生成多级菜单

Question

I have a problem with the generated multi-level menu. I would like each menu level select another color (li class=menucolor). However, I managed to only the first and 2nd level do. I can't separate the second level from the third level. Please help.

SQL:

CREATE TABLE IF NOT EXISTS `menu` (
`id` int(11) NOT NULL auto_increment,
`id_parent` int(11) NOT NULL default '0',
`link` varchar(255) NOT NULL,
`order` int(11) NOT NULL default '0',
`title` varchar(255) collate utf8_polish_ci NOT NULL default '',
PRIMARY KEY  (`id`)
);


INSERT INTO `menu` (`id`, `id_parent`, `link`, `order`, `title`) VALUES
(1, 0, index.php, 3, 'Index'),
(3, 1, link1.php, 1, 'Art1'),
(4, 1, link2.php, 2, 'Art2'),
(5, 4, link2.php, 6, 'Other art'),
(6, 4, link2.php, 1, 'Art AAA'),
(7, 4, link2.php, 1, 'Art BBB'),
(8, 4, link2.php, 1, 'Art CCC'),

AND CODE:

<ul id="menu_left">
<?php
$menuArray = array();
$query = mysql_query('  select id, id_parent, link, order, title
                        from menu
                        order by order asc
              ');

while($row = mysql_fetch_array($query))
{
  $menuArray[] = array( 'id'           => $row['id'],
                        'id_parent'    => $row['id_parent'], 
                        'link'         => $row['link'],
                        'order'        => $row['order'], 
                        'title'        => $row['title']
              );
}

function menu($id)
{
  global $menuArray;
  $hasChildren = false;
  $resultArray = array();

  if (empty($menuArray))
  {
    return;
  }

  foreach ($menuArray as $value)
  {
    if ($value['id_parent'] == $id)
    {
      $resultArray[] = $value;

    }
  }

  foreach ($resultArray as $value)
  {
    if ($hasChildren === false)
    {
      $hasChildren = true;
      if ($value['id_parent'] == 0)
      {
      $j++
        ?>
        <!-- ul first -->
        <?php
      }
      else
      {
        ?>
       <!-- <ul> -->
        <?php
      }
    }
    if($j=='1') {
    echo '<li class="menucolor0">';
    }
    elseif($j!='1') {
    echo '<li class="menucolor1">';
    }
    ?>
    <a href=<?php echo $value['link']; ?>"><?php echo $value['title']; ?></a> 
    <?php
    menu($value['id']);
    ?> 
    </li>
    <?php
  }
  if ($hasChildren === true)
  {
  <!-- </ul> -->
  }
}

menu(0); 
?>    
        </ul>  

Answer 1

if($j=='1') {
echo '<li class="menucolor0">';
}
elseif($j!='1') {
echo '<li class="menucolor1">';
}

You're only allowing for two cases, either it equals 1 or it doesn't.

switch ($j) {
case 1:
    echo  '<li class="menucolor0">';
    break;
case 2:
     echo '<li class="menucolor1">';
    break;
case 3:
     echo '<li class="menucolor2">';
     break;
default:
     echo '<li class="menucolor0">;
     break;

}

Answer 2

Any direct solution to this would be very slow, I suggest you update your table as such:

<?php

$db = new PDO('mysql:dbname=databasename', 'username', 'password',
    array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"));

$db->prepare('ALTER TABLE `menu` ADD COLUMN `level` TINYINT NOT NULL DEFAULT 0;')->execute();

$db->prepare('UPDATE `menu` SET `level` = 1 WHERE `id_parent` = 0;')->execute();

$select = $db->prepare('SELECT `id` FROM `menu` WHERE `level` = :level');
$update = $db->prepare('UPDATE `menu` SET `level` = :level WHERE `id_parent` = :parent');

for( $i = 1; $i < 100; $i++ ) {
    $select->execute(array('level' => $i));
    while( ($current = $select->fetch(PDO::FETCH_COLUMN)) !== false )
        $update->execute(array('level' => $i + 1, 'parent' => $current));
}

and here is how you display the menu in the desired order:

<?php
// connect to database using PDO
$db = new PDO('mysql:dbname=databasename', 'username', 'password',
    array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"));


function createsubmenu( $item )
{
    global $db;
// prepare a query to get subitems of the current $item (those with parent = $item)
    $subsel = $db->prepare('SELECT id, link, title, level  FROM menu WHERE id_parent = :parent ORDER BY `order`');
// run the query
    $subsel->execute(array('parent' => $item));
    $text = '';
// fetch one row at a time, when no more rows are available $i
// will be false and while ends
    while( ($i = $subsel->fetch(PDO::FETCH_OBJ)) !== false ) {
// generate code for the current $item
// will recursively call createsubmenu to add possibly existing subitems
        $text .= '<li class="menucolor' . ($i->level - 1) . '">'
            .'<a href="' . htmlspecialchars($i->link) . '">' . htmlspecialchars($i->title) . '</a>'
            . createsubmenu($i->id) . '</li>';
    }
// there were no items for the current call
    if( $text == '' )
        return '';
// items were found, wrap them in an unordered list
    return '<ul>' . $text . '</ul>';
}

// call the function for toplevel items (the ones having parent 0)
echo createsubmenu(0);

don't forget to replace databasename, username and password in both scripts