When saving custom fields from a custom metabox, if the value is empty, usually the custom field is deleted. This is good, as it keeps from having lots of empty entries in the database.

However, it means that when you update from the “Quick Edit” menu, since your custom fields are not in the form, they will disappear. Not so good.

Here’s the fix.  Add this to your save function for the metabox:

//Don't update on Quick Edit
if (defined('DOING_AJAX') ) {
    return $post_id;
}

 So, your save function should look something like this:

add_action('save_post', 'lt_art_save_data');

function lt_art_save_data($post_id) {
    global $art_meta_box, $post ;
    
    //Verify nonce
    if (isset($_POST['lt_art_meta_box_nonce']) && !wp_verify_nonce($_POST['lt_art_meta_box_nonce'], basename(__FILE__))) {
        return $post_id;
    }

    //Check autosave
    if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) {
        return $post_id;
    }
	
    //Don't update on Quick Edit
    if (defined('DOING_AJAX') ) {
	return $post_id;
    }
		
    //Check permissions
    if ('page' == $_POST['post_type']) {
        if (!current_user_can('edit_page', $post_id)) {
            return $post_id;
        }
    } elseif (!current_user_can('edit_post', $post_id)) {
        return $post_id;
    }
	
    foreach ($art_meta_box['lt_art']['fields'] as $field) {
        $old = get_post_meta($post_id, $field['id'], true);
        $new = $_POST[$field['id']];
        
        if ($new && $new != $old) {
            update_post_meta($post_id, $field['id'], $new);
        } elseif ('' == $new && $old) {
            delete_post_meta($post_id, $field['id'], $old);
        }
    }
}

I created this simple plugin for a restaurant to post their menu online.

Here’s the plugin file (put in plugins directory).

It includes categories (for menu sections), and several parameters for each item.

<?php
/*
Plugin Name: Grille Menu
Description: Custom Post Type for Menu Items
Author: Diana Nichols
Version: 1.0
Author URI: http://www.lavenderthreads.com
*/

add_action( 'init', 'register_grille_menu' );

function register_grille_menu() {

    $labels = array( 
        'name' => _x( 'Grille Menu', 'menu' ),
        'singular_name' => _x( 'Grille Menu Item', 'menu' ),
        'add_new' => _x( 'Add New', 'menu' ),
        'add_new_item' => _x( 'Add New Menu Item', 'menu' ),
        'edit_item' => _x( 'Edit Item', 'menu' ),
        'new_item' => _x( 'New Item', 'menu' ),
        'view_item' => _x( 'View Item', 'menu' ),
        'search_items' => _x( 'Search Items', 'menu' ),
        'not_found' => _x( 'No items found', 'menu' ),
        'not_found_in_trash' => _x( 'No items found in Trash', 'menu' ),
        'parent_item_colon' => _x( 'Parent Item:', 'menu' ),
        'menu_name' => _x( 'Grille Menu', 'menu' ),
    );

    $args = array( 
        'labels' => $labels,
        'hierarchical' => false,        
        'supports' => array( 'title', 'editor', 'page-atributes' ),
        'public' => true,
        'show_ui' => true,
        'show_in_menu' => true,   
        'show_in_nav_menus' => true,
        'publicly_queryable' => true,
        'exclude_from_search' => false,
        'has_archive' => true,
        'query_var' => true,
        'can_export' => true,
        'rewrite' => true,
        'capability_type' => 'post'
    );

    register_post_type( 'grille_menu', $args );
}

add_action( 'init', 'register_grille_taxonomy_categories' );

function register_grille_taxonomy_categories() {

    $labels = array( 
        'name' => _x( 'Grille Categories', 'categories' ),
        'singular_name' => _x( 'Category', 'categories' ),
        'search_items' => _x( 'Search Categories', 'categories' ),
        'popular_items' => _x( 'Popular Categories', 'categories' ),
        'all_items' => _x( 'All Categories', 'categories' ),
        'parent_item' => _x( 'Parent Category', 'categories' ),
        'parent_item_colon' => _x( 'Parent Category:', 'categories' ),
        'edit_item' => _x( 'Edit Category', 'categories' ),
        'update_item' => _x( 'Update Category', 'categories' ),
        'add_new_item' => _x( 'Add New Category', 'categories' ),
        'new_item_name' => _x( 'New Category', 'categories' ),
        'separate_items_with_commas' => _x( 'Separate categories with commas', 'categories' ),
        'add_or_remove_items' => _x( 'Add or remove categories', 'categories' ),
        'choose_from_most_used' => _x( 'Choose from the most used categories', 'categories' ),
        'menu_name' => _x( 'Categories', 'categories' ),
    );

    $args = array( 
        'labels' => $labels,
        'public' => true,
        'show_in_nav_menus' => true,
        'show_ui' => true,
        'show_tagcloud' => true,
        'show_admin_column' => true,
        'hierarchical' => true,
        'rewrite' => true,
        'query_var' => true
    );

    register_taxonomy( 'grille_categories', array('grille_menu'), $args );
}

// the custom fields
add_action('admin_menu', 'lt_grille_add_box'); 

$prefix = 'grille_menu_';

$grille_meta_box['grille_menu'] = array(
    'id' => 'grille-menu-meta-details',
    'title' => 'Menu Item Information',
    'context' => 'side',
    'priority' => 'default',
    'fields' => array(
		array(
		'name' => 'Price 1',
		'id' => $prefix . 'price1',
		'type' => 'text',
		'desc' => '',
		'default' => '',
		'class' => '',
		),
		array(
		'name' => 'Price Label 1',
		'id' => $prefix . 'pricelabel1',
		'type' => 'text',
		'desc' => '',
		'default' => '',
		'class' => '',
		),
		array(
		'name' => 'Price 2',
		'id' => $prefix . 'price2',
		'type' => 'text',
		'desc' => '',
		'default' => '',
		'class' => '',
		),
		array(
		'name' => 'Price Label 2',
		'id' => $prefix . 'pricelabel2',
		'type' => 'text',
		'desc' => '',
		'default' => '',
		'class' => '',
		),
		array(
		'name' => 'Signature Item',
		'id' => $prefix . 'signature',
		'type' => 'checkbox',
		'desc' => '',
		'default' => '',
		'class' => '',
		),
		array(
		'name' => 'Menu Order',
		'id' => $prefix . 'order',
		'type' => 'text',
		'desc' => '',
		'default' => '1',
		'class' => '',
		),
    )
);

//Add meta boxes to post types
function lt_grille_add_box() {
    global $grille_meta_box;
    
    foreach($grille_meta_box as $post_type => $value) {
        add_meta_box($value['id'], $value['title'], 'lt_grille_format_box', $post_type, $value['context'], $value['priority']);
    }
}

//Format meta boxes
function lt_grille_format_box() {
  global $grille_meta_box, $post;

  // Use nonce for verification
  echo '<input type="hidden" name="lt_grille_meta_box_nonce" value="', wp_create_nonce(basename(__FILE__)), '" />';

  echo '<table class="form-table">';

  foreach ($grille_meta_box[$post->post_type]['fields'] as $field) {
      // get current post meta data
      $meta = get_post_meta($post->ID, $field['id'], true);

      echo '<tr>'.
              '<th style="width:20%"><label for="'. $field['id'] .'">'. $field['name']. '</label></th>'.
              '<td>';
      switch ($field['type']) {
          case 'text':
              echo '<input type="text" name="'. $field['id']. '" id="'. $field['id'] .'" value="'. ($meta ? $meta : $field['default']) . '" size="30" style="width:97%" class= "' .$field['class']. '" />'. '<br />'. $field['desc'];
              break;
          case 'textarea':
              echo '<textarea name="'. $field['id']. '" id="'. $field['id']. '" cols="60" rows="4" style="width:97%">'. ($meta ? $meta : $field['default']) . '</textarea>'. '<br />'. $field['desc'];
              break;
          case 'select':
              echo '<select name="'. $field['id'] . '" id="'. $field['id'] . '">';
              foreach ($field['options'] as $option) {
                  echo '<option '. ( $meta == $option ? ' selected="selected"' : '' ) . '>'. $option . '</option>';
              }
              echo '</select>';
              break;
          case 'radio':
              foreach ($field['options'] as $option) {
                  echo '<input type="radio" name="' . $field['id'] . '" value="' . $option['value'] . '"' . ( $meta == $option['value'] ? ' checked="checked"' : '' ) . ' />' . $option['name'];
              }
              break;
          case 'checkbox':
              echo '<input type="checkbox" name="' . $field['id'] . '" id="' . $field['id'] . '"' . ( $meta ? ' checked="checked"' : '' ) . ' />';
              break;
      }
      echo     '<td>'.'</tr>';
  }

  echo '</table>';

}

// Save data from meta box
function lt_grille_save_data($post_id) {
    global $grille_meta_box,  $post;
    
    //Verify nonce
    if (!wp_verify_nonce($_POST['lt_grille_meta_box_nonce'], basename(__FILE__))) {
        return $post_id;
    }

    //Check autosave
    if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) {
        return $post_id;
    }

    //Don't update on Quick Edit save
    if (defined('DOING_AJAX') ) {
	return $post_id;
	}

    //Check permissions
    if ('page' == $_POST['post_type']) {
        if (!current_user_can('edit_page', $post_id)) {
            return $post_id;
        }
    } elseif (!current_user_can('edit_post', $post_id)) {
        return $post_id;
    }
    
    foreach ($grille_meta_box[$post->post_type]['fields'] as $field) {
        $old = get_post_meta($post_id, $field['id'], true);
        $new = $_POST[$field['id']];
        
        if ($new && $new != $old) {
            update_post_meta($post_id, $field['id'], $new);
        } elseif ('' == $new && $old) {
            delete_post_meta($post_id, $field['id'], $old);
        }
    }
}

add_action('save_post', 'lt_grille_save_data');

Now here’s the menu category display page. Create a page named “archive-grille_menu.php” and upload to your theme directory. Replace the loop with this code:

(I listed the categories in two columns.)

	$args2 = array(	'orderby' => 'name',	'order' => 'ASC',	'style' => 'none',	'taxonomy' => 'grille_categories',	'echo' => 0,'title_li'  =>'' );
	$cats = explode("<br />",wp_list_categories($args2));
	$cat_n = count($cats) - 1;
	$cat_left='';
	$cat_right= '';
	for ($i=0;$i<$cat_n;$i++):
		if ($i<$cat_n/2):
			$cat_left = $cat_left.'<li>'.$cats[$i].'</li>';
		elseif ($i>=$cat_n/2):
			$cat_right = $cat_right.'<li>'.$cats[$i].'</li>';
		endif;
	endfor;
	?>

 Next is the display page for each category:

Remember to change the divs and styling to match your page layout.

 $meta['grille_menu_price2'][0];
			$label2= $meta['grille_menu_pricelabel2'][0];
			$sig=$meta['grille_menu_signature'][0];
			?>
			<div class="menuitem<?php if($count %2 == 0) echo ' odd' ?>">
				<div class="itemname">
					<h3><?php if ($sig) { ?><img src="<?php bloginfo('template_directory') ?>/images/sig-icon.png" style="display:inline-block"> <?php } the_title(); ?></h3>
					<div class="itemdesc"><?php the_content(); ?></div>
				</div>
				<div class="prices">
				<div class="price1">
					<?php if (!empty($label1)) {
						echo  '<p>'.$label1. '</p>';
						}
						echo '<strong>'.$price1.'</strong>'; ?>
				</div>
				<div class="price2">
					<?php if( !empty($price2)) {
						if (!empty($label2)) {
							echo '<p>'.$label2. '</p>';
						}
						echo '<strong>'.$price2.'</strong>';
					}?>
				</div>
				</div>
			</div>
		<?php endwhile; endif; 
		wp_reset_query() ?>
		</div>
		</div>

	</div>

 You can see this plugin in action at: http://paradisegrille.net.