在PHP中递归创建一个多维数组

Question

我试图找出编写PHP函数的最佳方法,该函数将从mysql表中递归地构建具有未知数量的子级别的多维数组.其目的是创建一个数据结构,该数据结构可以循环以在网站上创建导航菜单,每个菜单项可能具有带子菜单项的子菜单.

表中的注释字段是:
int ItemID
int ParentID
varchar ItemText
text ItemLink
tinyint HasChildren

所以函数返回数组的一个例子是:

$menuItems = 
    array(
        itemID# => 
            array(
                'ItemText' => 'Home',
                'ItemLink' => 'index.php',
                'Children' => array(
                        itemID# => array (
                            'ItemText' => 'Home Sub 1',
                            'ItemLink' => 'somepage.php',
                            'Children' => 0
                        ),
                        itemID# => array (
                            'ItemText' => 'Home Sub 2',
                            'ItemLink' => 'somepage2.php',
                            'Children' => 0
                        ),
                    )
            ),
        itemID# => 
            array(
                'ItemText' => 'Contact',
                'ItemLink' => 'contact.php',
                'Children' => 0
            )
        )
    );

如果有人能指出我正确的方向来实现这一点,我将非常感激.谢谢!

Answer 1

不是太难.您所做的是将菜单项存储在一个数组中,您可以通过ID查找它们.然后迭代菜单项,如果它们具有非null的ParentID,则将它们添加到父项的子项列表中.然后从主列表中删除所有子项,这样您只剩下顶级项目.

码:

<?php
$menuItems = array
(
    1 => array
    (
        'ItemText' => 'Home',
        'ItemLink' => 'index.php',
        'ParentID' => null,
    ),

    2 => array
    (
        'ItemText' => 'Home Sub 1',
        'ItemLink' => 'somepage.php',
        'ParentID' => 1,
    ),

    3 => array
    (
        'ItemText' => 'Home Sub 2',
        'ItemLink' => 'somepage2.php',
        'ParentID' => 1,
    ),

    4 => array
    (
        'ItemText' => 'Contact',
        'ItemLink' => 'contact.php',
        'ParentID' => null,
    ),
);

// Each node starts with 0 children
foreach ($menuItems as &$menuItem)
    $menuItem['Children'] = array();

// If menu item has ParentID, add it to parent's Children array    
foreach ($menuItems as $ID => &$menuItem)
{
    if ($menuItem['ParentID'] != null)
        $menuItems[$menuItem['ParentID']]['Children'][$ID] = &$menuItem;
}

// Remove children from $menuItems so only top level items remain
foreach (array_keys($menuItems) as $ID)
{
    if ($menuItems[$ID]['ParentID'] != null)
        unset($menuItems[$ID]);
}

print_r($menuItems);
?>

输出:

Array
(
    [1] => Array
        (
            [ItemText] => Home
            [ItemLink] => index.php
            [ParentID] => 
            [Children] => Array
                (
                    [2] => Array
                        (
                            [ItemText] => Home Sub 1
                            [ItemLink] => somepage.php
                            [ParentID] => 1
                            [Children] => Array
                                (
                                )

                        )

                    [3] => Array
                        (
                            [ItemText] => Home Sub 2
                            [ItemLink] => somepage2.php
                            [ParentID] => 1
                            [Children] => Array
                                (
                                )

                        )

                )

        )

    [4] => Array
        (
            [ItemText] => Contact
            [ItemLink] => contact.php
            [ParentID] => 
            [Children] => Array
                (
                )

        )

)