Example
/**
* Add meta box to post types.
*
* @since 1.0.0
*/
function myplugin_add_meta_box() {
// Set up the default post types/
$types = array(
'post',
);
// Optional filter for adding the meta box to more types. Uncomment to use.
// $types = apply_filters( 'myplugin_meta_box_types', $types );
// Add the meta box to the page
add_meta_box(
'myplugin-meta-box', // Meta Box Id. Can be anything.
_x( 'Custom Meta', 'Custom Meta Box', 'myplugin' ), // The title of the meta box. Translation is optional. Can just be string.
'myplugin_render_meta_box', // The render meta box function.
$types, // Add the post types to which to add the meta box.
'side', // Show on the side of edit.
'high' // Show at top of edit.
);
}
add_action( 'add_meta_boxes', 'myplugin_add_meta_box' );
/**
* Render the meta box.
*
* This shows examples of a basic input and a select inside a meta box. These can be anything.
*
* @since 1.0.0
*
* @param $post WP_Post The post being edited.
*/
function myplugin_render_meta_box( $post ) {
// Get the current post meta values for our custom meta box.
$city = get_post_meta( $post->ID, 'city', true ); // True is for returning a single value.
$country = get_post_meta( $post->ID, 'country', true ); // True is for returning a single value.
// Add the WP Nonce field for security.
wp_nonce_field( plugin_basename( __FILE__ ), 'myplugin_meta_nonce' );
?>
<p>
<label for="city">
<?php _ex( 'City', 'Custom Meta Box Template', 'myplugin' ); ?>
</label>
<input name="city" id="city" value="<?php echo $city; ?>" />
</p>
<p>
<label for="country">
<?php _ex( 'Country', 'Custom Meta Box Template', 'myplugin' ); ?>
</label>
<select name="country" id="country">
<option value="United States" <?php selected( $country, 'United States' ); ?>><?php _ex( 'United States', 'Custom Meta Box Template', 'myplugin' ); ?></option>
<option value="Mexico" <?php selected( $country, 'Mexico' ); ?>><?php _ex( 'Mexico', 'Custom Meta Box Template', 'myplugin' ); ?></option>
<option value="Canada" <?php selected( $country, 'Canada' ); ?>><?php _ex( 'Canada', 'Custom Meta Box Template', 'myplugin' ); ?></option>
</select>
</p>
<?php
}
/**
* Save meta box data.
*
* @since 1.0.0
*
* @param $post_id int The Id of the Post being saved.
*/
function myplugin_save_meta_data( $post_id ) {
// Verify this is not an auto save.
if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
return;
}
// Validate the meta box nonce for security.
if ( ! isset( $_POST['myplugin_meta_nonce'] ) || ! wp_verify_nonce( $_POST['myplugin_meta_nonce'], plugin_basename( __FILE__ ) ) ) {
return;
}
// Get the new values from the form.
$city = $_POST['city'];
$country = $_POST['country'];
// update_post_meta will add the value if it doesn't exist or update it if it does.
update_post_meta( $post_id, 'city', $city );
update_post_meta( $post_id, 'country', $country );
/*
* OPTIONAL ALTERNATIVE
*
* Instead of just using update_post_meta, you could also check the values and
* issue create/update/delete on the post meta value.
*/
// $current_city_value = get_post_meta( $post_id, 'city', true ); // True is for returning a single value.
//
// // Add the post meta if it doesn't exist.
// if ( $city && '' === $city ) {
// add_post_meta( $post_id, 'city', $city, true ); // True means the key is unique to the post. False is default and more than one can be added.
// }
// // Edit the post meta if it does exist and there is a new value.
// elseif ( $city && $city != $current_city_value ) {
// update_post_meta( $post_id, 'city', $city );
// }
// // Delete the post meta if there is no new value.
// elseif ( '' === $city && $current_city_value ) {
// delete_post_meta( $post_id, 'city', $current_city_value ); // $current_city_value is optional and is used to differentiate between other values with the same key.
// }
}
add_action( 'save_post', 'myplugin_save_meta_data' );
