Set FB OG image (Wordpress)

function insert_image_src_rel_in_head() { global $post; if ( !is_singular()) //if it is not a post or a page return; if(!has_post_thumbnail( $post->ID )) { //the post does not have featured image, use a default image $default_image="http://example.com/image.jpg"; //replace this with a default image on your server or an image in your media library echo '<meta property="og:image" content="' . $default_image . '"/>'; } else{ $thumbnail_src = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'medium' ); echo '<meta property="og:image" content="' . esc_attr( $thumbnail_src[0] ) . '"/>'; } echo " "; } add_action( 'wp_head', 'insert_image_src_rel_in_head', 5 );