Skip submissions if any have been graded in next submitter view

[EerikSaksi]

Fixes #1196

Description

What?

Submitters whose older work was already graded weren't skipped when pressing the "next submitter" link in manual assesment.

Why?
We shouldn't show a user whose work has already been graded even if they have later work.

How?

Rather than checking if the most recent submission has been graded, we skip submitters based on if any of their submissions for this exercise has been graded

Fixes #1196

Testing

What type of test did you run?

• Accessibility test using the WAVE extension.
• Django unit tests.
• Selenium tests.
• Other test. (Add a description below)
• Manual testing.

In addition to unit tests I ensured that after grading the latest assesment the next submitter link takes you correctly. I also manually added a grader to the older work of the first user and ensured that this user was skipped even if their latest submission wasn't graded.

Did you test the changes in

• Chrome
• Firefox
• This pull request cannot be tested in the browser.

Think of what is affected by these changes and could become broken

Translation

• Did you modify or add new strings in the user interface? (Read about how to create translation)

Programming style

• Did you follow our style guides?
• Did you use Python type hinting in all functions that you added or edited? (type hints for function parameters and return values)

Have you updated the README or other relevant documentation?

• documents inside the doc directory.
• README.md.
• Aplus Manual.
• Other documentation (mention below which documentation).

Is it Done?

• Reviewer has finished the code review
• After the review, the developer has made changes accordingly
• Customer/Teacher has accepted the implementation of the feature

Clean up your git commit history before submitting the pull request!

[markkuriekkinen]

I think the query for the latest submissions of each submitter is still not working correctly.

Remember also that a submission may have multiple submitters and those cases should also be tested. The current unit tests use too few submissions and different submitters to reveal significant bugs.

I am pushing a new commit that fixes minor issues in the current unit tests.

[markkuriekkinen]

A few lines above, user2_other_exercise_submission is actually submitted by self.user and not self.user2.

[markkuriekkinen]

The comment says grading in an older submission (not latest) should also mean user1 is skipped, but aren't you grading the latest submission right here?

[markkuriekkinen]

I don't think the annotatecall for the latest submissions is working correctly. It doesn't seem to find the latest submission for each submitter separately.

[markkuriekkinen]

I looked at the SQL query produced by the "submissions annotate latest` statement.

(submissions.annotate(latest=Max('submission_time'))
    .filter(submission_time=F('latest'))
    .order_by('latest')))

This GROUP BY part looks suspicious since it is not grouping by submitters. See the whole query below.

GROUP BY "exercise_submission"."id"
HAVING "exercise_submission"."submission_time" = MAX("exercise_submission"."submission_time")

The whole SQL query:

SELECT "exercise_submission"."id",
       "exercise_submission"."submission_time",
       "exercise_submission"."hash",
       "exercise_submission"."exercise_id",
       "exercise_submission"."grader_id",
       "exercise_submission"."feedback",
       "exercise_submission"."assistant_feedback",
       "exercise_submission"."status",
       "exercise_submission"."grade",
       "exercise_submission"."grading_time",
       "exercise_submission"."late_penalty_applied",
       "exercise_submission"."force_exercise_points",
       "exercise_submission"."service_points",
       "exercise_submission"."service_max_points",
       "exercise_submission"."submission_data",
       "exercise_submission"."grading_data",
       "exercise_submission"."meta_data",
       MAX("exercise_submission"."submission_time") AS "latest"
  FROM "exercise_submission"
 INNER JOIN "exercise_submission_submitters"
    ON ("exercise_submission"."id" = "exercise_submission_submitters"."submission_id")
 WHERE ("exercise_submission"."exercise_id" = 61 AND "exercise_submission_submitters"."userprofile_id" = 7)
 GROUP BY "exercise_submission"."id"
HAVING "exercise_submission"."submission_time" = MAX("exercise_submission"."submission_time")
 ORDER BY "latest" ASC

I think the part for querying a single user ("exercise_submission_submitters"."userprofile_id" = 7) came from the previous submitter (prev GET query parameter):

previous_submission_time = submissions.filter(submitters__id=previous_user_id).first().submission_time

[EerikSaksi]

I decided to try to try reimplement it by making small changes to the original query and managed to create a query which seems to provide the correct behavior for multiple users, and seems to group users based on their profile and sort them based on their earliest submission

submitters = (UserProfile.objects
		.filter(submissions__exercise=self.exercise)
		.annotate(
				count_assessed=Count(
						'submissions__id',
						filter=(Q(submissions__grader__isnull=False)),
				),
				earliest_submission=Min('submissions__submission_time'),
		)
		.order_by('earliest_submission'))

SELECT
  "userprofile_userprofile"."id",
  "userprofile_userprofile"."user_id",
  "userprofile_userprofile"."language",
  "userprofile_userprofile"."student_id",
  "userprofile_userprofile"."organization",
  COUNT("exercise_submission_submitters"."submission_id") FILTER (
    WHERE
      "exercise_submission"."grader_id" IS NOT NULL
  ) AS "count_assessed",
  MIN("exercise_submission"."submission_time") AS "earliest_submission",
  "auth_user"."id",
  "auth_user"."password",
  "auth_user"."last_login",
  "auth_user"."is_superuser",
  "auth_user"."username",
  "auth_user"."first_name",
  "auth_user"."last_name",
  "auth_user"."email",
  "auth_user"."is_staff",
  "auth_user"."is_active",
  "auth_user"."date_joined"
FROM
  "userprofile_userprofile"
  LEFT OUTER JOIN "exercise_submission_submitters" ON (
    "userprofile_userprofile"."id" = "exercise_submission_submitters"."userprofile_id"
  )
  LEFT OUTER JOIN "exercise_submission" ON (
    "exercise_submission_submitters"."submission_id" = "exercise_submission"."id"
  )
  INNER JOIN "auth_user" ON (
    "userprofile_userprofile"."user_id" = "auth_user"."id"
  )
WHERE
  "exercise_submission"."exercise_id" = 25
GROUP BY
  "userprofile_userprofile"."id",
  "auth_user"."id"
ORDER BY
  "earliest_submission" ASC