PHP/MySQL构建树形菜单

Question

我想在PHP和MySQL中从我的数据库中构建一个无序列表菜单树。

我有一个页面对象数组，我从数据库返回。每个页面对象都有parent_id属性，如果它没有父项，则设置为null。这里的页面对象是什么样子：

page object 
    id 
    title 
    parent_id 

如果可能的话，我想这样做递归仅命中一次数据库，因为我将要建立在几乎每个请求的菜单。我想创建一个函数，我可以传递我的数组对象，它将返回html列表。

Answer 1

我喜欢@马里奥的解决方案，并在预防多余的<ul>方面有所改进。我只想建议这样做对你的SQL查询的ORDER BY得到你想要的（订单甚至可能建议重量/顺序列在菜单中添加到架构

数据设置：

$menu = array(// Presumed to have been coming from a SQL SELECT, populated for demo. 
    array('id'=>1,'title'=>'Menu 1',   'parent_id'=>null), 
    array('id'=>2,'title'=>'Sub 1.1',   'parent_id'=>1), 
    array('id'=>3,'title'=>'Sub 1.2',   'parent_id'=>1), 
    array('id'=>4,'title'=>'Sub 1.3',   'parent_id'=>1), 
    array('id'=>5,'title'=>'Menu 2',   'parent_id'=>null), 
    array('id'=>6,'title'=>'Sub 2.1',   'parent_id'=>5), 
    array('id'=>7,'title'=>'Sub Sub 2.1.1', 'parent_id'=>6), 
    array('id'=>8,'title'=>'Sub 2.2',   'parent_id'=>5), 
    array('id'=>9,'title'=>'Menu 3',   'parent_id'=>null), 
); 

处理：

function has_children($rows,$id) { 
    foreach ($rows as $row) { 
    if ($row['parent_id'] == $id) 
     return true; 
    } 
    return false; 
} 
function build_menu($rows,$parent=0) 
{ 
    $result = "<ul>"; 
    foreach ($rows as $row) 
    { 
    if ($row['parent_id'] == $parent){ 
     $result.= "<li>{$row['title']}"; 
     if (has_children($rows,$row['id'])) 
     $result.= build_menu($rows,$row['id']); 
     $result.= "</li>"; 
    } 
    } 
    $result.= "</ul>"; 

    return $result; 
} 
echo build_menu($menu); 

输出：

<ul> 
 
    <li>Menu 1<ul> 
 
    <li>Sub 1.1</li> 
 
    <li>Sub 1.2</li> 
 
    <li>Sub 1.3</li> 
 
    </ul></li> 
 
    <li>Menu 2<ul> 
 
    <li>Sub 2.1<ul> 
 
     <li>Sub Sub 2.1.1</li> 
 
    </ul></li> 
 
    <li>Sub 2.2</li> 
 
    </ul></li> 
 
    <li>Menu 3</li> 
 
</ul>

Answer 2

而不是递归查询数据库，您可以拉出所有条目并使输出函数递归。这往往是微不足道的：

function print_list($array, $parent=0) { 
    print "<ul>"; 
    foreach ($array as $row) { 
     if ($row->parent_id == $parent) { 
      print "<li>$row->title"; 
      print_list($array, $row->id); # recurse 
      print "</li>"; 
    } } 
    print "</ul>"; 
} 

这只是筑巢重要<ul> s转换<li>。或者只是使用HTML，并关闭</li>。

其实这打印太多<ul> s，所以我会检查sublevels的存在，并避免直接打印它。

Answer 3

我结束了该溶液（pastebin reference）去：

<?php 

/** 
* Generate HTML for multi-dimensional menu from MySQL database 
* with ONE QUERY and WITHOUT RECURSION 
* @author J. Bruni 
*/ 
class MenuBuilder 
{ 
    /** 
    * MySQL connection 
    */ 
    var $conn; 

    /** 
    * Menu items 
    */ 
    var $items = array(); 

    /** 
    * HTML contents 
    */ 
    var $html = array(); 

    /** 
    * Create MySQL connection 
    */ 
    function MenuBuilder() 
    { 
     $this->conn = mysql_connect('localhost', 'user', 'pass'); 
     mysql_select_db('example', $this->conn); 
    } 

    /** 
    * Perform MySQL query and return all results 
    */ 
    function fetch_assoc_all($sql) 
    { 
     $result = mysql_query($sql, $this->conn); 

     if (!$result) 
      return false; 

     $assoc_all = array(); 

     while($fetch = mysql_fetch_assoc($result)) 
      $assoc_all[] = $fetch; 

     mysql_free_result($result); 

     return $assoc_all; 
    } 

    /** 
    * Get all menu items from database 
    */ 
    function get_menu_items() 
    { 
     // Change the field names and the table name in the query below to match tour needs 
     $sql = 'SELECT id, parent_id, title, link, position FROM menu_item ORDER BY parent_id, position;'; 
     return $this->fetch_assoc_all($sql); 
    } 

    /** 
    * Build the HTML for the menu 
    */ 
    function get_menu_html($root_id = 0) 
    { 
     $this->html = array(); 
     $this->items = $this->get_menu_items(); 

     foreach ($this->items as $item) 
      $children[$item['parent_id']][] = $item; 

     // loop will be false if the root has no children (i.e., an empty menu!) 
     $loop = !empty($children[$root_id]); 

     // initializing $parent as the root 
     $parent = $root_id; 
     $parent_stack = array(); 

     // HTML wrapper for the menu (open) 
     $this->html[] = '<ul>'; 

     while ($loop && (($option = each($children[$parent])) || ($parent > $root_id))) 
     { 
      if ($option === false) 
      { 
       $parent = array_pop($parent_stack); 

       // HTML for menu item containing childrens (close) 
       $this->html[] = str_repeat("\t", (count($parent_stack) + 1) * 2) . '</ul>'; 
       $this->html[] = str_repeat("\t", (count($parent_stack) + 1) * 2 - 1) . '</li>'; 
      } 
      elseif (!empty($children[$option['value']['id']])) 
      { 
       $tab = str_repeat("\t", (count($parent_stack) + 1) * 2 - 1); 

       // HTML for menu item containing childrens (open) 
       $this->html[] = sprintf(
        '%1$s<li><a href="%2$s">%3$s</a>', 
        $tab, // %1$s = tabulation 
        $option['value']['link'], // %2$s = link (URL) 
        $option['value']['title'] // %3$s = title 
       ); 
       $this->html[] = $tab . "\t" . '<ul class="submenu">'; 

       array_push($parent_stack, $option['value']['parent_id']); 
       $parent = $option['value']['id']; 
      } 
      else 
       // HTML for menu item with no children (aka "leaf") 
       $this->html[] = sprintf(
        '%1$s<li><a href="%2$s">%3$s</a></li>', 
        str_repeat("\t", (count($parent_stack) + 1) * 2 - 1), // %1$s = tabulation 
        $option['value']['link'], // %2$s = link (URL) 
        $option['value']['title'] // %3$s = title 
       ); 
     } 

     // HTML wrapper for the menu (close) 
     $this->html[] = '</ul>'; 

     return implode("\r\n", $this->html); 
    } 
} 

实施例的数据：

CREATE TABLE `menu_item` (
    `id` int(11) NOT NULL, 
    `title` varchar(75) DEFAULT NULL, 
    `link` varchar(100) DEFAULT NULL, 
    `parent_id` int(11) DEFAULT NULL, 
    `position` int(11) DEFAULT NULL, 
    PRIMARY KEY (`id`) 
); 

INSERT INTO `menu_item` (`id`, `title`, `link`, `parent_id`, `position`) VALUES (1,'1','1.html',0,1); 
INSERT INTO `menu_item` (`id`, `title`, `link`, `parent_id`, `position`) VALUES (2,'2','2.html',0,2); 
INSERT INTO `menu_item` (`id`, `title`, `link`, `parent_id`, `position`) VALUES (3,'11','11.html',1,1); 
INSERT INTO `menu_item` (`id`, `title`, `link`, `parent_id`, `position`) VALUES (4,'12','12.html',1,2); 
INSERT INTO `menu_item` (`id`, `title`, `link`, `parent_id`, `position`) VALUES (5,'21','21.html',2,1); 
INSERT INTO `menu_item` (`id`, `title`, `link`, `parent_id`, `position`) VALUES (6,'22','22.html',2,2); 
INSERT INTO `menu_item` (`id`, `title`, `link`, `parent_id`, `position`) VALUES (7,'3','3.html',0,3); 

用法：

$menu = new MenuBuilder(); 
echo '<pre>' . htmlentities($menu->get_menu_html()) . '</pŕe>';