question/classes/question_reference_manager.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 namespace core_question;
  18
  19 use core_question\local\bank\question_version_status;
  20
  21 /**
  22  * This class should provide an API for managing question_references.
  23  *
  24  * Unfortunately, question_references were introduced in the DB structure
  25  * without an nice API. This class is being added later, and is currently
  26  * terribly incomplete, but hopefully it can be improved in time.
  27  *
  28  * @package    core_question
  29  * @copyright  2023 The Open University
  30  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  31  */
  32 class question_reference_manager {
  33     /**
  34      * Return a list of those questions from the list passed in, which are referenced.
  35      *
  36      * A question is referenced if either:
  37      * - There is a question_reference pointing at exactly that version of that question; or
  38      * - There is an 'always latest' reference, and the question id is the latest non-draft version
  39      *   of that question_bank_entry.
  40      *
  41      * @param array $questionids a list of question ids to check.
  42      * @return array a list of the question ids from the input array which are referenced.
  43      */
  44     public static function questions_with_references(array $questionids): array {
  45         global $DB;
  46
  47         if (empty($questionids)) {
  48             return [];
  49         }
  50
  51         [$qidtest, $params] = $DB->get_in_or_equal($questionids, SQL_PARAMS_NAMED, 'outerqid');
  52         [$lqidtest, $lparams] = $DB->get_in_or_equal($questionids, SQL_PARAMS_NAMED, 'innerqid');
  53
  54         return $DB->get_fieldset_sql("
  55             SELECT qv.questionid
  56
  57               FROM {question_versions} qv
  58
  59          -- This is a performant to get the latest non-draft version for each
  60          -- question_bank_entry that relates to one of our questionids.
  61          LEFT JOIN (
  62                        SELECT lqv.questionbankentryid,
  63                               MAX(lv.version) AS latestusableversion
  64                          FROM {question_versions} lqv
  65                          JOIN {question_versions} lv ON lv.questionbankentryid = lqv.questionbankentryid
  66                         WHERE lqv.questionid $lqidtest
  67                           AND lv.status <> :draft
  68                      GROUP BY lqv.questionbankentryid
  69                    ) latestversions ON latestversions.questionbankentryid = qv.questionbankentryid
  70
  71               JOIN {question_references} qr ON qr.questionbankentryid = qv.questionbankentryid
  72                        AND (qr.version = qv.version OR qr.version IS NULL AND qv.version = latestversions.latestusableversion)
  73
  74              WHERE qv.questionid $qidtest
  75             ", array_merge($params, $lparams, ['draft' => question_version_status::QUESTION_STATUS_DRAFT]));
  76     }
  77 }