my $data = get_data_from('foo');

die('no data') unless(defined($data));
 
my $obj = decode_json($data);

if(defined($obj)){
    if(exists($obj->{'foo'}) && defined($obj->{'foo'})){
        if (exists($obj->{'foo'}->{'bar'}) && defined($obj->{'foo'}->{'bar'})){
             print $obj->{'foo'}->{'bar'};
        }
    }
}