PHP递归引导下拉菜单

我使用这段代码为infinte菜单创建一个引导下拉列表

<ul class="nav">

                            <?php 
              $menu_items = array(
                (object) array('id'=>'1', 'name'=>'Electronics', 'parent_menu_id'=>'0'),
                (object) array('id'=>'2', 'name'=>'Books', 'parent_menu_id'=>'0'),
                (object) array('id'=>'3', 'name'=>'Toys', 'parent_menu_id'=>'0'),
                (object) array('id'=>'4', 'name'=>'Kitchen', 'parent_menu_id'=>'0'),
                (object) array('id'=>'5', 'name'=>'Apparel', 'parent_menu_id'=>'0'),
                (object) array('id'=>'6', 'name'=>'Shirts', 'parent_menu_id'=>'5'),
                (object) array('id'=>'7', 'name'=>'Pants', 'parent_menu_id'=>'5'),
                (object) array('id'=>'8', 'name'=>'Hats', 'parent_menu_id'=>'5'),
                (object) array('id'=>'9', 'name'=>'Gloves', 'parent_menu_id'=>'5'),
                (object) array('id'=>'10', 'name'=>'Ballcaps', 'parent_menu_id'=>'8'),
                (object) array('id'=>'11', 'name'=>'Beanies', 'parent_menu_id'=>'8'),
                (object) array('id'=>'12', 'name'=>'Wool', 'parent_menu_id'=>'11'),
                (object) array('id'=>'13', 'name'=>'Polyester', 'parent_menu_id'=>'11'),
                (object) array('id'=>'14', 'name'=>'Jimsider.com', 'parent_menu_id'=>'4'),
              );

                global $menuItems;
                global $parentMenuIds;
                //create an array of parent_menu_ids to search through and find out if the current items have an children
                foreach($menu_items as $parentId)
                {
                  $parentMenuIds[] = $parentId->parent_menu_id;
                }
                //assign the menu items to the global array to use in the function
                $menuItems = $menu_items;

                //recursive function that prints categories as a nested html unorderd list
                function generate_menu($parent)
                {
                        $has_childs = false;

                        //this prevents printing 'ul' if we don't have subcategories for this category
                        global $menuItems;
                        global $parentMenuIds;
                        //use global array variable instead of a local variable to lower stack memory requierment
                        foreach($menuItems as $key => $value)
                        {
                            if ($value->parent_menu_id == $parent) 
                            {    
                                //if this is the first child print '<ul>'
                                if ($has_childs === false)
                                {
                                  //don't print '<ul>' multiple times  
                                  $has_childs = true;
                                  if($parent != 0)
                                  {
                                    echo '<ul class="dropdown-menu">';
                                  }
                                }

                                if($value->parent_menu_id == 0 && in_array($value->id, $parentMenuIds))
                                {
                                  echo '<li class="dropdown"><a class="dropdown-toggle" data-toggle="dropdown" href="#">' . $value->name . '<b class="caret"></b></a>';
                                }
                                else if($value->parent_menu_id != 0 && in_array($value->id, $parentMenuIds))
                                {
                                  echo '<li class="dropdown-submenu"><a href="#">' . $value->name . '</a>';
                                }
                                else
                                {
                                  echo '<li><a href="#">' . $value->name . '</a>';
                                }
                                generate_menu($value->id);

                                //call function again to generate nested list for subcategories belonging to this category
                                echo '</li>';
                            }
                        }
                        if ($has_childs === true) echo '</ul>';
                }
                generate_menu(0);
              ?>
    <!-- End Dynamic Nav -->
         </li>
            </ul>

但结果是

<ul class="nav">
 <li><a href="#">Electronics</a></li>
 <li><a href="#">Books</a></li>
 <li><a href="#">Toys</a></li>
 <li class="dropdown"><a class="dropdown-toggle" data-toggle="dropdown" href="#">Kitchen<b class="caret"></b></a>
    <ul class="dropdown-menu">
        <li><a href="#">Jimsider.com</a></li>
    </ul>
 </li>
 ....... 
</ul> 

....... 

父菜单id=0的所有菜单项都列为菜单，而我需要在一个菜单“类别”下列出所有内容。

函数toULlistproduct（$arr）
 function toULlistproduct($arr)
 {
     $html = '<ul>'.PHP_EOL;
     foreach ($arr as $k => $v)
     {          
          if(is_array($v)){          
              $html .= '<li><a href="#" id="' . $k . '"  >'.$k.'</a></li>' ;
              $html .= toULlistproduct($v);
          }else{
              $html .= '<li><a href="#" id="' . $k . '"  >'.$v.'</a></li>' ;
          }
     }
     $html .= '</ul>'.PHP_EOL;
    return $html;
 }
$arr = array(
    'a' => array(1,2,3,4,5,6,7,8,9,...),
);
echo toULlistproduct($arr);

{
$html='
'.PHP\u EOL；
foreach（$arr为$k=>$v）
{          
如果（是_数组（$v））{
$html.='
'；
$html.=toULlistproduct（$v）；
}否则{
$html.='
'；
}
}
$html.='
'.PHP\u EOL；
返回$html；
}
$arr=数组(
'a'=>数组（1,2,3,4,5,6,7,8,9，…），
);
echo toULlistproduct（$arr）；