diff --git a/course/completion.php b/course/completion.php
index e6ffef893e9..6f3ccd540ff 100644
--- a/course/completion.php
+++ b/course/completion.php
@@ -103,44 +103,43 @@ if ($form->is_cancelled()){
 
     // Handle aggregation methods
     // Overall aggregation
-    $aggregation = new completion_aggregation();
-    $aggregation->course = $data->id;
-    $aggregation->criteriatype = null;
+    $aggdata = array(
+        'course'        => $data->id,
+        'criteriatype'  => null
+    );
+    $aggregation = new completion_aggregation($aggdata);
     $aggregation->setMethod($data->overall_aggregation);
-    $aggregation->insert();
+    $aggregation->save();
 
     // Activity aggregation
     if (empty($data->activity_aggregation)) {
         $data->activity_aggregation = 0;
     }
 
-    $aggregation = new completion_aggregation();
-    $aggregation->course = $data->id;
-    $aggregation->criteriatype = COMPLETION_CRITERIA_TYPE_ACTIVITY;
+    $aggdata['criteriatype'] = COMPLETION_CRITERIA_TYPE_ACTIVITY;
+    $aggregation = new completion_aggregation($aggdata);
     $aggregation->setMethod($data->activity_aggregation);
-    $aggregation->insert();
+    $aggregation->save();
 
     // Course aggregation
     if (empty($data->course_aggregation)) {
         $data->course_aggregation = 0;
     }
 
-    $aggregation = new completion_aggregation();
-    $aggregation->course = $data->id;
-    $aggregation->criteriatype = COMPLETION_CRITERIA_TYPE_COURSE;
+    $aggdata['criteriatype'] = COMPLETION_CRITERIA_TYPE_COURSE;
+    $aggregation = new completion_aggregation($aggdata);
     $aggregation->setMethod($data->course_aggregation);
-    $aggregation->insert();
+    $aggregation->save();
 
     // Role aggregation
     if (empty($data->role_aggregation)) {
         $data->role_aggregation = 0;
     }
 
-    $aggregation = new completion_aggregation();
-    $aggregation->course = $data->id;
-    $aggregation->criteriatype = COMPLETION_CRITERIA_TYPE_ROLE;
+    $aggdata['criteriatype'] = COMPLETION_CRITERIA_TYPE_ROLE;
+    $aggregation = new completion_aggregation($aggdata);
     $aggregation->setMethod($data->role_aggregation);
-    $aggregation->insert();
+    $aggregation->save();
 
     // Update course total passing grade
     if (!empty($data->criteria_grade)) {
@@ -152,7 +151,10 @@ if ($form->is_cancelled()){
         }
     }
 
-    redirect($CFG->wwwroot."/course/view.php?id=$course->id", get_string('changessaved'));
+    add_to_log($course->id, 'course', 'completion updated', 'completion.php?id='.$course->id);
+
+    $url = new moodle_url('/course/view.php', array('id' => $course->id));
+    redirect($url);
 }
 
 
diff --git a/lib/completion/completion_aggregation.php b/lib/completion/completion_aggregation.php
index 5591261f297..e6e626a4de9 100644
--- a/lib/completion/completion_aggregation.php
+++ b/lib/completion/completion_aggregation.php
@@ -1,5 +1,4 @@
 <?php
-
 // This file is part of Moodle - http://moodle.org/
 //
 // Moodle is free software: you can redistribute it and/or modify
@@ -19,65 +18,58 @@
 /**
  * Course completion critieria aggregation
  *
- * @package   moodlecore
+ * @package core_completion
+ * @category completion
  * @copyright 2009 Catalyst IT Ltd
- * @author    Aaron Barnes <aaronb@catalyst.net.nz>
- * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @author Aaron Barnes <aaronb@catalyst.net.nz>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
+
+defined('MOODLE_INTERNAL') || die();
 require_once($CFG->libdir.'/completion/data_object.php');
 
 /**
  * Course completion critieria aggregation
+ *
+ * @package core_completion
+ * @category completion
+ * @copyright 2009 Catalyst IT Ltd
+ * @author Aaron Barnes <aaronb@catalyst.net.nz>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class completion_aggregation extends data_object {
 
-    /**
-     * DB Table
-     * @var string $table
-     */
+    /* @var string Database table name that stores completion aggregation information */
     public $table = 'course_completion_aggr_methd';
 
     /**
      * Array of required table fields, must start with 'id'.
-     * @var array $required_fields
+     * Defaults to id, course, criteriatype, method, value
+     * @var array
      */
     public $required_fields = array('id', 'course', 'criteriatype', 'method', 'value');
 
-    /**
-     * Course id
-     * @access  public
-     * @var     int
-     */
+    /* @var array Array of unique fields, used in where clauses */
+    public $unique_fields = array('course', 'criteriatype');
+
+    /* @var int Course id */
     public $course;
 
-    /**
-     * Criteria type this aggregation method applies to, or NULL for overall course aggregation
-     * @access  public
-     * @var     int
-     */
+    /* @var int Criteria type this aggregation method applies to, or NULL for overall course aggregation */
     public $criteriatype;
 
-    /**
-     * Aggregation method (COMPLETION_AGGREGATION_* constant)
-     * @access  public
-     * @var     int
-     */
+    /* @var int Aggregation method (COMPLETION_AGGREGATION_* constant) */
     public $method;
 
-    /**
-     * Method value
-     * @access  public
-     * @var     mixed
-     */
+    /* @var mixed Method value */
     public $value;
 
 
     /**
      * Finds and returns a data_object instance based on params.
-     * @static abstract
      *
      * @param array $params associative arrays varname=>value
-     * @return object data_object instance or false if none found.
+     * @return data_object instance of data_object or false if none found.
      */
     public static function fetch($params) {
         return self::fetch_helper('course_completion_aggr_methd', __CLASS__, $params);
@@ -86,7 +78,6 @@ class completion_aggregation extends data_object {
 
     /**
      * Finds and returns all data_object instances based on params.
-     * @static abstract
      *
      * @param array $params associative arrays varname=>value
      * @return array array of data_object insatnces or false if none found.
@@ -95,9 +86,8 @@ class completion_aggregation extends data_object {
 
     /**
      * Set the aggregation method
-     * @access  public
-     * @param   $method     int
-     * @return  void
+     *
+     * @param int $method One of COMPLETION_AGGREGATION_ALL or COMPLETION_AGGREGATION_ANY
      */
     public function setMethod($method) {
         $methods = array(
@@ -111,4 +101,19 @@ class completion_aggregation extends data_object {
             $this->method = COMPLETION_AGGREGATION_ALL;
         }
     }
+
+
+    /**
+     * Save aggregation method to database
+     *
+     * @access  public
+     * @return  boolean
+     */
+    public function save() {
+        if ($this->id) {
+            return $this->update();
+        } else {
+            return $this->insert();
+        }
+    }
 }
diff --git a/lib/completion/completion_completion.php b/lib/completion/completion_completion.php
index 67377894116..e6523eadf26 100644
--- a/lib/completion/completion_completion.php
+++ b/lib/completion/completion_completion.php
@@ -1,5 +1,4 @@
 <?php
-
 // This file is part of Moodle - http://moodle.org/
 //
 // Moodle is free software: you can redistribute it and/or modify
@@ -15,103 +14,70 @@
 // You should have received a copy of the GNU General Public License
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
+/**
+ * Course completion status for a particular user/course
+ *
+ * @package core_completion
+ * @category completion
+ * @copyright 2009 Catalyst IT Ltd
+ * @author Aaron Barnes <aaronb@catalyst.net.nz>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+require_once($CFG->libdir.'/completion/data_object.php');
 
 /**
  * Course completion status for a particular user/course
  *
- * @package   moodlecore
+ * @package core_completion
+ * @category completion
  * @copyright 2009 Catalyst IT Ltd
- * @author    Aaron Barnes <aaronb@catalyst.net.nz>
- * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
- */
-require_once($CFG->libdir.'/completion/data_object.php');
-
-
-/**
- * Course completion status for a particular user/course
+ * @author Aaron Barnes <aaronb@catalyst.net.nz>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class completion_completion extends data_object {
 
-    /**
-     * DB Table
-     * @var string $table
-     */
+    /* @var string $table Database table name that stores completion information */
     public $table = 'course_completions';
 
-    /**
-     * Array of required table fields, must start with 'id'.
-     * @var array $required_fields
-     */
+    /* @var array $required_fields Array of required table fields, must start with 'id'. */
     public $required_fields = array('id', 'userid', 'course', 'deleted', 'timenotified',
         'timeenrolled', 'timestarted', 'timecompleted', 'reaggregate');
 
-    /**
-     * User ID
-     * @access  public
-     * @var     int
-     */
+    /* @var int $userid User ID */
     public $userid;
 
-    /**
-     * Course ID
-     * @access  public
-     * @var     int
-     */
+    /* @var int $course Course ID */
     public $course;
 
-    /**
-     * Set to 1 if this record has been deleted
-     * @access  public
-     * @var     int
-     */
+    /* @var int $deleted set to 1 if this record has been deleted */
     public $deleted;
 
-    /**
-     * Timestamp the interested parties were notified
-     * of this user's completion
-     * @access  public
-     * @var     int
-     */
+    /* @var int Timestamp the interested parties were notified of this user's completion. */
     public $timenotified;
 
-    /**
-     * Time of course enrolment
-     * @see     completion_completion::mark_enrolled()
-     * @access  public
-     * @var     int
-     */
+    /* @var int Time of course enrolment {@link completion_completion::mark_enrolled()} */
     public $timeenrolled;
 
     /**
-     * Time the user started their course completion
-     * @see     completion_completion::mark_inprogress()
-     * @access  public
-     * @var     int
+     * Time the user started their course completion {@link completion_completion::mark_inprogress()}
+     * @var int
      */
     public $timestarted;
 
-    /**
-     * Timestamp of course completion
-     * @see     completion_completion::mark_complete()
-     * @access  public
-     * @var     int
-     */
+    /* @var int Timestamp of course completion {@link completion_completion::mark_complete()} */
     public $timecompleted;
 
-    /**
-     * Flag to trigger cron aggregation (timestamp)
-     * @access  public
-     * @var     int
-     */
+    /* @var int Flag to trigger cron aggregation (timestamp) */
     public $reaggregate;
 
 
     /**
      * Finds and returns a data_object instance based on params.
-     * @static abstract
      *
-     * @param array $params associative arrays varname=>value
-     * @return object data_object instance or false if none found.
+     * @param array $params associative arrays varname = >value
+     * @return data_object instance of data_object or false if none found.
      */
     public static function fetch($params) {
         $params['deleted'] = null;
@@ -120,8 +86,8 @@ class completion_completion extends data_object {
 
     /**
      * Return status of this completion
-     * @access  public
-     * @return  boolean
+     *
+     * @return bool
      */
     public function is_complete() {
         return (bool) $this->timecompleted;
@@ -132,9 +98,7 @@ class completion_completion extends data_object {
      *
      * If the user is already marked as started, no change will occur
      *
-     * @access  public
-     * @param   integer $timeenrolled Time enrolled (optional)
-     * @return  void
+     * @param integer $timeenrolled Time enrolled (optional)
      */
     public function mark_enrolled($timeenrolled = null) {
 
@@ -147,18 +111,15 @@ class completion_completion extends data_object {
             $this->timeenrolled = $timeenrolled;
         }
 
-        $this->_save();
+        return $this->_save();
     }
 
     /**
      * Mark this user as inprogress in this course
      *
-     * If the user is already marked as inprogress,
-     * the time will not be changed
+     * If the user is already marked as inprogress, the time will not be changed
      *
-     * @access  public
-     * @param   integer $timestarted Time started (optional)
-     * @return  void
+     * @param integer $timestarted Time started (optional)
      */
     public function mark_inprogress($timestarted = null) {
 
@@ -176,7 +137,7 @@ class completion_completion extends data_object {
             $this->timestarted = $timestarted;
         }
 
-        $this->_save();
+        return $this->_save();
     }
 
     /**
@@ -185,9 +146,8 @@ class completion_completion extends data_object {
      * This generally happens when the required completion criteria
      * in the course are complete.
      *
-     * @access  public
-     * @param   integer $timecomplete Time completed (optional)
-     * @return  void
+     * @param integer $timecomplete Time completed (optional)
+     * @return void
      */
     public function mark_complete($timecomplete = null) {
 
@@ -205,39 +165,36 @@ class completion_completion extends data_object {
         $this->timecompleted = $timecomplete;
 
         // Save record
-        $this->_save();
+        return $this->_save();
     }
 
     /**
      * Save course completion status
      *
      * This method creates a course_completions record if none exists
-     * @access  public
-     * @return  void
+     * @access  private
+     * @return  bool
      */
     private function _save() {
-
-        global $DB;
-
         if ($this->timeenrolled === null) {
             $this->timeenrolled = 0;
         }
 
         // Save record
         if ($this->id) {
-            $this->update();
+            return $this->update();
         } else {
             // Make sure reaggregate field is not null
             if (!$this->reaggregate) {
                 $this->reaggregate = 0;
             }
 
-			// Make sure timestarted is not null
-			if (!$this->timestarted) {
-				$this->timestarted = 0;
-			}
-			
-            $this->insert();
+            // Make sure timestarted is not null
+            if (!$this->timestarted) {
+                $this->timestarted = 0;
+            }
+
+            return $this->insert();
         }
     }
 }
diff --git a/lib/completion/completion_criteria.php b/lib/completion/completion_criteria.php
index 293d318dd55..56a4360fc47 100644
--- a/lib/completion/completion_criteria.php
+++ b/lib/completion/completion_criteria.php
@@ -141,11 +141,11 @@ abstract class completion_criteria extends data_object {
     public static function factory($params) {
         global $CFG, $COMPLETION_CRITERIA_TYPES;
 
-        if (!isset($params->criteriatype) || !isset($COMPLETION_CRITERIA_TYPES[$params->criteriatype])) {
+        if (!isset($params['criteriatype']) || !isset($COMPLETION_CRITERIA_TYPES[$params['criteriatype']])) {
             error('invalidcriteriatype', 'completion');
         }
 
-        $class = 'completion_criteria_'.$COMPLETION_CRITERIA_TYPES[$params->criteriatype];
+        $class = 'completion_criteria_'.$COMPLETION_CRITERIA_TYPES[$params['criteriatype']];
         require_once($CFG->libdir.'/completion/'.$class.'.php');
 
         return new $class($params, false);
diff --git a/lib/completion/completion_criteria_activity.php b/lib/completion/completion_criteria_activity.php
index 096d1572256..23184361b92 100644
--- a/lib/completion/completion_criteria_activity.php
+++ b/lib/completion/completion_criteria_activity.php
@@ -229,8 +229,7 @@ class completion_criteria_activity extends completion_criteria {
         // Loop through completions, and mark as complete
         $rs = $DB->get_recordset_sql($sql);
         foreach ($rs as $record) {
-
-            $completion = new completion_criteria_completion((array)$record);
+            $completion = new completion_criteria_completion($record, DATA_OBJECT_FETCH_BY_KEY);
             $completion->mark_complete($record->timecompleted);
         }
         $rs->close();
diff --git a/lib/completion/completion_criteria_completion.php b/lib/completion/completion_criteria_completion.php
index 26127f8b128..7f448001d20 100644
--- a/lib/completion/completion_criteria_completion.php
+++ b/lib/completion/completion_criteria_completion.php
@@ -1,5 +1,4 @@
 <?php
-
 // This file is part of Moodle - http://moodle.org/
 //
 // Moodle is free software: you can redistribute it and/or modify
@@ -18,101 +17,68 @@
 /**
  * Completion data for a specific user, course and critieria
  *
- * @package   moodlecore
+ * @package core_completion
+ * @category completion
  * @copyright 2009 Catalyst IT Ltd
- * @author    Aaron Barnes <aaronb@catalyst.net.nz>
- * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @author Aaron Barnes <aaronb@catalyst.net.nz>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
-require_once($CFG->libdir.'/completion/data_object.php');
 
+defined('MOODLE_INTERNAL') || die();
+require_once($CFG->libdir.'/completion/data_object.php');
 
 /**
  * Completion data for a specific user, course and critieria
+ *
+ * @package core_completion
+ * @category completion
+ * @copyright 2009 Catalyst IT Ltd
+ * @author Aaron Barnes <aaronb@catalyst.net.nz>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class completion_criteria_completion extends data_object {
 
-    /**
-     * DB Table
-     * @var string $table
-     */
+    /* @var string Database table that stores completion type criteria */
     public $table = 'course_completion_crit_compl';
 
-    /**
-     * Array of required table fields, must start with 'id'.
-     * @var array $required_fields
-     */
+    /* @var array Array of required table fields, must start with 'id'. */
     public $required_fields = array('id', 'userid', 'course', 'criteriaid', 'gradefinal', 'rpl', 'deleted', 'unenroled', 'timecompleted');
 
-    /**
-     * User ID
-     * @access  public
-     * @var     int
-     */
+    /* @var array Array of unique fields, used in where clauses */
+    public $unique_fields = array('userid', 'course', 'criteriaid');
+
+    /* @var int User ID */
     public $userid;
 
-    /**
-     * Course ID
-     * @access  public
-     * @var     int
-     */
+    /* @var int course ID */
     public $course;
 
-    /**
-     * The id of the course completion criteria this completion references
-     * @access  public
-     * @var     int
-     */
+    /* @var int The id of the course completion criteria this completion references */
     public $criteriaid;
 
-    /**
-     * The final grade for the user in the course (if completing a grade criteria)
-     * @access  public
-     * @var     float
-     */
+    /* @var float The final grade for the user in the course (if completing a grade criteria) */
     public $gradefinal;
 
-    /**
-     * Record of prior learning, leave blank if none
-     * @access  public
-     * @var     string
-     */
+    /* @var string Record of prior learning, leave blank if none */
     public $rpl;
 
-    /**
-     * Course deleted flag
-     * @access  public
-     * @var     boolean
-     */
+    /* @var bool Course deleted flag */
     public $deleted;
 
-    /**
-     * Timestamp of user unenrolment (if completing a unenrol criteria)
-     * @access  public
-     * @var     int     (timestamp)
-     */
+    /* @var int Timestamp of user unenrolment (if completing a unenrol criteria) */
     public $unenroled;
 
-    /**
-     * Timestamp of course criteria completion
-     * @see     completion_criteria_completion::mark_complete()
-     * @access  public
-     * @var     int     (timestamp)
-     */
+    /* @var int Timestamp of course criteria completion {@link completion_criteria_completion::mark_complete()} */
     public $timecompleted;
 
-    /**
-     * Associated criteria object
-     * @access  private
-     * @var object  completion_criteria
-     */
+    /* @var completion_criterria Associated criteria object */
     private $_criteria;
 
     /**
      * Finds and returns a data_object instance based on params.
-     * @static abstract
      *
      * @param array $params associative arrays varname=>value
-     * @return object data_object instance or false if none found.
+     * @return data_object instance of data_object or false if none found.
      */
     public static function fetch($params) {
         $params['deleted'] = null;
@@ -121,7 +87,6 @@ class completion_criteria_completion extends data_object {
 
     /**
      * Finds and returns all data_object instances based on params.
-     * @static abstract
      *
      * @param array $params associative arrays varname=>value
      * @return array array of data_object insatnces or false if none found.
@@ -130,8 +95,8 @@ class completion_criteria_completion extends data_object {
 
     /**
      * Return status of this criteria completion
-     * @access  public
-     * @return  boolean
+     *
+     * @return bool
      */
     public function is_complete() {
         return (bool) $this->timecompleted;
@@ -141,8 +106,6 @@ class completion_criteria_completion extends data_object {
      * Mark this criteria complete for the associated user
      *
      * This method creates a course_completion_crit_compl record
-     * @access  public
-     * @return  void
      */
     public function mark_complete() {
         // Create record
@@ -166,9 +129,8 @@ class completion_criteria_completion extends data_object {
 
     /**
      * Attach a preloaded criteria object to this object
-     * @access  public
+     *
      * @param   $criteria   object  completion_criteria
-     * @return  void
      */
     public function attach_criteria(completion_criteria $criteria) {
         $this->_criteria = $criteria;
@@ -177,13 +139,12 @@ class completion_criteria_completion extends data_object {
     /**
      * Return the associated criteria with this completion
      * If nothing attached, load from the db
-     * @access  public
-     * @return  object completion_criteria
+     *
+     * @return completion_criteria
      */
     public function get_criteria() {
 
-        if (!$this->_criteria)
-        {
+        if (!$this->_criteria) {
             global $DB;
 
             $params = array(
@@ -199,10 +160,9 @@ class completion_criteria_completion extends data_object {
     }
 
     /**
-     * Return criteria status text for display in reports
-     * @see     completion_criteria::get_status()
-     * @access  public
-     * @return  string
+     * Return criteria status text for display in reports {@link completion_criteria::get_status()}
+     *
+     * @return string
      */
     public function get_status() {
         return $this->_criteria->get_status($this);
diff --git a/lib/completion/completion_criteria_course.php b/lib/completion/completion_criteria_course.php
index 5f7acf209e9..aa818d898ed 100644
--- a/lib/completion/completion_criteria_course.php
+++ b/lib/completion/completion_criteria_course.php
@@ -189,8 +189,8 @@ class completion_criteria_course extends completion_criteria {
         // Loop through completions, and mark as complete
         $rs = $DB->get_recordset_sql($sql);
         foreach ($rs as $record) {
-            $completion = new completion_criteria_completion((array)$record);
-            $completion->mark_complete($record->timecompleted);
+            $completion = new completion_criteria_completion($record, DATA_OBJECT_FETCH_BY_KEY);
+            $completion->mark_complete($record['timecompleted']);
         }
         $rs->close();
     }
diff --git a/lib/completion/completion_criteria_date.php b/lib/completion/completion_criteria_date.php
index dfe1717ed33..607cb8b0bed 100644
--- a/lib/completion/completion_criteria_date.php
+++ b/lib/completion/completion_criteria_date.php
@@ -179,8 +179,8 @@ class completion_criteria_date extends completion_criteria {
         // Loop through completions, and mark as complete
         $rs = $DB->get_recordset_sql($sql, array(time()));
         foreach ($rs as $record) {
-            $completion = new completion_criteria_completion((array)$record);
-            $completion->mark_complete($record->timeend);
+            $completion = new completion_criteria_completion($record, DATA_OBJECT_FETCH_BY_KEY);
+            $completion->mark_complete($record['timeend']);
         }
         $rs->close();
     }
diff --git a/lib/completion/completion_criteria_duration.php b/lib/completion/completion_criteria_duration.php
index bc2c8a07883..1f404c48d71 100644
--- a/lib/completion/completion_criteria_duration.php
+++ b/lib/completion/completion_criteria_duration.php
@@ -225,8 +225,7 @@ class completion_criteria_duration extends completion_criteria {
         $now = time();
         $rs = $DB->get_recordset_sql($sql, array($now, $now));
         foreach ($rs as $record) {
-
-            $completion = new completion_criteria_completion((array)$record);
+            $completion = new completion_criteria_completion($record, DATA_OBJECT_FETCH_BY_KEY);
 
             // Use time start if not 0, otherwise use timeenrolled
             if ($record->otimestart) {
diff --git a/lib/completion/completion_criteria_grade.php b/lib/completion/completion_criteria_grade.php
index c1ff8a07122..86b2e0b7e84 100644
--- a/lib/completion/completion_criteria_grade.php
+++ b/lib/completion/completion_criteria_grade.php
@@ -215,8 +215,8 @@ class completion_criteria_grade extends completion_criteria {
         // Loop through completions, and mark as complete
         $rs = $DB->get_recordset_sql($sql);
         foreach ($rs as $record) {
-            $completion = new completion_criteria_completion((array)$record);
-            $completion->mark_complete($record->timecompleted);
+            $completion = new completion_criteria_completion($record, DATA_OBJECT_FETCH_BY_KEY);
+            $completion->mark_complete($record['timecompleted']);
         }
         $rs->close();
     }
diff --git a/lib/completion/cron.php b/lib/completion/cron.php
index 281a9d76d25..d6e77d2fabd 100644
--- a/lib/completion/cron.php
+++ b/lib/completion/cron.php
@@ -322,7 +322,7 @@ function completion_cron_completions() {
             foreach ($completions as $params) {
                 $timecompleted = max($timecompleted, $params->timecompleted);
 
-                $completion = new completion_criteria_completion($params, false);
+                $completion = new completion_criteria_completion((array)$params, false);
 
                 // Handle aggregation special cases
                 if ($params->criteriatype == COMPLETION_CRITERIA_TYPE_ACTIVITY) {
diff --git a/lib/completion/data_object.php b/lib/completion/data_object.php
index c096c8e8bf4..9d862ba914a 100644
--- a/lib/completion/data_object.php
+++ b/lib/completion/data_object.php
@@ -1,85 +1,137 @@
 <?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/>.
 
-///////////////////////////////////////////////////////////////////////////
-//                                                                       //
-// NOTICE OF COPYRIGHT                                                   //
-//                                                                       //
-// Moodle - Modular Object-Oriented Dynamic Learning Environment         //
-//          http://moodle.com                                            //
-//                                                                       //
-// Copyright (C) 1999 onwards Martin Dougiamas  http://dougiamas.com     //
-//                                                                       //
-// This program 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 2 of the License, or     //
-// (at your option) any later version.                                   //
-//                                                                       //
-// This program 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:                          //
-//                                                                       //
-//          http://www.gnu.org/copyleft/gpl.html                         //
-//                                                                       //
-///////////////////////////////////////////////////////////////////////////
+/**
+ * Course completion critieria aggregation
+ *
+ * @package core_completion
+ * @category completion
+ * @copyright 2009 Catalyst IT Ltd
+ * @author Aaron Barnes <aaronb@catalyst.net.nz>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+
+/**
+ * Trigger for the new data_object api.
+ *
+ * See data_object::__constructor
+ */
+define('DATA_OBJECT_FETCH_BY_KEY',  2);
 
 /**
  * A data abstraction object that holds methods and attributes
- * @abstract
+ *
+ * @package core_completion
+ * @category completion
+ * @copyright 2009 Catalyst IT Ltd
+ * @author Aaron Barnes <aaronb@catalyst.net.nz>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 abstract class data_object {
-    /**
-     * Table that the class maps to in the database
-     * @var string $table
-     */
+
+    /* @var string Table that the class maps to in the database */
     public $table;
 
-    /**
-     * Array of required table fields, must start with 'id'.
-     * @var array $required_fields
-     */
+    /* @var array Array of required table fields, must start with 'id'. */
     public $required_fields = array('id');
 
     /**
      * Array of optional fields with default values - usually long text information that is not always needed.
      * If you want to create an instance without optional fields use: new data_object($only_required_fields, false);
-     * @var array $optional_fields
+     * @var array
      */
     public $optional_fields = array();
 
-    /**
-     * The PK.
-     * @var int $id
-     */
+    /* @var Array of unique fields, used in where clauses and constructor */
+    public $unique_fields = array();
+
+    /* @var int The primary key */
     public $id;
 
+
     /**
      * Constructor. Optionally (and by default) attempts to fetch corresponding row from DB.
-     * @param array $params an array with required parameters for this data object.
-     * @param boolean $fetch Whether to fetch corresponding row from DB or not,
-     *        optional fields might not be defined if false used
+     *
+     * If $fetch is not false, there are a few different things that can happen:
+     * - true:
+     *   load corresponding row from the database, using $params as the WHERE clause
+     *
+     * - DATA_OBJECT_FETCH_BY_KEY:
+     *  load corresponding row from the database, using only the $id in the WHERE clause (if set),
+     *  otherwise using the columns listed in $this->unique_fields.
+     *
+     * - array():
+     *   load corresponding row from the database, using the columns listed in this array
+     *   in the WHERE clause
+     *
+     * @param   array   $params     required parameters and their values for this data object
+     * @param   mixed   $fetch      if false, do not attempt to fetch from the database, otherwise see notes
      */
-    public function __construct($params=NULL, $fetch=true) {
-        if (!empty($params) and (is_array($params) or is_object($params))) {
-            if ($fetch) {
-                if ($data = $this->fetch($params)) {
-                    self::set_properties($this, $data);
-                } else {
-                    self::set_properties($this, $this->optional_fields);//apply defaults for optional fields
-                    self::set_properties($this, $params);
-                }
+    public function __construct($params = null, $fetch = true) {
 
-            } else {
-                self::set_properties($this, $params);
+        if (is_object($params)) {
+            throw new coding_exception('data_object params should be in the form of an array, not an object');
+        }
+
+        // If no params given, apply defaults for optional fields
+        if (empty($params) || !is_array($params)) {
+            self::set_properties($this, $this->optional_fields);
+            return;
+        }
+
+        // If fetch is false, do not load from database
+        if ($fetch === false) {
+            self::set_properties($this, $params);
+            return;
+        }
+
+        // Compose where clause only from fields in unique_fields
+        if ($fetch === DATA_OBJECT_FETCH_BY_KEY && !empty($this->unique_fields)) {
+            if (empty($params['id'])) {
+                $where = array_intersect_key($params, array_flip($this->unique_fields));
             }
-
+            else {
+                $where = array('id' => $params['id']);
+            }
+        // Compose where clause from given field names
+        } else if (is_array($fetch) && !empty($fetch)) {
+            $where = array_intersect_key($params, array_flip($fetch));
+        // Use entire params array for where clause
         } else {
-            self::set_properties($this, $this->optional_fields);//apply defaults for optional fields
+            $where = $params;
+        }
+
+        // Attempt to load from database
+        if ($data = $this->fetch($where)) {
+            // Apply data from database, then data sent to constructor
+            self::set_properties($this, $data);
+            self::set_properties($this, $params);
+        } else {
+            // Apply defaults for optional fields, then data from constructor
+            self::set_properties($this, $this->optional_fields);
+            self::set_properties($this, $params);
         }
     }
 
     /**
      * Makes sure all the optional fields are loaded.
+     *
      * If id present (==instance exists in db) fetches data from db.
      * Defaults are used for new instances.
      */
@@ -99,10 +151,12 @@ abstract class data_object {
 
     /**
      * Finds and returns a data_object instance based on params.
-     * @static abstract
      *
-     * @param array $params associative arrays varname=>value
-     * @return object data_object instance or false if none found.
+     * This function MUST be overridden by all deriving classes.
+     *
+     * @param array $params associative arrays varname => value
+     * @throws coding_exception This function MUST be overridden
+     * @return data_object instance  of data_object or false if none found.
      */
     public static function fetch($params) {
         throw new coding_exception('fetch() method needs to be overridden in each subclass of data_object');
@@ -111,7 +165,10 @@ abstract class data_object {
     /**
      * Finds and returns all data_object instances based on params.
      *
-     * @param array $params associative arrays varname=>value
+     * This function MUST be overridden by all deriving classes.
+     *
+     * @param array $params associative arrays varname => value
+     * @throws coding_exception This function MUST be overridden
      * @return array array of data_object instances or false if none found.
      */
     public static function fetch_all($params) {
@@ -120,8 +177,12 @@ abstract class data_object {
 
     /**
      * Factory method - uses the parameters to retrieve matching instance from the DB.
-     * @static final protected
-     * @return mixed object instance or false if not found
+     *
+     * @final
+     * @param string $table The table name to fetch from
+     * @param string $classname The class that you want the result instantiated as
+     * @param array $params Any params required to select the desired row
+     * @return object Instance of $classname or false.
      */
     protected static function fetch_helper($table, $classname, $params) {
         if ($instances = self::fetch_all_helper($table, $classname, $params)) {
@@ -137,7 +198,11 @@ abstract class data_object {
 
     /**
      * Factory method - uses the parameters to retrieve all matching instances from the DB.
-     * @static final protected
+     *
+     * @final
+     * @param string $table The table name to fetch from
+     * @param string $classname The class that you want the result instantiated as
+     * @param array $params Any params required to select the desired row
      * @return mixed array of object instances or false if not found
      */
     public static function fetch_all_helper($table, $classname, $params) {
@@ -185,7 +250,8 @@ abstract class data_object {
 
     /**
      * Updates this object in the Database, based on its object variables. ID must be set.
-     * @return boolean success
+     *
+     * @return bool success
      */
     public function update() {
         global $DB;
@@ -205,7 +271,8 @@ abstract class data_object {
 
     /**
      * Deletes this object from the database.
-     * @return boolean success
+     *
+     * @return bool success
      */
     public function delete() {
         global $DB;
@@ -228,6 +295,8 @@ abstract class data_object {
 
     /**
      * Returns object with fields and values that are defined in database
+     *
+     * @return stdClass
      */
     public function get_record_data() {
         $data = new stdClass();
@@ -248,6 +317,7 @@ abstract class data_object {
      * Records this object in the Database, sets its id to the returned value, and returns that value.
      * If successful this function also fetches the new object data from database and stores it
      * in object properties.
+     *
      * @return int PK ID if successful, false otherwise
      */
     public function insert() {
@@ -274,6 +344,8 @@ abstract class data_object {
      * each variable in turn. If the DB has different data, the db's data is used to update
      * the object. This is different from the update() function, which acts on the DB record
      * based on the object.
+     *
+     * @return bool True for success, false otherwise.
      */
     public function update_from_db() {
         if (empty($this->id)) {
@@ -294,7 +366,10 @@ abstract class data_object {
     /**
      * Given an associated array or object, cycles through each key/variable
      * and assigns the value to the corresponding variable in this object.
-     * @static final
+     *
+     * @final
+     * @param data_object $instance
+     * @param array $params
      */
     public static function set_properties(&$instance, $params) {
         $params = (array) $params;
@@ -310,8 +385,8 @@ abstract class data_object {
      * deleted in the database. Default does nothing, can be overridden to
      * hook in special behaviour.
      *
-     * @param bool $deleted
+     * @param bool $deleted Set this to true if it has been deleted.
      */
-    function notify_changed($deleted) {
+    public function notify_changed($deleted) {
     }
 }
diff --git a/lib/completionlib.php b/lib/completionlib.php
index cce41d0d922..cc0eb5b3dd6 100644
--- a/lib/completionlib.php
+++ b/lib/completionlib.php
@@ -293,8 +293,9 @@ class completion_info {
      */
     public function get_user_completion($user_id, $criteria) {
         $params = array(
+            'course'        => $this->course_id,
+            'userid'        => $user_id,
             'criteriaid'    => $criteria->id,
-            'userid'        => $user_id
         );
 
         $completion = new completion_criteria_completion($params);
@@ -336,7 +337,7 @@ class completion_info {
             // Build array of criteria objects
             $this->criteria = array();
             foreach ($records as $record) {
-                $this->criteria[$record->id] = completion_criteria::factory($record);
+                $this->criteria[$record->id] = completion_criteria::factory((array)$record);
             }
         }