Creating a PHP class to create Wordpress custom post types with dynamic metaboxes

Content_Type_Jobs_Template.php

<?php namespace content;
/**
 * See blog post for details: http://www.suburban-glory.com/blog?page=174
 * 
 * Content_Type
 * 
 * @package class for creating dynamic Wordpress metaboxes
 * @author Andy Walpole
 * @copyright AWalpole
 * @version 2013
 * @access public
 * @license the same as Wordpress
 */

class Content_Type_Jobs_Template {

    static $wpdb = null;

    /**
     * Content_Type::__construct()
     * 
     * @return
     */
    public function __construct() {

        global $wpdb;
        self::$wpdb = $wpdb;

        add_action('init', array(&$this, 'content_type'));

        // I have a habit of using sessions but forgetting to use session_start()
        // So I place this in the __construct method and use session_regenerate_id() for security
        if (session_id() == '') {
            session_start();
            session_regenerate_id(true);
        }

    }

    /**
     * Content_Type_Jobs_Template::metabox_attributes()
     * 
     * This is the meat and bones of the meta box array and is used repeatedly in the code underneath
     * 
     * Called in Content_Type::text_one_html() AND 
     * 
     * @return array
     */

    public function metabox_attributes() {

        return array(

            'title' => array(
                'name' => 'title',
                'type' => 'text',
                'title' => 'Title',
                'description' => 'The job title',
                ),

            'description' => array(
                'name' => 'description',
                'type' => 'text',
                'title' => 'Description',
                'description' => 'Short description',
                ),

            'location' => array(
                'name' => 'location',
                'type' => 'text',
                'title' => 'Location',
                'description' => 'Location of job',
                ),

            'date' => array(
                'name' => 'date',
                'type' => 'text',
                'title' => 'Date',
                'description' => 'Date posted',
                ),

            );

    } // end function metabox_attributes()

    /**
     * Content_Type_Jobs_Template::content_type()
     * 
     * This is the to register the content type
     * 
     * 
     */
    public function content_type() {

        $labels = array(
            'name' => _x('Jobs Layout', 'post type general name'),
            'singular_name' => _x('Jobs Layout', 'post type singular name'),
            'add_new' => _x('Add New', 'book'),
            'add_new_item' => __('Jobs Layout'),
            'edit_item' => __('Edit Jobs Layout type'),
            'new_item' => __('New Jobs Layout type'),
            'all_items' => __('All Jobs Layout types'),
            'view_item' => __('View Jobs Layout types'),
            'search_items' => __('Search Jobs Layout types'),
            'not_found' => __('No Jobs Layout types found'),
            'not_found_in_trash' => __('No Jobs Layout types found in Trash'),
            'parent_item_colon' => '',
            'menu_name' => __('Jobs Layout'),
            );

        $args = array(
            'labels' => $labels,
            'description' => 'Jobs',
            'public' => true,
            'publicly_queryable' => true,
            'show_ui' => true,
            'show_in_menu' => true,
            'query_var' => true,
            'rewrite' => true,
            'capability_type' => 'post',
            'has_archive' => true,
            'hierarchical' => false,
            'menu_position' => null,
            'register_meta_box_cb' => array(&$this, 'add_metaboxes'),
            'taxonomies' => array('category'),
            'supports' => array(
                'title',
                'editor',
                'author',
                'thumbnail',
                'excerpt',
                ));

        add_action('save_post', array(&$this, 'save_postdata'), 10, 2);
        add_action('admin_notices', array(&$this, 'my_post_admin_notices'), 10, 1);
        register_post_type('jobs', $args);

    }

    /**
     * Content_Type_Jobs_Template::add_metaboxes()
     * 
     * Calls the add_meta_box hook
     * Called in Content_Type_Jobs_Template::content_type()
     * 
     */
    public function add_metaboxes() {

        add_meta_box('jobs_metabox', 'Add individual jobs below', array(&$this, 'text_one_html'),
            'jobs', 'normal', 'high');

    }

    /**
     * Content_Type_Jobs_Template::text_one_html()
     * 
     * This is the html of the meta_boxes
     * Called in Content_Type_Jobs_Template::content_type()
     * 
     * @return string
     */
    public function text_one_html() {

        $new_meta_boxes = $this->metabox_attributes();

        global $post;

        if (!is_null($post)) {

            // creates the initial empty form fields to be populated by the user

            $form = '<table id="list-table">';
            $form .= '<tbody id="the-list" width="100%">';

            foreach ($new_meta_boxes as $key => $result) {

                if ($result['name'] == 'title') {

                    $form .= '<thead>';
                    $form .= '<tr>';
                    $form .= '<th class="left"><h4>Add a new job below</h4></th>';
                    $form .= '<th><h4>Values</h4></th>';
                    $form .= '</tr>';
                    $form .= '</thead>';

                }

                if ($result['type'] == 'text') {

                    $form .= '<tr>';
                    $form .= '<td class="left" width="30%">';
                    $form .= '<label for="'.$result['name'].'"><strong>'.$result['title'].
                        '</strong></label>';
                    $form .= '<div>'.$result['description'].'</div>';
                    $form .= '</td>';
                    $form .= '<td width="70%">';
                    $form .= '<input type="text" name="'.$result['name'].'" value="';
                    $form .= isset($_SESSION[$result['name']]) ? $_SESSION[$result['name']] : null;
                    $form .= '" class="regular-text"/>';
                    $form .= '</td>';
                    $form .= '</tr>';

                }

            } // end foreach

            $form .= '</tbody>';
            $form .= '</table>';

            echo $form;

            $meta = get_post_meta($post->ID);

            $y = $x = 0;

            // takes the multidimensional array from the database field and creates forms
            // populated by the data

            if (!empty($meta)) {

                // remove the _edit_last and _edit_lock arrays from the returned multidimensional array
                $remove = array('_edit_last', '_edit_lock');
                $meta = array_diff_key($meta, array_flip($remove));

                $form = '<table id="list-table">';
                $form .= '<tbody id="the-list" width="100%">';

                foreach ($meta as $key => $value) {

                    // remove all digits from the key. New form unique form attributes are created below
                    $key = preg_replace('/\d/', '', $key);

                    // make sure that all returned keys fit the original keys in the metabox_attributes method
                    if (!in_array($key, array_keys($this->metabox_attributes()))) continue;

                    // for every number of total keys in the metabox_attributes add an extra digit
                    // this is to ensure that all name attributes are unique
                    if ($x++ % count($this->metabox_attributes()) == 0) {

                        $y += 1;

                    }

                    // remove digit from the string
                    // and then use array_intersect_key() and array_flip() to find the array of
                    // the relevant corresponding key from the meta_attributes() method
                    // this is then used in the html

                    $key_array = array_intersect_key($this->metabox_attributes(), array_flip(array($key)));

                    if ($key_array[$key]['name'] == 'title') {

                        $form .= '<thead>';
                        $form .= '<tr>';
                        $form .= '<th class="left"><h4>'.implode('', $value).'</h4></th>';
                        $form .= '<th>&nbsp;</th>';
                        $form .= '</tr>';
                        $form .= '</thead>';

                    }

                    if ($key_array[$key]['type'] == 'text') {

                        $form .= '<tr>';
                        $form .= '<td class="left" width="30%">';
                        $form .= '<label for="'.$key.$y.'"><strong>'.$key_array[$key]['title'].
                            '</strong></label>';
                        $form .= '<div>'.$key_array[$key]['description'].'</div>';
                        $form .= '</td>';
                        $form .= '<td width="70%">';
                        $form .= '<input type="text" name="'.$key.$y.'" value="';
                        $form .= isset($_SESSION[$key.$y]) ? $_SESSION[$key.$y] : implode('', $value);
                        $form .= '" class="regular-text"/>';
                        $form .= '</td>';
                        $form .= '</tr>';

                    }

                }

                $form .= '</tbody>';
                $form .= '</table>';

                echo $form;

            }

        } // end if if (!is_null($post)) {

    } // end private function text_one_html() {

    /**
     * Content_Type_Jobs_Template::validation()
     * 
     * This is where all validation of form data takes place
     * This checks for equal values but it would be easy to add other types 
     * of validation as the errors are built into an array
     * 
     * @param array
     * @return array
     */

    protected function validation($form) {

        $error = array();

        // filter out unwanted parts of the $_POST
        foreach ($form as $key => $value) {
            if (!in_array(preg_replace('/\d/', '', $key), array_keys($this->metabox_attributes()))) {
                unset($form[$key]);
            } else {
                // this session data is used if there is a form error to repopulate the form fields
                // if the form has no error then the session data is destroyed
                $_SESSION[$key] = $value;
            }
        }

        // make sure that the the values are in proportion to that specified in the number
        // of fields in the metabox_attributes. For instance if there are 4 fields in the method, then there must
        // be no blank values in multiplications of 4, ie 4, 8 12
        if (count(array_values(array_filter($form, 'strlen'))) % count($this->metabox_attributes()) ==
            0) {

            return true;

        } else {

            $error[] = 'Please make sure that all '.count($this->metabox_attributes()).
                ' fields are filled in or leave all form fields empty for the job listing to be deleted';

            return $error;

        }

    }

    /**
     * Content_Type_Jobs_Template::save_postdata()
     * 
     * Calls the validation() method
     * If okay saves data
     * 
     * If not okay it then proceeds to the next stage which is 
     * 1. To switch the form to pending rather than published 
     * 2. Call the add_filter hook and place error message into a session
     */
    public function save_postdata() {

        global $post;

        if (!is_null($post)) {

            // don't do on autosave or when new posts are first created
            if ((defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) || $post->post_status == 'auto-draft') 
                    return $post->ID;

            // abort if not my custom type
            if ($post->post_type != 'jobs') return $post->ID;

            // sanitization here
            $form = array_map('stripslashes_deep', $_POST);

            $error = $this->validation($form);

            // if there are no errors then save or delete data
            if ($error === true) {

                // destory session here and save meta data
                foreach ($form as $key => $value) {
                    
                    // filter out unwanted parts of the $_POST
                     if (!in_array(preg_replace('/\d/', '', $key), array_keys($this->
                        metabox_attributes()))) continue;

                    if ($value != '') {

                        update_post_meta($post->ID, $key, strip_tags($value), false);

                    } else {

                        delete_post_meta($post->ID, $key, false);

                    }

                    // destroy session

                    $_SESSION = array();
                    
                } // end foreach

            } else {

                // on attempting to publish - check for completion and intervene if necessary
                if ((isset($_POST['publish']) || isset($_POST['save'])) && $_POST['post_status'] ==
                    'publish') {

                    self::$wpdb->update(self::$wpdb->posts, array('post_status' => 'pending'), array
                        ('ID' => $post->ID));

                } // end fi

                add_filter('wp_insert_post_data', array(&$this, 'add_redirect_filter'), 102);

                $this->add_redirect_filter();

                $_SESSION['error'] = serialize($error);


            } // end if($return == true) {

        } // end if(!null($post)) {

    } // public function ah_save_postdata() {


    /**
     * Content_Type::add_redirect_filter()
     * 
     */
    public function add_redirect_filter() {

        add_filter('redirect_post_location', array(&$this, 'my_redirect_post_location_filter'), 102);

    } // end public function add_redirect_filter() {

    /**
     * Content_Type::my_redirect_post_location_filter()
     * 
     * Adds 102 as a value for message in the query string
     * 
     * @param mixed $location
     * @return string
     */
    public function my_redirect_post_location_filter($location) {

        remove_filter('redirect_post_location', __function__, 102);

        $location = add_query_arg('message', 102, $location);

        return $location;

    } // end public function my_redirect_post_location_filter($location) {

    /**
     * Content_Type::my_post_admin_notices()
     * 
     * Diplays any error messages
     * 
     * @return string
     */
    public function my_post_admin_notices() {

        if (!isset($_GET['message'])) return;

        if ($_GET['message'] == '102') {

            global $post;

            // abort if not my custom type
            if ($post->post_type != 'jobs') return $post->ID;

            $message = '<div id="notice" class="error"><p>';
            $message .= "Error: please check that all form values are correct - <br>";
            $message .= isset($_SESSION['error']) ? implode('<br>', unserialize($_SESSION['error'])) : null;
            $message .= '</p></div>';
            echo $message;

            unset($_SESSION['error']);

        } // end if

    } // end public function my_post_admin_notices() {
} // end class

new \content\Content_Type_Jobs_Template;


// It can be used in the theme like so:

if (class_exists('\\content\\Content_Type_Jobs_Template')) {

    $meta = get_post_meta($id);

    $table = '<table>
<caption>Current vacancies</caption>
<tr class="header-row">
<td id="job-title">Title</td>
<td id="job-description">Description</td>
<td id="job-location">Location</td>
<td id="job-date">Date posted</td>
</tr>';

    $array_keys = array_keys(\content\Content_Type_Jobs_Template::metabox_attributes());

    // loop through metabox jobs content to create the table data

    foreach ($meta as $key => $value) {

        // make sure that all returned keys fit the original keys in the metabox_attributes method
        if (!in_array(preg_replace('/\d/', '', $key), $array_keys))
            continue;

        static $i;
        $number = $i++;

        if ($number % (count($array_keys)) == 0) {
            $table .= '<tr>';
        }

        if (stristr($key, $array_keys['0'])) {
            $table .= '<td headers="job-title">' . implode('', $value) . '</td>';
        }

        if (stristr($key, $array_keys['1'])) {
            $table .= '<td headers="job-description">' . implode('', $value) . '</td>';
        }

        if (stristr($key, $array_keys['2'])) {
            $table .= '<td headers="job-location">' . implode('', $value) . '</td>';
        }

        if (stristr($key, $array_keys['3'])) {
            $table .= '<td headers="job-date">' . implode('', $value) . '</td>';
        }

        if (($number - (count($array_keys) - 1)) % (count($array_keys)) == 0) {
            $table .= '</tr>';
        }

    } // end foreach

    $table .= '</table>';

    echo $table;

} // end if  if (class_exists('\\menu\\Content_Type_Jobs_Template'))