Write validation helpers 

hook 'after_template_render' => sub {
    my($html) = @_;

    if(my $values = $global{fill_in_values}) {
        my %opt = %{ $global{fill_in_opt} };
        $opt{invalid_class}           //= "validation-error";
        $opt{fill_password}           //= 0;
        $opt{clear_absent_checkboxes} //= 1;
        if( $global{invalid_fields} ) {
            $opt{invalid_fields} = $global{invalid_fields};
        }
        my $output = HTML::FillInForm->fill( $html, $values, %opt );
        $$html = $output;
    }
};