MDL-64205 privacy: Delete orphaned data request records on upgrade

As a result of the bug, some requests can be orphaned - the linked user
record may not exist any more. This is a cleanup of such records.

admin/tool/dataprivacy/db/upgrade.php

@@ -215,5 +215,19 @@ function xmldb_tool_dataprivacy_upgrade($oldversion) {
         upgrade_plugin_savepoint(true, 2017051554, 'tool', 'dataprivacy');
     }
 
+    if ($oldversion < 2017051556) {
+        // Delete orphaned data privacy requests.
+        $sql = "SELECT r.id
+                  FROM {tool_dataprivacy_request} r LEFT JOIN {user} u ON r.userid = u.id
+                 WHERE u.id IS NULL";
+        $orphaned = $DB->get_fieldset_sql($sql);
+
+        if ($orphaned) {
+            $DB->delete_records_list('tool_dataprivacy_request', 'id', $orphaned);
+        }
+
+        upgrade_plugin_savepoint(true, 2017051556, 'tool', 'dataprivacy');
+    }
+
     return true;
 }

admin/tool/dataprivacy/version.php

@@ -24,6 +24,6 @@
 
 defined('MOODLE_INTERNAL') || die;
 
-$plugin->version   = 2017051555;
+$plugin->version   = 2017051556;
 $plugin->requires  = 2017051507.00;        // Moodle 3.3.7 (Build: 20180517) and upwards.
 $plugin->component = 'tool_dataprivacy';