How to Build Unlimited Levels of Menus with PHP and MySQL: A Step-by-Step Guide?

Building Unlimited Levels of Menus with PHP and MySQL

In website development, menu navigation plays a crucial role in user experience. However, building menus that support unlimited levels of submenus can be challenging. Let's delve into a comprehensive approach to achieve this functionality using PHP and MySQL.

Database Structure and Menu System

The database structure you mentioned is a common approach to represent a hierarchical menu system. Each menu item has a parent field to establish the parent-child relationship. Parent ID 0 indicates top-level menu items.

Retrieving Top-Level Menus

Your existing PHP code for retrieving top-level menus is correct:

<code class="php">$list = $obj->childmenu($parentid);
foreach($list as $menu) {
    echo '<li><a href="#">'.$name.'</a></li>';
}</code>

Identifying Submenu Existence and Display

Your query aims to identify if a menu item has child menus and display them within its list item. To achieve this, you need to modify your SQL query and PHP code.

Optimized SQL Query

Using a single SQL query, we can retrieve all menu items ordered by their parent ID and position:

<code class="sql">SELECT id, parent_id, title, link, position FROM menu_item ORDER BY parent_id, position;</code>

Refined PHP Code

The revised PHP code incorporates a stack to track the current menu level and ensures efficient handling of nested menus:

<code class="php">$items = $query_results;  // Assuming $query_results contains the result of the SQL query

$html = '';
$parent = 0;
$parent_stack = array();

foreach ( $items as $item ) {
    if ( !empty($item['parent_id']) ) {
        $children[$item['parent_id']][] = $item;
    }
}

while ( ( $option = each( $children[$parent] ) ) || ( $parent > 0 ) ) {
    if ( !empty( $option ) ) {
        if ( !empty( $children[$option['value']['id']] ) ) {
            $html .= '<li>' . $option['value']['title'] . '<ul>';
            array_push( $parent_stack, $parent );
            $parent = $option['value']['id'];
        } else {
            $html .= '<li>' . $option['value']['title'] . '</li>';
        }
    } else {
        $html .= '</ul>';
        $parent = array_pop( $parent_stack );
    }
}

echo $html;</code>

This updated code will effectively process the menu structure, create HTML markup for nested menus, and display them within their respective list items.

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