* Performs a search operation with the provided form data.
     *
     * @param form the list form containing search criteria
     * @return HTML response with search results
     */
    protected HtmlResponse doSearch(final ListForm form) {
        validate(form, messages -> {}, this::asListHtml);

        if (StringUtil.isBlank(form.q)) {
            // query matches on all documents.

                if (session != null && form.num != null) {
                    session.setAttribute(Constants.RESULTS_PER_PAGE, form.num);
                }
            });
        }
        return doSearch(form);
    }

    /**
     * The previous page.
     * @param form The search form.
     * @return The HTML response.
     */
    @Execute
    public HtmlResponse prev(final SearchForm form) {