diff --git a/mod/hotpot/restorelib.php b/mod/hotpot/restorelib.php
index 20faec8b6d1..500648ad77a 100644
--- a/mod/hotpot/restorelib.php
+++ b/mod/hotpot/restorelib.php
@@ -283,6 +283,15 @@ function hotpot_restore_record(&$restore, $status, &$xml, $table, $foreign_keys,
     //    the name of the secondary key field, if any, in the current $record.
     //    If this field is specified, then the current record will only be added
     //    if the $record->$secondarykey value does not already exist in $table
+
+    // maintain a cache of info on table columns
+    static $table_columns = array();
+    if (empty($table_columns[$table])) {
+        global $CFG, $db;
+        $table_columns[$table] = $db->MetaColumns("$CFG->prefix$table");
+    }
+
+    // get values for fields in this record
     unset($record);
     $TAGS = array_keys($xml);
     foreach ($TAGS as $TAG) {
@@ -292,39 +301,63 @@ function hotpot_restore_record(&$restore, $status, &$xml, $table, $foreign_keys,
             $record->$tag = backup_todb($value);
         }
     }
+
+    // update secondary keys, if any
     $ok = true;
     foreach ($foreign_keys as $key=>$value) {
         if (is_numeric($value)) {
             $record->$key = $value;
         } else {
-            if (empty($record->$key)) {
-                $record->$key = NULL;
-            } else {
-                $key_table = $value;
-                $new_ids = array();
+            $key_table = $value;
+            $new_ids = array();
+            if (isset($record->$key)) {
                 $old_ids = explode(',', $record->$key);
                 foreach ($old_ids as $old_id) {
-                    $key_record = backup_getid($restore->backup_unique_code, $key_table, $old_id);
-                    if ($key_record) {
-                        $new_ids[] = $key_record->new_id;
+                    if (empty($old_id)) {
+                        // do nothing
                     } else {
-                        // foreign key could not be updated
-                        if (!defined('RESTORE_SILENTLY')) {
-                            print "<ul><li><b>Warning:</b><br>Foreign key could not be updated:<br>";
-                            print "'$key_table' record (old id=$old_id) is missing from backup data<br>";
-                            print "'$table' record ";
-                            if (isset($record->id)) {
-                                print "(old id=$record->id) ";
+                        $key_record = backup_getid($restore->backup_unique_code, $key_table, $old_id);
+                        if ($key_record) {
+                            $new_ids[] = $key_record->new_id;
+                        } else {
+                            // foreign key could not be updated
+                            if (!defined('RESTORE_SILENTLY')) {
+                                print "<ul><li><b>Warning:</b><br>Foreign key could not be updated:<br>";
+                                print "'$key_table' record (old id=$old_id) is missing from backup data<br>";
+                                print "'$table' record ";
+                                if (isset($record->id)) {
+                                    print "(old id=$record->id) ";
+                                }
+                                print "was not restored</li></ul>";
                             }
-                            print "was not restored</li></ul>";
+                            $ok = false; 
                         }
-                        $ok = false; 
                     }
                 }
-                $record->$key = implode(',', $new_ids);
+            }
+            $record->$key = implode(',', $new_ids);
+        }
+    }
+
+    // check all "not null" fields have been set
+    foreach ($table_columns[$table] as $column) {
+        if ($column->not_null) {
+            $name = $column->name;
+            if ($name<>'id' && empty($record->$name)) {
+                if (isset($column->default_value)) {
+                    $default = $column->default_value;
+                } else {
+                    if (preg_match('/int|decimal|double|float|time|year/i', $column->type)) {
+                        $default = 0;
+                    } else {
+                        $default = '';
+                    }
+                }
+                $record->$name = $default;
             }
         }
     }
+
     // check everything is OK so far
     if ($ok && isset($record)) {
         // store old record id, if necessary
@@ -343,7 +376,7 @@ function hotpot_restore_record(&$restore, $status, &$xml, $table, $foreign_keys,
         }
         if (empty($record->id)) {
             // add the $record (and get new id)
-            $record->id = insert_record ($table, $record);
+            $record->id = insert_record($table, $record);
         }
         // check $record was added (or found)
         if (is_numeric($record->id)) {