Example How To Add Meta Boxes To Edit Area

Additional fields, meta boxes, in the edit area of WordPress often are useful and easier for customers instead of using Custom Fields. A small Plugin will show you three options. Use it, make WordPress even better for your clients. Learn how easy it is to adjust the edit area in WordPress.

This Plugin adds 3 new field in a meta box:

• Subtitle – a line without formatting
• Additional information – a complete editor, you can even add attachments, it’s almost like the standard content editor.
• List data – It’s possible to put in each line content, which will displayed as an unordered list. ul

Each of these fields can be used in a theme template, since it has a template tag, which controlls the output. Only if you have data in a field it will be displayed. The following example will output the 3 fields.

 id="post-">

    


    
ID, 'heading'); ?>

    


        Read the rest of this entry »
'); ?>

        ID, 'additional-info'); ?>

        ID, 'listdata'); ?>

This Plugin should be just an example, if you like it, you can adjust it to your liking. So you can provide a nice backend for your authors, without custom fields.

The Plugin takes care, that the meta boxes “Custom Fields” and “Trackbacks” aren’t there anymore (remove_meta_box()); just another example for the usage of this Plugin. Here is the code and below you can find the link to download the Plugin, including readme, language file for German users and the necessary scripts.

ID); ?>
 * @param $id Integer - Post-ID
 * @param $type String - heading, additional-info, listdata (default is ''-empty)
 *
 * Example: ID, 'heading'); ?>
 */

//avoid direct calls to this file, because now WP core and framework has been used
if ( !function_exists('add_action') ) {
    header('Status: 403 Forbidden');
    header('HTTP/1.1 403 Forbidden');
    exit();
}

if ( function_exists('add_action') ) {
    //WordPress definitions
    if ( !defined('WP_CONTENT_URL') )
        define('WP_CONTENT_URL', get_option('siteurl') . '/wp-content');
    if ( !defined('WP_CONTENT_DIR') )
        define('WP_CONTENT_DIR', ABSPATH . 'wp-content');
    if ( !defined('WP_PLUGIN_URL') )
        define('WP_PLUGIN_URL', WP_CONTENT_URL.'/plugins');
    if ( !defined('WP_PLUGIN_DIR') )
        define('WP_PLUGIN_DIR', WP_CONTENT_DIR.'/plugins');
    if ( !defined('PLUGINDIR') )
        define( 'PLUGINDIR', 'wp-content/plugins' ); // Relative to ABSPATH.  For back compat.
    if ( !defined('WP_LANG_DIR') )
        define('WP_LANG_DIR', WP_CONTENT_DIR . '/languages');

    // plugin definitions
    define( 'FB_DT_BASENAME', plugin_basename(__FILE__) );
    define( 'FB_DT_BASEDIR', dirname( plugin_basename(__FILE__) ) );
    define( 'FB_DT_TEXTDOMAIN', 'different-types' );
}

if ( !class_exists( 'DifferentType' ) ) {
    class DifferentType {

        // constructor
        function DifferentType() {

            if (is_admin() ) {
                add_action( 'admin_init', array(&$this, 'on_admin_init') );
                add_action( 'wp_insert_post', array(&$this, 'on_wp_insert_post'), 10, 2 );
                add_action( 'init', array(&$this, 'textdomain') );
                register_uninstall_hook( __FILE__, array(&$this, 'uninstall') );
                add_action( "admin_print_scripts-post.php", array($this, 'enqueue_script') );
                add_action( "admin_print_scripts-post-new.php", array($this, 'enqueue_script') );
                add_action( "admin_print_scripts-page.php", array($this, 'enqueue_script') );
                add_action( "admin_print_scripts-page-new.php", array($this, 'enqueue_script') );
            }
        }

        // active for multilanguage
        function textdomain() {

            if ( function_exists('load_plugin_textdomain') )
                load_plugin_textdomain( FB_DT_TEXTDOMAIN, false, dirname( FB_DT_BASENAME ) . '/languages' );
        }

        // unsintall all postmetadata
        function uninstall() {

            $all_posts = get_posts('numberposts=0&post_type=post&post_status=');

            foreach( $all_posts as $postinfo) {

                delete_post_meta($postinfo->ID, '_different-types');

            }
        }

        // add script
        function enqueue_script() {
            wp_enqueue_script( 'tinymce4dt', WP_PLUGIN_URL . '/' . FB_DT_BASEDIR . '/js/script.js', array('jquery') );
        }

        // admin init
        function on_admin_init() {

            if ( !current_user_can( 'publish_posts' ) )
                return;

            add_meta_box( 'different_types',
                                    __( 'Different Types', FB_DT_TEXTDOMAIN ),
                                    array( &$this, 'meta_box' ),
                                    'post', 'normal', 'high'
                                    );

            // remove meta box for trackbacks
            remove_meta_box('trackbacksdiv', 'post', 'normal');
            // remove meta box for custom fields
            remove_meta_box('postcustom', 'post', 'normal');
        }

        // check for preview
        function is_page_preview() {
            $id = (int)$_GET['preview_id'];
            if ($id == 0) $id = (int)$_GET['post_id'];
            $preview = $_GET['preview'];
            if ($id > 0 && $preview == 'true') {
                global $wpdb;
                $type = $wpdb->get_results("SELECT post_type FROM $wpdb->posts WHERE ID=$id");
                if ( count($type) && ($type[0]->post_type == 'page') && current_user_can('edit_page') )
                    return true;
            }
            return false;
        }

        // after save post, save meta data for plugin
        function on_wp_insert_post($id) {
            global $id;

            if ( !isset($id) )
                $id = (int)$_REQUEST['post_ID'];
            if ( $this->is_page_preview() && !isset($id) )
                $id = (int)$_GET['preview_id'];

            if ( !current_user_can('edit_post') )
                return;

            if ( isset($_POST['dt-heading']) && $_POST['dt-heading'] != '' )
                $this->data['heading'] = esc_attr( $_POST['dt-heading'] );
            if ( isset($_POST['dt-additional-info']) && $_POST['dt-additional-info'] != '' )
                $this->data['additional-info'] = $_POST['dt-additional-info'];
            if ( isset($_POST['dt-listdata']) && $_POST['dt-listdata'] != '' )
                $this->data['listdata'] = esc_attr( $_POST['dt-listdata'] );

            if ( isset($this->data) && $this->data != '' )
                update_post_meta($id, '_different-types', $this->data);
        }

        // load post_meta_data
        function load_post_meta($id) {

            return get_post_meta($id, '_different-types', true);
        }

        // meta box on post/page
        function meta_box($data) {

            $value = $this->load_post_meta($data->ID);
            ?>
            

                

                    

                    

                
                

                    

                    
<?php echo wpautop( $value['additional-info'] ); ?>
                        
                    
                
                

                    

                    
<?php echo $value['listdata']; ?>

                
            
             $listdata ) {

                    $return .= '
' . trim($listdata) . '
';

                }
                return '
' . $return . '
'. "\n";
            }
        }

        // echo facts, if exists
        function DifferentTypeFacts($id, $type, $string) {

            if ( $id ) {
                $value = $this->load_post_meta($id);

                echo $this->get_DifferentTypeFacts($id, $type, $value);
            }
        }

    } // End class

    // instance class
    $DifferentType = new DifferentType();

    // use in template
    function the_DifferentTypeFacts($id, $type = '', $string = '') {
        global $DifferentType;

        $DifferentType->DifferentTypeFacts($id, $type, $string);
    }

} // End if class exists statement
?>

You can find the complete Plugin at github.