Simple Meta Box Helper Class

meta-box-class.php

<?php
/* Prevent loading this file directly and/or if the class is already defined */
if ( ! defined( 'ABSPATH' ) || class_exists( 'SC_Plugin_Meta_Box_Class' ) )
	return;


/**
 * Shellcreeper Meta Boxes Class
 * Helper class to easily create meta boxes in post edit screen with Meta Box API.
 * Rename this class name if you use it in your plugin/theme.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * @version 0.1.0
 * @author David Chandra Purnama <david@shellcreeper.com>
 * @link http://shellcreeper.com
 * @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * @copyright Copyright (c) 2013, David Chandra Purnama
 */
class SC_Plugin_Meta_Box_Class{

	/**
	 * @var $config the config for the meta box created
	 * @access public
	 */
	var $config;

	/**
	 * Class Constructor
	 * @param array $config the configuration required for the updater to work
	 * @return void
	 */
	public function __construct( $config = array() ) {

		/* Default config. */
		$defaults = array(
			'id'                  => '',                 // unique meta box id
			'title'               => '',                 // meta box title
			'callback'            => '',                 // meta box callback
			'post_types'          => array( 'post' ),    // $screen
			'context'             => 'normal',           // 'normal', 'advanced', or 'side'
			'priority'            => 'default',          // 'high', 'core', 'default' or 'low'
			'callback_args'       => null,               // callback args in array()
			'save_callback'       => '',                 // save post callback function
			'nonce'               => '',                 // nonce string
			'meta_keys'           => array(),            // meta keys config
			'style'               => 'margin-top:-6px;'  // wrapper style
		);

		/* Merge configs and defaults. */
		$this->config = wp_parse_args( $config, $defaults );
		$config = $this->config;

		/* Only load if config ID and Title is not empty. */
		if ( $config['id'] !== '' && $config['title'] !== '' ){

			/* If meta keys is not empty. */
			if ( !empty( $config['meta_keys'] ) ){

				/* Load register meta function */
				add_action( 'init', array( &$this, 'register_meta' ) );
			}

			/* Load meta box setup */
			add_action( 'admin_init', array( &$this, 'load_meta_boxes' ) );
		}
	}

	/**
	 * Register meta for sanitazion
	 * @return void
	 */
	public function register_meta(){

		/* Get config */
		$config = $this->config;

		/* Only if meta_keys not empty, and is array */
		if ( !empty( $config['meta_keys'] ) && is_array( $config['meta_keys'] ) ){

			/* For each meta keys */
			foreach( $config['meta_keys'] as $meta_key_data ){

				/* For each post types */
				foreach( $config['post_types'] as $post_type ){

					/* Register meta */
					register_meta( $post_type, $meta_key_data['key'], $meta_key_data['sanitize'] );
				}
			}
		}
	}

	/**
	 * Load Meta Box
	 * @return void
	 */
	public function load_meta_boxes(){

		/* Fire our meta box setup function on the post editor screen. */
		add_action( 'load-post.php', array( &$this, 'setup_meta_boxes' ) );
		add_action( 'load-post-new.php', array( &$this, 'setup_meta_boxes' ) );
	}

	/**
	 * Setup Meta Box
	 * @return void
	 */
	public function setup_meta_boxes(){

		/* Get config */
		$config = $this->config;

		/* Save Callback function */
		$save_callback = array( &$this, 'save_callback' );
		if ( !empty( $config['save_callback'] ) && function_exists( $config['save_callback'] ) ){
			$save_callback = $config['save_callback'];
		}

		/* Add meta boxes on the 'add_meta_boxes' hook. */
		add_action( 'add_meta_boxes', array( &$this, 'add_meta_boxes' ), 10, 2 );

		/* Save post meta on the 'save_post' hook. */
		add_action( 'save_post', $save_callback, 10, 2 );

		/* Save attachment meta. */
		if ( in_array( 'attachment', $config['post_types'] ) ) {

			add_action( 'add_attachment', $save_callback, 10, 2 );
			add_action( 'edit_attachment', $save_callback, 10, 2 );
		}
	}

	/**
	 * Add Meta Box
 	 * @return void
	 */
	public function add_meta_boxes( $post_type, $post ) {

		/* Get config */
		$config = $this->config;

		/* Calback function. */
		$callback = array( &$this, 'callback' );
		if ( !empty( $config['callback'] ) && function_exists( $config['callback'] ) ){
			$callback = $config['callback'];
		}

		/* Check post type and user caps. */
		if ( ( in_array( $post_type, $config['post_types'] ) ) && ( current_user_can( 'edit_post_meta', $post->ID ) || current_user_can( 'add_post_meta', $post->ID ) || current_user_can( 'delete_post_meta', $post->ID ) ) ){

			/* Add Meta Box */
			add_meta_box( $config['id'], $config['title'], $callback, $post_type, $config['context'], $config['priority'] );
		}
	}

	/**
	 * Callback Function
 	 * @return void
	 */
	public function callback( $post, $box ) {

		/* Get config */
		$config = $this->config;

		/* Open Wrapper */
		echo '<div id="' . sanitize_html_class( $config['id'] ) . '-meta-box" class="sc-mb-wrap" style="' . $config['style']. '">';

		/* Nonce */
		wp_nonce_field( basename( __FILE__ ), $config['nonce'] );

		/* Foreach meta key, create fields */
		foreach( $config['meta_keys'] as $meta_key_id => $meta_key_data ){

			/* Sanitize ID */
			$meta_key_id = sanitize_html_class( $meta_key_id );

			/* Default value */
			$default = '';
			if( isset( $meta_key_data['default'] ) ){
				$default = $meta_key_data['default'];
			}

			/* Multiple value in one key */
			if ( is_array( $default ) ){
				$post_meta_data = get_post_meta( $post->ID, $meta_key_data['key'], false );
				$value = array();
				if ( !empty( $post_meta_data ) ){
					$value = $post_meta_data;
				}
				elseif( !empty( $default ) ){
					$value = $default;
				}
			}

			/* Single value */
			else{
				$post_meta_data = get_post_meta( $post->ID, $meta_key_data['key'], true );
				$value = '';
				if ( !empty( $post_meta_data ) ){
					$value = $post_meta_data;
				}
				elseif( !empty( $default ) ){
					$value = $default;
				}
			}

			$title = ( isset( $meta_key_data['title'] ) ? $meta_key_data['title'] : '' );
			$desc = ( isset( $meta_key_data['desc'] ) ? $meta_key_data['desc'] : '' );
			$class = ( isset( $meta_key_data['class'] ) ? $meta_key_data['class'] : '' );
			$label = ( isset( $meta_key_data['label'] ) ? esc_attr( $meta_key_data['label'] ) : '' );
			$wrap_class = ( isset(  $meta_key_data['wrap_class'] ) ?  $meta_key_data['wrap_class'] : '' );
			$wrap_class = esc_attr( $wrap_class );
			$wrap_class = ( !empty( $wrap_class ) ? $wrap_class : 'misc-pub-section' );
			$wrap_open  = '<div id="' . $meta_key_id . '-wrap" class="' . $wrap_class . '">';
			$wrap_close = '</div>';

			/* Render field based on 'type' */
			switch ( $meta_key_data['type'] ) {

				/* Custom */
				case 'custom':
					if ( isset( $meta_key_data['type_callback'] ) && !empty( $meta_key_data['type_callback'] ) && function_exists( $meta_key_data['type_callback'] ) ){
						call_user_func( $meta_key_data['type_callback'], array( 
							'post' => $post,
							'box' => $box,
							'meta_key_data' => $meta_key_data
						));
					}
					break;

				/* Checkbox */
				case 'checkbox':
					$checkbox_value = ( isset( $meta_key_data['value'] ) ? esc_attr( $meta_key_data['value'] ) : '1' );
					echo $wrap_open;
					echo $title;
					echo '<input type="checkbox" name="' . $meta_key_data['name'] . '" value="' . $checkbox_value . '"  class="' . $class . '" id="' . $meta_key_id . '" ' . checked( $value, $checkbox_value, false ) . '/>';
					if( !empty( $label ) ) echo ' <label for="' . $meta_key_id . '">' . $label . '</label>';
					echo $desc;
					echo $wrap_close;
					break;

				/* Text */
				case 'text':
					echo $wrap_open;
					echo $title;
					if( !empty( $label ) ) echo ' <label for="' . $meta_key_id . '">' . $label . '</label>' . '<br/>';
					echo '<input type="text" name="' . $meta_key_data['name'] . '" class="' . $class . '" id="' . $meta_key_id . '" value="' . $value . '"/>';
					echo $desc;
					echo $wrap_close;
					break;

				/* Textarea */
				case 'textarea':
					$cols = ( isset( $meta_key_data['cols'] ) ? esc_attr( $meta_key_data['cols'] ) : '60' );
					$rows = ( isset( $meta_key_data['rows'] ) ? esc_attr( $meta_key_data['rows'] ) : '5' );
					echo $wrap_open;
					echo $title;
					if( !empty( $label ) ) echo ' <label for="' . $meta_key_id . '">' . $label . '</label>';
					echo '<textarea name="' . $meta_key_data['name'] . '" class="' . $class . '" id="' . $meta_key_id . '" cols="' . $cols . '" rows="' . $rows . '">' . $value . '</textarea>';
					echo $desc;
					echo $wrap_close;
					break;

				/* Select */
				case 'select':
					echo $wrap_open;
					echo $title;
					if( !empty( $label ) ) echo ' <label for="' . $meta_key_id . '">' . $label . '</label><br />';
					echo '<select name="' . $meta_key_data['name'] . '" class="' . $class . '" id="' . $meta_key_id . '">';
					foreach ( $meta_key_data['options'] as $option ) {
						echo '<option id="' . $option['id'] . '" value="' . $option['value'] . '" ' . selected( $value, $option['value'], false ) . '>' . $option['label'] . '</option>';
					}
					echo '</select>';
					echo $desc;
					echo $wrap_close;
					break;

				/* Radio */
				case 'radio':
					echo $wrap_open;
					echo $title;
					echo '<ul id="' . $meta_key_id . '" class="' . $class . '">';
					foreach ( $meta_key_data['options'] as $option ) {
						echo '<li>';
						echo '<input value="' . $option['value'] . '" type="radio" name="' . $meta_key_data['name'] . '" id="' . $option['id'] . '" ' . checked( $value, $option['value'], false ) . '/>';
						echo ' <label for="' . $option['id'] . '">' . $option['label'] . '</label>';
						echo '</li>';
					}
					echo '</ul>';
					echo $desc;
					echo $wrap_close;
					break;

				/* Multicheck: using multiple data in the same key */
				case 'multicheck':
					if ( is_array( $default ) ){
						echo $wrap_open;
						echo $title;
						echo '<ul id="' . $meta_key_id . '" class="' . $class . '">';
						foreach ( $meta_key_data['options'] as $option ) {
							$checked = in_array( $option['value'], $value ) ?  'checked="checked"' : '';
							echo '<li>';
							echo '<input value="' . $option['value'] . '" type="checkbox" name="' . $meta_key_data['name'] . '[]' . '" id="' . $option['id'] . '" ' . $checked . '>';
							echo ' <label for="' . $option['id'] . '">' . $option['label'] . '</label>';
							echo '</li>';
						}
						echo '</ul>';
						echo $desc;
						echo $wrap_close;
					}
					break;
			}
		}
		/* Close Wrapper */
		echo '</div>';
	}

	/**
	 * Save Callback Function
 	 * @return void
	 */
	public function save_callback( $post_id, $post = '' ) {

		/* Get config */
		$config = $this->config;

		/* Fix for attachment save issue in WordPress 3.5. @link http://core.trac.wordpress.org/ticket/21963 */
		if ( !is_object( $post ) ){
			$post = get_post();
		}

		/* Verify the nonce before proceeding. */
		if ( !isset( $_POST[$config['nonce']] ) || !wp_verify_nonce( $_POST[$config['nonce']], basename( __FILE__ ) ) ){
			return $post_id;
		}

		/* Return on auto save, ajax, cron */
		if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE )
			return;
		if ( defined( 'DOING_AJAX' ) && DOING_AJAX )
			return;
		if ( defined( 'DOING_CRON' ) && DOING_CRON )
			return;
		if ( 'revision' === $post->post_type )
			return;


		/* Get the post type object. */
		$post_type = get_post_type_object( $post->post_type );

		/* Check if the current user has permission to edit the post. */
		if ( !current_user_can( $post_type->cap->edit_post, $post_id ) ){
			return $post_id;
		}
		/* Foreach meta key, create fields */
		foreach( $config['meta_keys'] as $meta_key_id => $meta_key_data ){
		
			/* Get the meta key. */
			$meta_key = $meta_key_data['key'];

			/* Defaults */
			$default = '';
			if( isset( $meta_key_data['default'] ) ){
				$default = $meta_key_data['default'];
			}

			/* Custom validation/save post
			------------------------------------- */
			if ( isset( $meta_key_data['validate'] ) && !empty( $meta_key_data['validate'] ) && function_exists( $meta_key_data['validate'] ) ){
				call_user_func( $meta_key_data['validate'], array( 
					'post_id' => $post_id,
					'post' => $post,
					'meta_key_data' => $meta_key_data
				));
			}

			/* Multiple data in one key
			------------------------------------- */
			elseif ( is_array( $default ) ){

				/* Get the previous post meta. */
				$meta_values = get_post_meta( $post_id, $meta_key, false );

				/* Get the submitted post meta. */
				$new_meta_values = ( isset( $_POST[$meta_key_data['name']] ) ? $_POST[$meta_key_data['name']] : array() );

				/* First delete all data. */
				if ( current_user_can( 'delete_post_meta', $post_id, $meta_key ) ){
					delete_post_meta( $post_id, $meta_key );
				}
				/* Only add if new data is not empty */
				if ( current_user_can( 'add_post_meta', $post_id, $meta_key ) && !empty( $new_meta_values ) ) {
					foreach ( $new_meta_values as $new_meta_value ) {
						add_post_meta( $post_id, $meta_key, $new_meta_value, false );
					}
				}

			}

			/* Only single data in one key
			------------------------------------- */
			else{

				/* Get the previous post meta. */
				$meta_value = get_post_meta( $post_id, $meta_key, true );

				/* Get the submitted post meta. */
				$new_meta_value = ( isset( $_POST[$meta_key_data['name']] ) ? $_POST[$meta_key_data['name']] : '' );

				/* If there is no new meta value but an old value exists, delete it. */
				if ( current_user_can( 'delete_post_meta', $post_id, $meta_key ) && '' == $new_meta_value && $meta_value ){
					delete_post_meta( $post_id, $meta_key, $meta_value );
				}

				/* If a new meta value was added and there was no previous value, add it. */
				elseif ( current_user_can( 'add_post_meta', $post_id, $meta_key ) && $new_meta_value && '' == $meta_value ){
					add_post_meta( $post_id, $meta_key, $new_meta_value, true );
				}

				/* If the old meta doesn't match the new meta, update the post meta. */
				elseif ( current_user_can( 'edit_post_meta', $post_id, $meta_key ) && $meta_value !== $new_meta_value ){
					update_post_meta( $post_id, $meta_key, $new_meta_value );
				}
			}
		}
	}

} // end class