可捕获的致命错误：传递给Facebook \ FacebookRequest :: __ construct（）的参数1必须是Facebook \ FacebookSession的实例，

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可捕获的致命错误：传递给Facebook \ FacebookRequest :: __ construct（）的参数1必须是Facebook \ FacebookSession的实例，是给定的__PHP_Incomplete_Class的实例，在第67行的C：\ xampp \ htdocs \ FB \ download_album.php中调用并在第182行“ strong text”中的C：\ xampp \ htdocs \ FB \ libs \ Facebook \ FacebookRequest.php中定义

if ( isset( $_GET['all_albums'] ) && !empty ( $_GET['all_albums'] ) ) {
    if ( $_GET['all_albums'] == 'all_albums' ) {

        require_once('libs/Facebook/FacebookSession.php');
        // graph api request for user data
        $request_albums = new FacebookRequest($session, 'GET', '/me/albums?fields=id,name');
        $response_albums = $request_albums->execute();

        // get response
        $albums = $response_albums->getGraphObject()->asArray();

        if ( !empty( $albums ) ) {
            foreach ( $albums['data'] as $album ) {
                $album = (array) $album;
                download_album( $session, $album_download_directory, $album['id'], $album['name'] );
            }
        }
    } 
}