能告诉我，假设数组元素没有深度键，我们如何设置最大深度吗。。我们需要一个$level=0；我想$max_level=3。但是如何在你的功能中放置它们呢？@Baba，他是一个很好的位置。希望你能抽出时间来复习一下。