Improve how homeroom grades are stored

[kevinrobinson]

Part of #1693.

This came up in feedback from an AP. I was initially assuming this was a small number of classrooms, most of which are substantially separate special education classrooms. I went to confirm that but looks like there's more going on:

Homeroom.all.size
class_list_homerooms = Homeroom.all.where(grade: ['KF', '1', '2', '3', '4', '5']);nil
class_list_homerooms.size

mixed_homerooms = class_list_homerooms.select {|homeroom| homeroom.students.map(&:grade).any? {|grade| grade != homeroom.grade } };nil
mixed_homerooms.size
=> 0.6241610738255033

So that shows a large fraction of classrooms have some mismatch around grade levels. Spot checking a few, it seems this might be partially an Insights bug.

[kevinrobinson]

It looks like there's a method https://github.com/studentinsights/studentinsights/blob/master/app/models/homeroom.rb#L12 for updating the Homeroom grade but grepping around it seems to me like it's never called. @alexsoble does any of this ring bells for you? No worries if not, I can look more next week.

[alexsoble]

@kevinrobinson It's invoked as a hook here:

has_many :students, after_add: :update_grade

[kevinrobinson]

@alexsoble ha okay great thanks! That's what I thought but failed at grepping :)

[kevinrobinson]

This is an issue today, I patched the db manually:

step 1, clear data bugs (I did not investigate how or why yet):

clear_mismatches = Homeroom.all.includes(:students).select {|homeroom| grades = homeroom.students.map(&:grade).uniq; grades.size == 1 && grades.first != homeroom.grade };nil


k8_clear_mismatches = clear_mismatches.select {|h| !h.school.is_high_school? };nil
puts k8_clear_mismatches.map {|h| [h.id, h.grade, h.students.map(&:grade).uniq, h.school.name].join("\t") }.join("\n");nil

step 2, more complicated homerooms that maybe accurate or data bugs:

mixed_grade_homerooms = Homeroom.all.includes(:students).select {|homeroom| !homeroom.school.is_high_school? }.select {|homeroom| grades = homeroom.students.map(&:grade).uniq; grades.size > 1 };nil
mixed_grade_homerooms.size

[kevinrobinson]

The root problem here is that a homeroom doesn't have a grade in the import, and there are mixed grade homerooms. So the approach in https://github.com/studentinsights/studentinsights/blob/master/app/models/homeroom.rb#L12 won't be accurate over time.

I think ideally we'd remove the Homeroom relation altogether in favor of Sections for K8 before the rollover this summer.

[kevinrobinson]

Going to split this out of #1722 and leave it for later this summer.