Custom shortcode with required field Contact Form 7

Hey guys,

This is my first post and I’m a bit of a newbie but hope you guys can help. I’ve searched the forum and googled but I can’t seem to find an answer.

I basically added a hook to my functions.php file to support a custom shortcode for Contact Form 7 (which is awesome btw) to go pull posts for a specific category. I got it working but whenever I use the * character to indicate if a field is required it doesn’t work.

Note: I got the code from this http://wordpress.org/support/topic/how-to-add-new-custom-shortcode Post and code by Wzshop.

Code:

add_action( 'wpcf7_init', 'custom_add_shortcode_dropdown' );
function custom_add_shortcode_dropdown() {
    wpcf7_add_shortcode( array( 'postdropdown', 'postdropdown*'), 'custom_dropdown_shortcode_handler', true);
}

function custom_dropdown_shortcode_handler(){
global $post;
$args = array('category_name' => 'activite-a-venir');
$myposts = get_posts( $args );
$output = "<select name='formation'><option value=\"\">---</option>";
foreach ( $myposts as $post ) : setup_postdata($post);
	$title = get_the_title();
	$output .= "<option value='$title'> $title </option>";

	endforeach;
$output .= "</select>";
return $output;
}

https://wordpress.org/plugins/contact-form-7/