do_shortcode() in an AJAX call

do_shortcode AJAX

function add_twitter_discount() {
	global $post;
	
	$post_id = $_POST['id'];
	
	$item = get_post_meta( $post_id, 'item_number_discount', true );
	$numb = str_replace( 'theme-', '', $item );
	
	//if ( 'POST' == $_SERVER['REQUEST_METHOD'] && !empty( $_POST['action'] ) && $_POST['action'] == 'confirmed' ) {
		$arr = array();
		$entry['code'] = "success";
		$entry['id']   = $post_id;
		$entry['link'] = '<a class="purchase discount" href="javascript:{}" onclick="document.getElementById(\'cartButtonForm_'. $numb .'\').submit(); return false;">Purchase discount</a>';
		ob_start();
			echo do_shortcode("[add_to_cart item='".$item."' showprice='no' ]");
		$entry['form'] = ob_get_contents();
		ob_get_clean();
		
		$arr[] = $entry;
		header("Content-Type: application/json");
		echo json_encode($arr);
		exit();
	//}
}
add_action( 'wp_ajax_add_discount', 'add_twitter_discount' ); //hook to ajax action
add_action( 'wp_ajax_nopriv_add_discount', 'add_twitter_discount' ); //hook to ajax action

Related: I adding in the ob_* stuff today trying it out. I had it as $entry['form'] = do_shortcode("[add_to_cart item='".$item."' showprice='no' ]"); which was working last time I checked (which was pre WP 3.1)...

The ob_start and ob_get_clean seem suspect. Dunno why, but how about just $x = do_shortcode(); then cast $x into you $entry['form']; ?

Tried that, but it's not working. Ended up calling the shortcode function directly and avoiding do_shortcode which stopped working in this manner..