add omit_from_final_grade to course config

refs TALLY-301

test plan:
 - migration runs

Change-Id: Ic8ba3cb0db3c722bd1e804dd28d2b3e6957b383f
Reviewed-on: https://gerrit.instructure.com/c/rollcall-attendance/+/217597
Tested-by: Service Cloud Jenkins <[email protected]>
Reviewed-by: Simon Williams <[email protected]>
QA-Review: Spencer Olson <[email protected]>
Product-Review: Keith Garner <[email protected]>

config/application.rb

@@ -48,6 +48,8 @@ class Application < Rails::Application
 
     config.action_dispatch.default_headers = { 'X-Frame-Options' => 'ALLOWALL' }
 
+    config.autoload_paths += %w[lib]
+
     # Our deploy tooling exports a DATABASE_URL like:
     # mysql://user:pass@db:port/database, so handle that
     module MysqlProtocolResolver

db/migrate/20191118151647_add_omit_from_final_grade_to_course_config.rb

@@ -0,0 +1,44 @@
+#
+# Copyright (C) 2019 - present Instructure, Inc.
+#
+# This file is part of Rollcall.
+#
+# Rollcall is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Rollcall is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+
+class AddOmitFromFinalGradeToCourseConfig < ActiveRecord::Migration[5.2]
+  disable_ddl_transaction!
+
+  def up
+    if ActiveRecord::ConnectionAdapters.const_defined?("Mysql2Adapter") && ActiveRecord::Base.connection.instance_of?(ActiveRecord::ConnectionAdapters::Mysql2Adapter)
+      # Look at https://dev.mysql.com/doc/refman/5.6/en/innodb-online-ddl-operations.html#online-ddl-column-operations
+      # for some additional information. We're trying to do the database changes in place without needing a copy table,
+      # the MySQL default. We're on a new enough MySQL that we should be able to the add the column, set the default,
+      # and set it NOT NULL all without a copy nor a lock.
+      execute <<~SQL
+        ALTER TABLE course_configs
+        ADD COLUMN omit_from_final_grade BOOL DEFAULT false NOT NULL,
+        ALGORITHM=INPLACE,
+        LOCK=NONE;
+      SQL
+    else
+      add_column :course_configs, :omit_from_final_grade, :boolean
+      change_column_default :course_configs, :omit_from_final_grade, false
+      DataFixup::BackfillNulls.run(CourseConfig, :omit_from_final_grade, new_value: false, batch_size: 1000)
+      change_column_null(:course_configs, :omit_from_final_grade, false)
+    end
+  end
+
+  def down
+    remove_column :course_configs, :omit_from_final_grade
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2015_08_13_210811) do
+ActiveRecord::Schema.define(version: 2019_11_18_151647) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -70,6 +70,7 @@
     t.datetime "updated_at"
     t.string "view_preference"
     t.string "tool_consumer_instance_guid"
+    t.boolean "omit_from_final_grade", default: false, null: false
     t.index ["course_id", "tool_consumer_instance_guid"], name: "index_course_configs, uniquely", unique: true
   end
 

lib/data_fixup/backfill_nulls.rb

@@ -0,0 +1,23 @@
+#
+# Copyright (C) 2019 - present Instructure, Inc.
+#
+# This file is part of Rollcall.
+#
+# Rollcall is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Rollcall is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+
+module DataFixup::BackfillNulls
+  def self.run(klass, field, new_value:, batch_size: 1000)
+    objects_to_backfill = klass.where(field => nil)
+    objects_to_backfill.in_batches(of: batch_size).update_all(field => new_value, updated_at: Time.zone.now)
+  end
+end

spec/factories/factories.rb

@@ -60,4 +60,11 @@
     cached_account {}
     descendant {}
   end
+
+  factory :course_config do
+    course_id 1
+    tardy_weight 0.8
+    omit_from_final_grade false
+    tool_consumer_instance_guid "abc123"
+  end
 end

spec/lib/data_fixup/backfill_nulls_spec.rb

@@ -0,0 +1,22 @@
+require 'spec_helper'
+
+describe DataFixup::BackfillNulls do
+  context '.run' do
+    before do
+      @course1 = create(:course_config, course_id: 1234, tardy_weight: nil)
+      @course2 = create(:course_config, course_id: 1235, tardy_weight: 0.8)
+    end
+
+    it 'replaces null values of "field" with the new value' do
+      expect {
+        DataFixup::BackfillNulls.run(CourseConfig, :tardy_weight, new_value: 0.5)
+      }.to change { @course1.reload.tardy_weight }.from(nil).to(0.5)
+    end
+
+    it 'does not replace not-null values of "field"' do
+      expect {
+        DataFixup::BackfillNulls.run(CourseConfig, :tardy_weight, new_value: 0.5)
+      }.not_to change { @course2.reload.tardy_weight }.from(0.8)
+    end
+  end
+end