Post entity with Respect/Relational

Post.php

<?php

namespace Hussani\Entity;

use Respect\Relational\Mapper;
use PDO;
use DateTime;

class Post extends AbstractEntity
{
    protected $title;
    protected $content;
    protected $date;
    protected $last_update;
    protected $status;
    protected $author;
    protected $categories = array();
    protected $tags = array();
    protected $mapper;

    public function __construct($id)
    {
        $this->mapper = new Mapper(new PDO('mysql:host=127.0.0.1;port=3306;dbname=blog','root',''));
        if (is_numeric($id)) {
            $this->load($id);
        }
    }

    public function load($id)
    {
        if (!is_numeric($id)) {
            return false;
        }
        $post = $this->mapper->post[$id]->user->fetch();

        if (!is_numeric($post->id)) {
            return false;
        }
        $this->id = $post->id;
        $this->title = $post->title;
        $this->content = $post->content;
        $this->date = new DateTime($post->date);
        $this->last_update = new DateTime($post->last_update);
        $this->status = $post->status;
        $this->author = $post->user_id;

    }

    /**
     * Getter for title
     *
     * @return string
     */
    public function getTitle()
    {
        return $this->title;
    }

    /**
     * Setter for title
     *
     * @param mixed $title Value to set
     * @return self
     */
    public function setTitle($title)
    {
        $this->title = $title;
        return $this;
    }

    /**
     * Getter for content
     *
     * @return mixed
     */
    public function getContent()
    {
        return $this->content;
    }

    /**
     * Setter for content
     *
     * @param mixed $content Value to set
     * @return self
     */
    public function setContent($content)
    {
        $this->content = $content;
        return $this;
    }

    /**
     * Getter for author
     *
     * @return mixed
     */
    public function getAuthor()
    {
        return $this->author;
    }

    /**
     * Setter for author
     *
     * @param mixed $author Value to set
     *
     * @return self
     */
    public function setAuthor($author)
    {
        $this->author = $author;
        return $this;
    }

    /**
     * Getter for categories
     *
     * @return array
     */
    public function getCategories()
    {
        if (!empty($this->categories)) {
            return $this->categories;
        }

        if (!is_numeric($this->id)) {
            return array();
        }

        return $this->mapper
                ->category->post_category->post[$this->id]->fetchAll();
    }

    /**
     * Getter for tags
     *
     * @return array
     */
    public function getTags()
    {
        if (!empty($this->tags)) {
            return $this->tags;
        }

        if (!is_numeric($this->id)) {
            return array();
        }

        return $this->mapper
                ->tag->post_tag->post[$this->id]->fetchAll();
    }

}