如何使用 Laravel 创建数据库驱动的多级导航菜单

<?php

class Navigation extends Eloquent {

    /**
     * The database table used by the model.
     *
     * @var string
     */
    protected $table = 'navigation';

    /**
     * Get the unique identifier for the menu item.
     *
     * @return mixed
     */
    public function getItemIdentifier()
    {
        return $this->getKey();
    }

}

<?php

class Navigation extends Eloquent {

    /**
     * The database table used by the model.
     *
     * @var string
     */
    protected $table = 'navigation';

    public function parent() {

        return $this->hasOne('navigation', 'id', 'parent_id');

    }

    public function children() {

        return $this->hasMany('navigation', 'parent_id', 'id');

    }  

    public static function tree() {

        return static::with(implode('.', array_fill(0, 4, 'children')))->where('parent_id', '=', NULL)->get();

    }

}

<?php

class HomeController extends BaseController {

    protected $layout = "layouts.main";

    public function showWelcome()
    {

        $items = Navigation::tree();

        $this->layout->content = View::make('layouts.home.index')->withItems($items);

    }

}

<ul>
    @foreach($items as $item)
        <li>{{ $item->title }}
            @foreach($item['children'] as $child)
            <li>{{ $child->title }}</li>
            @endforeach
        </li>
    @endforeach
</ul>