PHP的多级菜单

Question

我有一个这样的主题表：

id
title
parent_id
full_path

full_path 用于查找父项为递归。像这样：

+----+-----------+-----------+-----------+
| id | title     | full_path | parent_id |
+----+-----------+-----------+-----------+
| 40 | home      | 40        |         0 |
| 41 | myhome1   | 41        |         0 |
| 42 | ****      | 40-42     |        40 |
| 43 | *****     | 41-43     |        41 |
| 44 | ***       | 44        |         0 |
| 45 | ****      | 45        |         0 |
| 46 | *****     | 46        |         0 |
| 49 | ******    | 49        |         0 |
| 50 | **** **   | 40-42-50  |        42 |
| 51 | **** **   | 40-42-51  |        42 |
| 52 | **** **   | 40-42-52  |        42 |
| 53 | *******   | 40-53     |        40 |
| 54 | ****      | 40-54     |        40 |
| 55 | ***       | 41-55     |        41 |
| 56 | **** **** | 40-42-56  |        42 |
| 57 | *******   | 44-57     |        44 |
+----+-----------+-----------+-----------+

我如何得到这样的递归数组：

array
(
    40 => array
    (
        42 => array
        (
            50,51,52,etc.
        ),
        53,
        54
    )
    41 => array
    (
        43,
        55,
    ),
    44 => array
    (
        57,
    ),
    etc...
)

我可以使用full_path创建多级菜单吗？

Answer 1

您可以使用以下代码执行此操作。请记住，这是有效的，因为您的主题数组将非常小，并且发生的递归将是最小的。不要在大型​​阵列上使用这种方法。

<?php
$query = "SELECT id, parent_id FROM subjects";
//execute with your prefered method, eg mysqli

$rows = array();
while($row = $result->fetch_array(MYSQLI_ASSOC))
{
  $rows[] = $row;
}

function getChildren($p) {
  global $rows;
  $r = array();
  foreach($rows as $row) {
    if ($row['parent_id']==$p) {
      $r[$row['id']] = getChildren($row['id']);
    }
  }
  return $r;
}

$final = getChildren(0);
?>

Answer 2

我编辑了Hugo的代码：

MySQL的代码：sqlfiddle

我们这样的表：

ID | Categories_name | Parent_id

我们的数据是（图片上的数字，显示ID类别）：

我们的PHP代码：

<?php
    $db=mysql_connect("127.0.0.1","root","");
    $db_name = "test";
    mysql_select_db($db_name,$db);


    $query = "SELECT `id`,`cat_name`,`parent_id` FROM `categories`";
    $result=mysql_query($query);
    $num=mysql_num_rows($result);

    $level_each_rows = array();
    $rows = array();
    for($i = 0 ; $i < $num ; $i++)
    {
        $q_data = mysql_fetch_array($result);
        $rows[] = $q_data;
    }

    function getChildren_string($p)
    {
        global $rows;
        global $level_each_rows;
        $r = array();
        $i = 0;
        $return = '';
        foreach($rows as $row)
        {
            if ($row['parent_id'] == $p)
            {
                if($row['parent_id'] == 0)
                {
                    $level_each_rows[$row['id']]['i'] = 0;
                }
                else
                {
                    $level_each_rows[$row['id']]['i'] = $level_each_rows[$row['parent_id']]['i'] + 1;
                }
                $return = $return.'
                <tr>
                    <td>'.$row['parent_id'].'</td>
                    <td><div style="margin:0px '.($level_each_rows[$row['id']]['i'] * 35).'px;">['.$row['id'].'] - '.$row['cat_name'].'</div></td>
                </tr>

                ';
                $return = $return.getChildren_string($row['id']);
                $i++;
            }
        }
        //---
        return $return;
    }

    $childs = getChildren_string(0);

    echo '
    <div dir="ltr">
        <table dir="ltr" border="1">
            <tr>
                <td>Parent ID</td>
                <td>Child ID</td>
            </tr>
    ';
    echo $childs;
    echo '
        </table>
    </div>
    ';
?>

<强>结果：