MDL-78025 questions: questions_in_use should check question_references

This avoids the needs for plugins to do separate queries, which is easier for them, and better performing.
2023-04-26 15:29:38 +01:00
parent 9775be13e9
commit 25596a50e5
3 changed files with 205 additions and 0 deletions
@@ -0,0 +1,77 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace core_question;
+
+use core_question\local\bank\question_version_status;
+
+/**
+ * This class should provide an API for managing question_references.
+ *
+ * Unfortunately, question_references were introduced in the DB structure
+ * without an nice API. This class is being added later, and is currently
+ * terribly incomplete, but hopefully it can be improved in time.
+ *
+ * @package    core_question
+ * @copyright  2023 The Open University
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class question_reference_manager {
+    /**
+     * Return a list of those questions from the list passed in, which are referenced.
+     *
+     * A question is referenced if either:
+     * - There is a question_reference pointing at exactly that version of that question; or
+     * - There is an 'always latest' reference, and the question id is the latest non-draft version
+     *   of that question_bank_entry.
+     *
+     * @param array $questionids a list of question ids to check.
+     * @return array a list of the question ids from the input array which are referenced.
+     */
+    public static function questions_with_references(array $questionids): array {
+        global $DB;
+
+        if (empty($questionids)) {
+            return [];
+        }
+
+        [$qidtest, $params] = $DB->get_in_or_equal($questionids, SQL_PARAMS_NAMED, 'outerqid');
+        [$lqidtest, $lparams] = $DB->get_in_or_equal($questionids, SQL_PARAMS_NAMED, 'innerqid');
+
+        return $DB->get_fieldset_sql("
+            SELECT qv.questionid
+
+              FROM {question_versions} qv
+
+         -- This is a performant to get the latest non-draft version for each
+         -- question_bank_entry that relates to one of our questionids.
+         LEFT JOIN (
+                       SELECT lqv.questionbankentryid,
+                              MAX(lv.version) AS latestusableversion
+                         FROM {question_versions} lqv
+                         JOIN {question_versions} lv ON lv.questionbankentryid = lqv.questionbankentryid
+                        WHERE lqv.questionid $lqidtest
+                          AND lv.status <> :draft
+                     GROUP BY lqv.questionbankentryid
+                   ) latestversions ON latestversions.questionbankentryid = qv.questionbankentryid
+
+              JOIN {question_references} qr ON qr.questionbankentryid = qv.questionbankentryid
+                       AND (qr.version = qv.version OR qr.version IS NULL AND qv.version = latestversions.latestusableversion)
+
+             WHERE qv.questionid $qidtest
+            ", array_merge($params, $lparams, ['draft' => question_version_status::QUESTION_STATUS_DRAFT]));
+    }
+}