The Article Class

<?php
/**
 * This class handle the article objects of the cms
 */

class Article{
    public $id = null; //@var int: article ID
    public $pubDate = null; //@var int: date of publication, store as Unix Timestamp
    public $title = null; //@var string: title of article
    public $summary = null; //@var string: summary of the article
    public $content = null; //@var string: html content of article

    /*
     * Constructor
     */
    public function __construct( $data=array() ) {
        if( isset( $data['id']) )
            $this->id = (int)$data['id'];
        if( isset( $data['pubDate']) )
            $this->pubDate = (int)$data['pubDate'];
        if ( isset( $data['title'] ) )
            // filter out characters, for security purpose
            $this->title = preg_replace ( "/[^\.\,\-\_\'\"\@\?\!\:\$ a-zA-Z0-9()]/", "", $data['title'] );
        if ( isset( $data['summary'] ) )
            // filter out characters, for security purpose
            $this->title = preg_replace ( "/[^\.\,\-\_\'\"\@\?\!\:\$ a-zA-Z0-9()]/", "", $data['summary'] );
        if ( isset ($data['content']) )
            $this->content = $data['content'];
    }

    /*
     * Store values from a form into the object's properties
     * @formData the POST data from the form
     */
    public function storeFormValues($formData=array()) {
        // stores all the parameters
        $this->__construct($formData);

        // stores the publication data in appropriate form
        if (isset($formData['pubDate'])) {
            // split the string, because pubdate is in form YYYY-M-D
            $pubDate = explode('-', $formValue['pubDate']);
            if (count($pubDate) == 3)
                list($y, $m, $d) = $pubDate;
            // convert to unix timestamp
            $this->pubDate = mkTime(0, 0, 0, $m, $d, $y);
        }
    }

    /*
     * Get article object by id
     * This function is static due to the need of returning an article without
     * having to have an existing article object
     * @param $id int the id of the article
     */
    public static function getArticleById($id) {
        // create a new PDO object
        $conn = new PDO(DB_DSN, DB_USERNAME, DB_PASSWORD);
        // sql command
        // :id is a place holder for article id (security purpose)
        $sql = "SELECT *, UNIX_TIMESTAMP(pubDate) AS pubDate FROM artciles WHERE id = :id";
        // prepare a PDO statement
        $st = $conn->prepare($sql);
        // bind the id value to the statement
        $st->bindValue(":id", $id, PDO::PARAM_INT);
        // execute the sql command
        $st->execute();
        // retrieve the row data
        $row = $st->fetch();
        // if data found then return data
        if ($row)
            return new Article($row);
        // close the connection
        $conn = null;
    }

    /*
     * Get all articles in the db
     * @return: array contains article objects
     */
    public static function getAllArticles() {
        // create a new PDO object
        $conn = new PDO(DB_DSN, DB_USERNAME, DB_PASSWORD);
        // sql command
        $sql = "SELECT *, UNIX_TIMESTAMP(pubDate) as pubDate FROM articles";
        $articleList = array();
        foreach ($conn->query($sql) as $row)
            // create a new article and add it to the list
            $article = new Article($row);
            $articleList[] = $article;
    }

    /*
     * Inserts the current article object into the database
     * If the article object already has an id, don't insert it into the db
     * since db already has it!
     */
    public function insert() {
        // if the article already has an id, don't insert!
        if (!is_null($this->id)) trigger_error("Article::insert(): Cannot insert an article that already has an id", E_USER_ERROR);

        // create a new PDO object
        $conn = new PDO(DB_DSN, DB_USERNAME, DB_PASSWORD);
        // sql statement with placeholders
        $sql = "INSERT INTO articles (pubDate, title, summary, content) VALUES ( FROM_UNIXTIME(:pubDate), :title, :summary, :content)";
        // prepare pdo statement
        $st = $conn->prepare($sql);
        // bind necessary values
        $st->bindValue(":pubDate", $this->pubDate, PDO::PARAM_STR);
        $st->bindValue(":title", $this->title, PDO::PARAM_STR);
        $st->bindValue(":summary", $this->summary, PDO::PARAM_STR);
        $st->bindValue(":content", $this->content, PDO::PARAM_STR);
        // excute
        $st->execute();
        // get id
        $this->id = $conn->lastInsertId();
        // close the connection
        $conn = null;
    }

    /*
     * Update an article record in the database
     */
    public function update() {
        // if the article doesn't have an id, trigger error
        if (is_null($this->id)) trigger_error("Article::update(): Cannot update article without an id", E_USER_ERROR);

        // create a new PDO object
        $conn = new PDO(DB_DSN, DB_USERNAME, DB_PASSWORD);
        // sql query with placeholders
        $sql = "UPDATE articles SET pubDate = FROM_UNIXTIME(:pubDate) title=:title, summary=:summary, content=:content WHERE id=:id";
        // prepare pdo statement
        $st = $conn->prepare($sql);
        // bind necessary values
        $st->bindValue(":pubDate", $this->pubDate, PDO::PARAM_STR);
        $st->bindValue(":title", $this->title, PDO::PARAM_STR);
        $st->bindValue(":summary", $this->summary, PDO::PARAM_STR);
        $st->bindValue(":content", $this->content, PDO::PARAM_STR);
        $st->bindValue(":id", $this->id, PDO::PARAM_INT);
        // excute
        $st->execute();
        // close the connection
        $conn = null;
    }

    /*
     * Delete the current article object from the db
     */
    public function delete(){
        // if the article doesn't have an id, trigger error
        if (is_null($this->id)) trigger_error("Article::delete(): Cannot delete article without an id", E_USER_ERROR);

        // create a new PDO object
        $conn = new PDO(DB_DSN, DB_USERNAME, DB_PASSWORD);
        // sql query, LIMIT 1 is for safety reason to make sure only 1 article is deleted at a time
        $sql = "DELETE FROM articles WHERE id=:id LIMIT 1";
        $st = $conn->prepare($sql);
        $st->bindValue(":id", $this->$id, PDO::PARAM_INT);
        $st->execute();
        $conn = null;
    }
}
?>