commit a9b09b7a0e244734c92dbd0fc245a3851273434b
Author: Francis Devine <francis@xeon.pw>
Date:   Tue Sep 3 23:58:31 2013 +1200

    adds duplicate idname and duplicate shortname checks to update_course, also adds duplicate idname validation to the course edit form

diff --git a/course/edit_form.php b/course/edit_form.php
index c845331..d4be40e 100644
--- a/course/edit_form.php
+++ b/course/edit_form.php
@@ -329,6 +329,7 @@ class course_edit_form extends moodleform {
         global $DB, $CFG;
 
         $errors = parent::validation($data, $files);
+        //check we don't have a duplicate shortname
         if ($foundcourses = $DB->get_records('course', array('shortname'=>$data['shortname']))) {
             if (!empty($data['id'])) {
                 unset($foundcourses[$data['id']]);
@@ -342,6 +343,18 @@ class course_edit_form extends moodleform {
             }
         }
 
+        //check we don't have a duplicate idnumber
+        if (!empty($data['idnumber'])) {
+            $foundcourses = $DB->get_records('course', array('idnumber'=>$data['idnumber']));
+            if (!empty($data['id'])) {
+                unset($foundcourses[$data['id']]);
+            }   
+            if (!empty($foundcourses)) {
+                $errors['idnumber']= get_string('idnumbertaken');
+            }   
+        }   
+
+
         $errors = array_merge($errors, enrol_course_edit_validation($data, $this->context));
 
         $courseformat = course_get_format((object)array('format' => $data['format']));
diff --git a/course/lib.php b/course/lib.php
index 6ed5bb5..6561d73 100644
--- a/course/lib.php
+++ b/course/lib.php
@@ -2361,6 +2361,20 @@ function update_course($data, $editoroptions = NULL) {
     if ($overviewfilesoptions = course_overviewfiles_options($data->id)) {
         $data = file_postupdate_standard_filemanager($data, 'overviewfiles', $overviewfilesoptions, $context, 'course', 'overviewfiles', 0);
     }
+    
+    //check we don't have a duplicate shortname
+    if(!empty($data->shortname) and $oldcourse->shortname!= $data->shortname) {
+        if ($DB->record_exists('course', array('idnumber', => $data->shortname))) {
+            throw new moodle_exception('shortnametaken');
+        }
+    }
+
+    //check we don't have a duplicate idnumber
+    if (!empty($data->idnumber) and $oldcourse->idnumber != $data->idnumber) {
+        if ($DB->record_exists('course', array('idnumber' => $data->idnumber))) {
+            throw new moodle_exception('idnumbertaken');
+        }    
+    }    
 
     if (!isset($data->category) or empty($data->category)) {
         // prevent nulls and 0 in category field