From e716c18fb94b718c1b7c70b723ebe6b53478e2b7 Mon Sep 17 00:00:00 2001
From: "Eloy Lafuente (stronk7)" <stronk7@moodle.org>
Date: Wed, 25 Nov 2015 00:19:30 +0100
Subject: [PATCH] MDL-52291 questions: fix upgrade from 2.5 and earlier

Because of some changes performed to the multichoice qtype
for Moodle 2.6, older sites are not able to upgrade properly.

This commits does introduce DB introspection to decide which
table and column names must be used. Nasty but enough.

Note MDL-52298 has been created about to avoid/minimize the
chances of this happening again.
---
 question/type/multianswer/db/upgrade.php | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/question/type/multianswer/db/upgrade.php b/question/type/multianswer/db/upgrade.php
index 0cd685c79cc..dbf181eefa6 100644
--- a/question/type/multianswer/db/upgrade.php
+++ b/question/type/multianswer/db/upgrade.php
@@ -61,6 +61,15 @@ function xmldb_qtype_multianswer_upgrade($oldversion) {
     // Put any upgrade step following this.
 
     if ($oldversion < 2015100201) {
+        // Detect the exact table/field we want to use, coz can be different
+        // depending of the version we are upgrading from. See MDL-52291 and MDL-52298.
+        $multichoicetable = 'qtype_multichoice_options';
+        $multichoicefield = 'questionid';
+        if (!$dbman->table_exists($multichoicetable)) {
+            // Multichoice not upgraded yet, let's use old names.
+            $multichoicetable = 'question_multichoice';
+            $multichoicefield = 'question';
+        }
         $rs = $DB->get_recordset_sql("SELECT q.id, q.category, qma.sequence
                  FROM {question} q
                  JOIN {question_multianswer} qma ON q.id = qma.question");
@@ -71,21 +80,21 @@ function xmldb_qtype_multianswer_upgrade($oldversion) {
                 $wrappedquestions = $DB->get_records_list('question', 'id', $sequence, 'id ASC');
                 foreach ($wrappedquestions as $wrapped) {
                     if ($wrapped->qtype == 'multichoice') {
-                        $options = $DB->get_record('qtype_multichoice_options', array('questionid' => $wrapped->id), '*');
+                        $options = $DB->get_record($multichoicetable, array($multichoicefield => $wrapped->id), '*');
                         if (isset($options->shuffleanswers)) {
                             preg_match('/'.ANSWER_REGEX.'/s', $wrapped->questiontext, $answerregs);
                             if (isset($answerregs[ANSWER_REGEX_ANSWER_TYPE_MULTICHOICE]) &&
                                     $answerregs[ANSWER_REGEX_ANSWER_TYPE_MULTICHOICE] !== '') {
-                                $DB->set_field('qtype_multichoice_options', 'shuffleanswers', '0',
+                                $DB->set_field($multichoicetable, 'shuffleanswers', '0',
                                         array('id' => $options->id) );
                             }
                         } else {
                             $newrecord = new stdClass();
-                            $newrecord->questionid = $wrapped->id;
+                            $newrecord->$multichoicefield = $wrapped->id;
                             $newrecord->correctfeedback = '';
                             $newrecord->partiallycorrectfeedback = '';
                             $newrecord->incorrectfeedback = '';
-                            $DB->insert_record('qtype_multichoice_options', $newrecord);
+                            $DB->insert_record($multichoicetable, $newrecord);
                         }
                     }
                 }