carlodaniele

<?php
/**
 * Add meta box
 *
 * @param post $post The post object
 * @link https://codex.wordpress.org/Plugin_API/Action_Reference/add_meta_boxes
 */
function food_add_meta_boxes( $post ){
	add_meta_box( 'food_meta_box', __( 'Nutrition facts', 'food_example_plugin' ), 'food_build_meta_box', 'food', 'side', 'low' );
}

carlodaniele

<?php
/**
 * Build custom field meta box
 *
 * @param post $post The post object
 */
function food_build_meta_box( $post ){
	// our code here
}

carlodaniele

<?php
wp_nonce_field( basename( __FILE__ ), 'food_meta_box_nonce' );

carlodaniele

<?php
// retrieve the _food_cholesterol current value
$current_cholesterol = get_post_meta( $post->ID, '_food_cholesterol', true );

// retrieve the _food_carbohydrates current value
$current_carbohydrates = get_post_meta( $post->ID, '_food_carbohydrates', true );

// stores _food_vitamins array
$current_vitamins = ( get_post_meta( $post->ID, '_food_vitamins', true ) ) ? get_post_meta( $post->ID, '_food_vitamins', true ) : array();

carlodaniele

?>
<div class='inside'>
	<h3><?php _e( 'Carbohydrates', 'food_example_plugin' ); ?></h3>
	<p>
		<input type="text" name="carbohydrates" value="<?php echo $current_carbohydrates; ?>" /> 
	</p>
</div>
<?php

carlodaniele

<h3><?php _e( 'Cholesterol', 'food_example_plugin' ); ?></h3>
<p>
	<input type="radio" name="cholesterol" value="0" <?php checked( $current_cholesterol, '0' ); ?> /> Yes<br />
	<input type="radio" name="cholesterol" value="1" <?php checked( $current_cholesterol, '1' ); ?> /> No
</p>

carlodaniele

<h3><?php _e( 'Vitamins', 'food_example_plugin' ); ?></h3>
<p>
	<input type="checkbox" name="vitamins[]" value="Vitamin A" <?php checked( ( in_array( 'Vitamin A', $current_vitamins ) ) ? 'Vitamin A' : '', 'Vitamin A' ); ?> />Vitamin A <br />
	<input type="checkbox" name="vitamins[]" value="Thiamin (B1)" <?php checked( ( in_array( 'Thiamin (B1)', $current_vitamins ) ) ? 'Thiamin (B1)' : '', 'Thiamin (B1)' ); ?> />Thiamin (B1) <br />

	<!-- more vitamins here -->
</p>

carlodaniele

<?php
( in_array( 'Thiamin (B1)', $current_vitamins ) ) ? 'Thiamin (B1)' : ''

carlodaniele

<?php
// an array of values
$vitamins = array( 'Vitamin A', 'Thiamin (B1)', 'Riboflavin (B2)', 'Niacin (B3)', 'Pantothenic Acid (B5)', 'Vitamin B6', 'Vitamin B12', 'Vitamin C', 'Vitamin D', 'Vitamin E', 'Vitamin K' );

// stores _food_vitamins array 
$current_vitamins = ( get_post_meta( $post->ID, '_food_vitamins', true ) ) ? get_post_meta( $post->ID, '_food_vitamins', true ) : array();
?>
<div class='inside'>
	<h3><?php _e( 'Vitamins', 'food_example_plugin' ); ?></h3>
	<p>

carlodaniele

<?php
/**
 * Build custom field meta box
 *
 * @param post $post The post object
 */
function food_build_meta_box( $post ){
	// make sure the form request comes from WordPress
	wp_nonce_field( basename( __FILE__ ), 'food_meta_box_nonce' );