Sample Meta Box

meta-box-sample.php

<?php

/* 1. Back End Usage
---------------------------------------------------------------------*/

// add neccessary actions
// @see http://codex.wordpress.org/Function_Reference/add_action
add_action( 'add_meta_boxes', 'rg_add_custom_box' );
add_action( 'save_post', 'rg_save_postdata', 10, 1 );

/**
 * Adds a box to the main column on the Post edit screen 
 * 
 * @hook add_meta_boxes
 * @see http://codex.wordpress.org/Function_Reference/add_meta_box 
 */
function rg_add_custom_box() {
  add_meta_box(
			'rg_sectionid', __( 'WP Editor Meta Box', 'rg_textdomain' ), 'rg_inner_custom_box', 'post'
	);
}

/**
 * Function that renders the Meta Box 
 * called as the 3rd parameter of add_meta_box
 */
function rg_inner_custom_box($post) {

	// Use nonce for verification
	wp_nonce_field( plugin_basename( __FILE__ ), 'rg_noncename' );

	// The actual fields for data entry
	$meta = get_post_meta( $post->ID, 'rg_wp_editor_sample', true );
	?>
	<?php

	$content = $meta ? $meta['es'] : '';
	
	// provide textarea name for $_POST variable
	$args = array(
		'textarea_name' => 'rg_wp_editor_sample',
	);
	// render wp_editor with custom arguments
	wp_editor( $content, 'rg_wp_editor_sample', $args );
	?>

	<?php

}

/**
 * When the post is saved, save our custom data 
 * 
 * @hook save_post
 */
function rg_save_postdata($post_id) {

	// check if we're on the general post (post, page, cpt, etc.) page and if the nonce has been set
	if ( !isset( $_POST['post_type'] ) or !isset( $_POST['rg_noncename'] ) ) {
		return;
	}
	
	// check if the we're on the post page
	if ( !in_array( $_POST['post_type'], array( 'post' ) ) ) {
		return;
	}

	// if we're doing an auto save return
	if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE )
		return;

	// verify nonce for the safety reasones
	// @see http://codex.wordpress.org/WordPress_Nonces
	if ( !wp_verify_nonce( $_POST['rg_noncename'], plugin_basename( __FILE__ ) ) )
		return;

	// make sure that current user has proper rights to save the post
	// @see http://codex.wordpress.org/Roles_and_Capabilities
	if ( !current_user_can( 'edit_post', $post_id ) )
		return;


	// get the data from the $_POST
	$es = $_POST['rg_wp_editor_sample'];


	// store the meta as an array in case something else was added later on
	$meta = array(
		'es' => $es,
	);

	update_post_meta( $post_id, 'rg_wp_editor_sample', $meta );
}

/* 2. Front End Usage
--------------------------------------------------------------------------------*/

// use within the loop
// @see http://codex.wordpress.org/The_Loop
$meta = get_post_meta( $post->ID, 'rg_wp_editor_sample', true );
echo isset($meta['es']) ? apply_filters('the_content', $meta['es']) : 'no Meta Box meta saved';