Adiciona informações do facebook a campos personalizados WordPress

insert-likes-custom-field.php

<?php
/**
* Author: Rhuan Carlos 
*/
function insert_likes_custom_field( $post_ID ) {
    global $wpdb;

    if ( !wp_is_post_revision( $post_ID ) ){
        add_post_meta( $post_ID, 'likes_count', '0', true );
    }
}
add_action( 'publish_page', 'insert_likes_custom_field' );
add_action( 'publish_post', 'insert_likes_custom_field' );

/**
 * Extrai número de likes do artigo
 *
 */
function update_facebook_likes( $content = '' ) {
    global $wp_query;

    $post_ID = $wp_query->post->ID;
    $data = file_get_contents( 'http://graph.facebook.com/?id='. get_permalink() );
    if( $data !== false ){
        $json = json_decode( $data );
        $likes = $json->{'comments'};

        $meta_values = get_post_meta( $post_ID, 'likes_count', true );

        if ( empty( $likes ) ) {
            $likes = '0';
        }

        if( $meta_values > $likes ){
            update_post_meta( $post_ID, 'likes_count', $likes, false);
        }
    }

    return $content;
}
add_action( 'the_content', 'update_facebook_likes' );