Using the moodle gradebook library API

Leveraging the grade report lib.php

When I initially built a custom grade report, I looked at the user grade report as an example of how to build/access score averages and percentages of course completed figures.

 I opened grade/report/user/index.php and tried to determine how it was generating that nice user grade report, this one.

Eventually, I stopped on this line

$report = new grade_report_user($courseid, $gpr, $context, $userid);

This line is creating a new object grade_report_user and is passing in both the course and user id.

 I found the grade_report_user class in the grade/report/user/lib.php file. It contains a constructor that seems to do all the work of calculating the grades for each user and course passed into it. In my report, I had to ensure I had created both the $context and $gpr variables to pass into the object constructor. I found both of these statements in the lib.php file and copied them into my custom file.

This is the code from the index.php file in my custom progress report.

$courseid = required_param('id', PARAM_INT);
$context = get_context_instance(CONTEXT_COURSE, $course->id);
$gpr = new grade_plugin_return(array('type'=>'report', 'plugin'=>'progress', 'courseid'=>$courseid, 'userid'=>$rec->userid));
$uObj = new grade_report_user($courseid, $gpr, $context, $rec->userid);
 $uObj->setup_table();
$uObj->fill_table();
$tdata = $uObj->tabledata;

The setup_table and fill_table are public functions of the grade_report_user class. Using var_dump() liberally during this process on $context, $uObj, and $tdata was very helpful. The $rec->userid is provided by a query result that I am looping over while creating a grade_report_user object for each user. Like this:

$students = getStudents($courseid); //getStudents is a function I created

foreach($students as $rec){
   $courseid = required_param('id', PARAM_INT); // course id 
  $context = get_context_instance(CONTEXT_COURSE, $course->id); 
  $gpr = new grade_plugin_return(array('type'=>'report', 'plugin'=>'progress', 'courseid'=>$courseid, 'userid'=>$rec->userid)); 
  $uObj = new grade_report_user($courseid, $gpr, $context, $rec->userid);   $uObj->setup_table();
 $uObj->fill_table();
 $tdata = 
$uObj->tabledata;
  . 
  . 
  . 
}

I then created another smaller data structure to hold the two pieces of data for each student that I wanted

foreach($tdata as $i => $td){
         //var_dump($tdata);
         if($i === 1 ){
             //var_dump($i);
             $scores['grade'] = $td['percentage']['content'];          
         }elseif($i === 3){
             //var_dump($td);
             $scores['percentcomplete'] = $td['percentage']['content'];
         }
}

Notice, continued use of var_dump()!

I then simply outputted the result like this:
           
'.$scores['grade'].'
'.$scores['percentcomplete'].'

The end result is a progress report that lists all the course students current grade and % of course completed in a nice tidy summary format - where the score data is IDENTICAL to that of the more detailed user grade report!

  Moral of the story?

It took me awhile to work through how to do this using the native API, but in the end the results are consistent. Use var_dump() to evaluate what the API is returning to you.  Use the native functionality rather than trying to recreate the wheel.  Resist the tendency to retreat into a corner and re-write code because you cannot figure out how the existing code is working.  Finally, moodles' gradebook calculations are complex as is the underlying table structure.  If you do not grok it initially, come back to it over and over and eventually you will win.