Multiple Reference Timelines: Back-end models, controllers extensions

[purfectliterature]

Closes #3092.

Warning Merge this PR together with the front-end extensions in #5631! These PRs shall remain as Draft until this feature is ready to ship.

Feature overview

Multiple Reference Timelines (internally abbreviated as MRT) is a feature that allows different students to follow different assignment opening and closing times, thus following different timelines. This feature is useful for teachers who manage different classes that may have different homework deadlines, yet whose students still belong to the same course.

The building blocks for this feature was originally introduced in #3130, but the application-level implementations were deferred and tracked in #3092. This PR, and subsequent ones, aim to complete these deferred works.

For brevity, reference timelines and reference times may be referred to as timelines and times in these documentations. Personal times will still be referred to as is.

Notable changes

• ℹ️ No structural changes to database schema. Follows the schema implemented in Migration + models for multiple reference timelines #3130.
• ✈️ One migration: add title and weight columns to course_reference_timelines table.
• 🔥 Course::LessonPlan::Item#reference_time_for now supports non-default (custom) reference timelines.
• 🔥 Add validations to Course::ReferenceTime
• 🔥 Add validations to Course::ReferenceTimeline
• 🔥 Add CRUD endpoints for Course::ReferenceTime
• 🔥 Add CRUD endpoints for Course::ReferenceTimeline
• 🔨 Add model, controller tests, and test helpers for these validations and invariants

Database schema

New routes

• GET /courses/:id/timelines
• GET /courses/:id/timelines/:id
• POST /courses/:id/timelines
• PATCH /courses/:id/timelines/:id
• DELETE /courses/:id/timelines/:id
• POST /courses/:id/timelines/:id/times
• PATCH /courses/:id/timelines/:id/times/:id
• DELETE /courses/:id/timelines/:id/times/:id
• PATCH /courses/:id/users/assign_timeline

Pending

Pending work	Tracked in	Status
Front-end: Timeline Designer	#4202	#5631
Front-end: Assigning students to timelines	#4202	#5631
Back-end: Closing reminders to follow custom times	#3240	Deferred
Back-end: Address the remaining # TODO(#3092)s	#3092	Deferred

todo: to add invariants, sanity checks, and test plan descriptions (tests have already been added)

[ekowidianto]

Thanks and good work! @purfectliterature
Some nits and notes below:

• Remove app/mailers/.keep.
• Add tests to items feature tests (eg submission, video and survey) to ensure that the correct time is selected/shown to a user when the user is assigned to a different timeline.
• I believe you will still make more changes to the API response so I wont comment much yet on the jbuilder as of now. Note: Remember to pass the permissions to the frontend too.
• For the case when an item has different/no start_time, end_time and bonus_end_time in the default timeline as compared to those in an alternative timeline, line 22 in app/views/course/assessment/assessments/show.json.jbuilder may break. start_time, end_time, bonus_end_time should be loaded via time_for instead of accessing the value directly from the item (which only loads the default time). I have listed a few other places below to check (May not be complete, please help to check if I miss anything):
  • app/models/course/survey/response.rb line 27
  • app/services/course/assessment/submission/calculate_exp_service.rb line 22 and line 23
  • app/views/course/assessment/assessments/show.json.jbuilder line 22 and line 43
  • app/views/course/survey/surveys/_survey.json.jbuilder line 4 to 6
• Check AR queries using default_reference_time. Seems like there's a few places that use the default timeline only:
  • app/models/course/video.rb
  • app/models/components/course/surveys_ability_component.rb
  • app/controllers/course/courses_controller.rb
  • app/controllers/course/statistics/aggregate_controller.rb
  • app/models/components/course/surveys_ability_component.rb (TODO(#3092))
• Remove TODO(#3092) in the course_user model file. It's not relevant anymore.

Note to self:

• Check object duplication from a course with multiple timelines to another course with single/multiple timelines

[ekowidianto]

We may need to revisit this.. for unsubmitted items, personal_time might be recomputed (and removed) if the new reference time of a new reference timeline is created with no end_at