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Bug
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Resolution: Unresolved
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Blocker
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None
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4.1 regressions, 4.1.9
After upgrading Moodle 3.9.22 to 4.1.9, when attempting to do anything related to a quiz containing random questions, there are errors.
- Users of all roles are presented with the error “There are not enough questions in category to create the question”.
- An editingteacher, viewing the questions for a quiz is presented with the error “Faulty random question! Please delete this question.” for each question." (quiz/notenoughrandomquestions).
I've discovered that the 2022020200.04 upgrade step produces the below query.
INSERT
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INTO
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mdl_question_set_references
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(usingcontextid, component, questionarea, itemid, questionscontextid, filtercondition) SELECT
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c.id,
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'mod_quiz', |
'slot', |
qs.id,
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qc.contextid,
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CONCAT('
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{
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"questioncategoryid": "', |
q.category,
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'",
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"includingsubcategories": "', |
qs.includingsubcategories,
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'"
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}
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')
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FROM
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mdl_question q
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INNER JOIN
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mdl_quiz_slots qs
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on q.id = qs.questionid
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INNER JOIN
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mdl_course_modules cm
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ON cm.instance = qs.quizid
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AND cm.module = '16' |
INNER JOIN
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mdl_context c
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ON cm.id = c.instanceid
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AND c.contextlevel = '70' |
INNER JOIN
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mdl_question_categories qc
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ON qc.id = q.category
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WHERE
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q.qtype = 'random'; |
The CONCAT fails to consider that quiz_slots.includingsubcategories is nullable. If quiz_slots.includingsubcategories is null the entire CONCAT returns NULL. The next step uses the result of this concat to populate the question_set_references.filtercondition value and sets it to null, breaking the random questions.
The solution is to use COALESCE to return 0 string if qs.includingsubcategories is null.
CONCAT('
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{
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"questioncategoryid": "', q.category, '", |
"includingsubcategories": "', COALESCE(qs.includingsubcategories, '0'), '" |
}
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')
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This creates the expected JSON
{"questioncategoryid":"56154","includingsubcategories":"0"} |
