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updates to versioning documentation

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gustav_delius
2005-05-25 22:23:17 +00:00
parent 41fcf8cfc4
commit a2bb02cce2
1 changed files with 40 additions and 31 deletions
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mod/quiz/doc/versioning.html
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@@ -31,8 +31,23 @@ The first goal, namely keeping around old questions, is easily achieved. They
are just not deleted any more. However, this is not enough; it is also necessary
to store which questions are versions of others. To achieve this goal, there is
an additional table, which stores the versioning information:
<code>quiz_question_versions</code>. Finally, there is a cosmetic issue. If all
old versions of questions are kept around this would horribly clutter the
<code>quiz_question_versions</code>.
</p><p>
When a question is replaced for which there are already student attempts then
all the attempt data gets associated to the new version of the question and is
re-graded. This requires the question ids in the <code>quiz_attempts</code>,
<code>quiz_states</code> and <code>quiz_newest_states</code> tables to be
replaced by the new id. However we do also want to be able to reconstruct
the quiz the way the student saw it when he gave his answers. For that purpose
the id of the original question is always preserved in the 'originalquestion'
field of the <code>quiz_states</code> table.
</p><p>
If all
old versions of questions are kept around this could horribly clutter the
editing interface. Therefore a field called <code>hidden</code> was added to the
<code>quiz_questions</code> table and all old versions of edited questions are
automatically hidden. When this flag is set to 1 the question is not displayed
@@ -71,10 +86,12 @@ checked for that quiz as well.
<a name='database'></a><h2>Database</h2>
<p>
The changes to the database structure are limited to an added field
(<code>hidden</code>) in the <code>quiz_questions</code> table and an additional
table called <code>quiz_question_versions. However, dealing with the
<code>quiz_questions</code> table has become slightly more complicated.
The changes to the database structure are limited to an
added field (<code>hidden</code>) in the
<code>quiz_questions</code> table and an additional table called
<code>quiz_question_versions</code>. However, dealing with the
<code>quiz_questions</code> table has become slightly more
complicated.
</p><p>
@@ -104,15 +121,15 @@ the order shown below (compare with <strong>question.php</strong>):
<ul>
<li>
First a new record is inserted into the <code>quiz_question_states</code>
table for each affected quiz (i.e. each quiz in which the questin was
First a new record is inserted into the <code>quiz_question_versions</code>
table for each affected quiz (i.e. each quiz in which the question was
replaced).
</li><li>
Then, for each affected quiz, the <code>question</code> field is updated
with a comma separated list of question ids, where the old question id is
replaced with the new one.
Then, for each affected quiz, the comma separated list of question ids in the
<code>question</code> field is updated by replacing the old question id with
the new one.
</li><li>
@@ -121,29 +138,21 @@ the order shown below (compare with <strong>question.php</strong>):
</li><li>
Finally, if a question has been versioned for the first time after a quiz
has been attempted, the <code>originalquestion</code> field in the
<code>quiz_states</code> table (this is determined by the
<code>originalquestion</code> field beeing set to '0').
In all attempts belonging to the old question the comma-separated list of
question ids in the <code>layout</code> field are changed by replacing the
old id by the new one.
</li><li>
<p style="color:red;">
Question for Gustav:<br />
Should we also update the attempt->layout field at this point? Or do we use
that to determine how the student's attempt actually looked when they took
the quiz?
<br />
That's what is causing bug #3311: the attempts->layout field is not updated,
so there are question ids in <code>attempts->layout</code>, which don't have
instances associated with them. However, we need information from the
<code>quiz_question_instances</code> table (<code>grade</code>, which
becomes <code>question->maxgrade</code> and less importantly, I think, the
instance id, which becomes <code>question->instance</code>).
<br />
In the remaining text I assume that we don't change
<code>attempt->layout</code>.
</p>
All states belonging to the old question are made to belong to the new
version by changing the id in the 'question' field. However if we are
replacing the original question then the id of this original version
is stored in the <code>originalquestion</code> field.
</li><li>
Finally we have to change the <code>questionid</code> field in <code>
quiz_newest_states</code>.
</li>
</ul>