[Html-widget] Set error message in callback

[Yves Räber]

Hello, 

I need to set the error message within a callback function.

Something like this (using Catalyst framework) :

    $w->constraint('Callback', 'phone')->callback(
        sub { 
        	my $number = shift;
        	my $res = $c->forward('/get_prefix',[$number]);
		# I'd like to set the error message here
		$error_msg = $c->stahs->{prefix_info};
        	return ($number) ? $res : 1;        	
        } );

I've no idea how I can set the message within the callback function.
Does anyone has a working example ? I've searched everywhere : forums,
mailing list and google of course.

Yves.