Exception - count(): Argument #1 ($value) must be of type Countable|array, null given

[Richardvi]

Describe the bug
A clear and concise description of what the bug is. We are using Moodle 4.3.2

When clicking on the Rubric Breakdown Report the following error occurs: Exception - count(): Argument #1 ($value) must be of type Countable|array, null given

To Reproduce
Screenshots

Our Rubric looks like this:

[marcusgreen]

Thanks Richard, any chance you can give me access to a course where this happens?

[Richardvi]

That is kinda difficult to realize as we do not create accounts in our own Moodle, everyone logs in using ADFS.

What I could do is create a backup from this specific assignment and send it to you? Would that help?

Also, we are using multiple attempts in assignments. Could that be a problem in the report?

[marcusgreen]

Yes a backup/restore would probably help and yes multiple attempts might be an issue (though I have a vague recollection of testing against that).
This report does a similar thing and it would be interesting to know if it runs without error on your site..
https://github.com/brickfield/moodle-gradereport_rubrics

[CristhianBohorquez]

Error message

Exception - count(): Argument #1 ($value) must be of type Countable|array, null given

More information about this error

Debug info:
Error code: generalexceptionmessage×Dismiss this notification
Stack trace:
line 54 of /report/advancedgrading/guide.php: TypeError thrown
×Dismiss this notification
Output buffer:

Error: mdb->get_record() found more than one record!

• line 1691 of /lib/dml/moodle_database.php: call to debugging()
• line 50 of /report/advancedgrading/locallib.php: call to moodle_database->get_record_sql()
• line 178 of /report/advancedgrading/locallib.php: call to get_grading_definition()
• line 39 of /report/advancedgrading/guide.php: call to init()

Invalid get_string() identifier: 'pluginname' or component 'gradingform_'. Perhaps you are missing $string['pluginname'] = ''; in /lang/en/gradingform_.php?

• line 356 of /lib/classes/string_manager_standard.php: call to debugging()
• line 7414 of /lib/moodlelib.php: call to core_string_manager_standard->get_string()
• line 99 of /report/advancedgrading/locallib.php: call to get_string()
• line 186 of /report/advancedgrading/locallib.php: call to header_fields()
• line 39 of /report/advancedgrading/guide.php: call to init()

Error: mdb->get_record() found more than one record!

• line 1691 of /lib/dml/moodle_database.php: call to debugging()
• line 50 of /report/advancedgrading/locallib.php: call to moodle_database->get_record_sql()
• line 187 of /report/advancedgrading/locallib.php: call to get_grading_definition()
• line 39 of /report/advancedgrading/guide.php: call to init()

Looking into the plugin function
https://github.com/marcusgreen/moodle-report_advancedgrading/blob/main/locallib.php#L41

/**

• Get the structure of this grading definition
• @param int $assignid
• @return \stdClass
  */
  function get_grading_definition(int $assignid): \stdClass {
  global $DB;
  $sql = "SELECT gdef.id AS definitionid, ga.activemethod, gdef.name AS definition
  FROM {assign} assign
  JOIN {course_modules} cm ON cm.instance = assign.id
  JOIN {context} ctx ON ctx.instanceid = cm.id
  JOIN {grading_areas} ga ON ctx.id=ga.contextid
  JOIN {grading_definitions} gdef ON ga.id = gdef.areaid
  WHERE assign.id = :assignid";
  $definition = $DB->get_record_sql($sql, ['assignid' => $assignid]);
  return $definition;
  }

The current query has the potential to join to unrelated course module or context records, that is why it is happening the error.

$sql = "SELECT gdef.id AS definitionid, ga.activemethod, gdef.name AS definition
FROM {assign} assign
JOIN {course_modules} cm ON cm.instance = assign.id
JOIN {modules} m ON m.id = cm.module AND m.name = 'assign'
JOIN {context} ctx ON ctx.instanceid = cm.id AND ctx.contextlevel = 70
JOIN {grading_areas} ga ON ctx.id=ga.contextid
JOIN {grading_definitions} gdef ON ga.id = gdef.areaid
WHERE assign.id = :assignid"

[marcusgreen]

I will investigate

[Richardvi]

I still had this on my to do list, but unfortunately I was unable to share the backup as there's personalized data inside the course.

So thanks to @CristhianBohorquez for sharing additional info.

I think the trouble is the many 0 points in the rubric.

[mikehenry1979-bah]

Had this same exception, the query above was returning two grade_definitions rows for one assignment ID, and upon examination one row had a mismatch between gdef.method and ga.activemethod. Therefore the next part of code was loading from the wrong mdl_gradingform_x_criteria table (x = guide or rubric) and not populating $data['criteria'], causing the count() null exception on the rubric.php page. What fixed it here was to add an AND onto the last join, JOIN {grading_definitions} gdef ON ga.id = gdef.areaid AND gdef.method = ga.activemethod.

[mikehenry1979-bah]

Alternatively, after I removed my patch and the error came back, a site admin was able to fix the error by deleting the grading guide from the assignment and ensuring that the assignment and advanced grading settings were both set to rubric.