cheap hack to skip overriding assignments

refs CNVS-6747

Test plan:
  * Make sure the new assignments index page still shows correct dates
    (test in a course that has assignments with and without overrides)
  * Test the assignments index api action and make sure it returns the
    right dates too

Change-Id: Ibb6baaa5009fe95b68e160af2fb4e91d5ac8ef37
Reviewed-on: https://gerrit.instructure.com/22612
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Simon Williams <simon@instructure.com>
QA-Review: Amber Taniuchi <amber@instructure.com>
Product-Review: Cameron Matheson <cameron@instructure.com>

Author: cmatheson

app/controllers/assignment_groups_controller.rb

@@ -81,6 +81,16 @@ def index
 
         params[:override_assignment_dates] ||= true
         override_dates = value_to_boolean(params[:override_assignment_dates])
+
+        if override_dates
+          assignments_with_overrides = @context.assignments.active.except(:order)
+                                       .joins(:assignment_overrides)
+                                       .select("assignments.id")
+                                       .uniq
+          assignments_without_overrides = @groups.flat_map(&:active_assignments) -
+            assignments_with_overrides
+          assignments_without_overrides.each { |a| a.has_no_overrides = true }
+        end
       end
 
       respond_to do |format|

app/controllers/assignments_api_controller.rb

@@ -326,6 +326,14 @@ def index
         submissions = {}
       end
 
+      if override_dates
+        assignments_with_overrides = @assignments.joins(:assignment_overrides)
+          .select("assignments.id")
+        @assignments = @assignments.all
+        assignments_without_overrides = @assignments - assignments_with_overrides
+        assignments_without_overrides.each { |a| a.has_no_overrides = true }
+      end
+
       hashes = @assignments.map do |assignment|
         submission = submissions[assignment.id]
         assignment_json(assignment, @current_user, session,

lib/assignment_override_applicator.rb

@@ -23,6 +23,12 @@ module AssignmentOverrideApplicator
   def self.assignment_overridden_for(assignment_or_quiz, user)
     return assignment_or_quiz if assignment_or_quiz.overridden_for?(user)
 
+    # this is a cheap hack to avoid unnecessary work (especially stupid
+    # simply_versioned queries)
+    if assignment_or_quiz.has_no_overrides
+      return setup_overridden_clone(assignment_or_quiz)
+    end
+
     overrides = self.overrides_for_assignment_and_user(assignment_or_quiz, user)
 
     result_assignment_or_quiz = self.assignment_with_overrides(assignment_or_quiz, overrides)
@@ -85,7 +91,7 @@ def self.overrides_for_assignment_and_user(assignment_or_quiz, user)
       # NOT exclude deleted overrides, yet
       key = assignment_or_quiz.is_a?(Quiz) ? :quiz_id : :assignment_id
       adhoc_membership = AssignmentOverrideStudent.where(key => assignment_or_quiz, :user_id => user).first
-      
+
       overrides << adhoc_membership.assignment_override if adhoc_membership
 
       if assignment_or_quiz.is_a?(Assignment) && assignment_or_quiz.group_category && group = user.current_groups.where(:group_category_id => assignment_or_quiz.group_category_id).first
@@ -143,35 +149,45 @@ def self.overrides_for_assignment_and_user(assignment_or_quiz, user)
     end
   end
 
+  # really takes an assignment or quiz but who wants to type out
+  # assignment_or_quiz all the time?
+  def self.setup_overridden_clone(assignment, overrides = [])
+    clone = assignment.clone
+
+    # ActiveRecord::Base#clone nils out the primary key; put it back
+    clone.id = assignment.id
+    self.copy_preloaded_associations_to_clone(assignment,
+                                              clone)
+    yield(clone) if block_given?
+
+    clone.applied_overrides = overrides
+    clone.without_overrides = assignment
+    clone.overridden = true
+    clone.readonly!
+
+    new_record = assignment.instance_variable_get(:@new_record)
+    clone.instance_variable_set(:@new_record, new_record)
+
+    clone
+  end
+
   # apply the overrides calculated by collapsed_overrides to a clone of the
   # assignment or quiz which can then be used in place of the original object.
   # the clone is marked readonly to prevent saving
   def self.assignment_with_overrides(assignment_or_quiz, overrides)
     unoverridden_assignment_or_quiz = assignment_or_quiz.without_overrides
-    # ActiveRecord::Base#clone nils out the primary key; put it back
-    cloned_assignment_or_quiz = unoverridden_assignment_or_quiz.clone
-    cloned_assignment_or_quiz.id = unoverridden_assignment_or_quiz.id
-    self.copy_preloaded_associations_to_clone(assignment_or_quiz,
-                                              cloned_assignment_or_quiz)
-
-    # update attributes with overrides
-    if overrides
-      self.collapsed_overrides(unoverridden_assignment_or_quiz, overrides).each do |field,value|
-        # for any times in the value set, bring them back from raw UTC into the
-        # current Time.zone before placing them in the assignment
-        value = value.in_time_zone if value && value.respond_to?(:in_time_zone) && !value.is_a?(Date)
-        cloned_assignment_or_quiz.write_attribute(field, value)
+
+    self.setup_overridden_clone(unoverridden_assignment_or_quiz,
+                                overrides) do |cloned_assignment_or_quiz|
+      if overrides
+        self.collapsed_overrides(unoverridden_assignment_or_quiz, overrides).each do |field,value|
+          # for any times in the value set, bring them back from raw UTC into the
+          # current Time.zone before placing them in the assignment
+          value = value.in_time_zone if value && value.respond_to?(:in_time_zone) && !value.is_a?(Date)
+          cloned_assignment_or_quiz.write_attribute(field, value)
+        end
       end
     end
-    cloned_assignment_or_quiz.applied_overrides = overrides
-    cloned_assignment_or_quiz.without_overrides = unoverridden_assignment_or_quiz
-    cloned_assignment_or_quiz.overridden = true
-    cloned_assignment_or_quiz.readonly!
-
-    new_record = unoverridden_assignment_or_quiz.instance_variable_get(:@new_record)
-    cloned_assignment_or_quiz.instance_variable_set(:@new_record, new_record)
-    
-    cloned_assignment_or_quiz
   end
 
   def self.copy_preloaded_associations_to_clone(orig, clone)

lib/dates_overridable.rb

@@ -1,5 +1,6 @@
 module DatesOverridable
-  attr_accessor :applied_overrides, :overridden_for_user, :overridden
+  attr_accessor :applied_overrides, :overridden_for_user, :overridden,
+    :has_no_overrides
   attr_writer :without_overrides
 
   def self.included(base)

spec/lib/assignment_override_applicator_spec.rb

@@ -830,7 +830,28 @@ def setup_overridden_assignments(section_due_at, assignment_due_at)
       @unoverridden_assignment.overridden_for_user.should == nil
     end
   end
-  
+
+  describe "Overridable#has_no_overrides" do
+    before do
+      student_in_course
+      @assignment = assignment_model(:course => @course,
+                                     :due_at => 1.week.from_now)
+      o = assignment_override_model(:assignment => @assignment,
+                                    :due_at => 1.week.ago)
+      o.assignment_override_students.create! user: @student
+    end
+
+    it "makes assignment_overridden_for lie!" do
+      truly_overridden_assignment = AssignmentOverrideApplicator.assignment_overridden_for(@assignment, @student)
+
+      @assignment.has_no_overrides = true
+      fake_overridden_assignment = AssignmentOverrideApplicator.assignment_overridden_for(@assignment, @student)
+      fake_overridden_assignment.overridden.should be_true
+      fake_overridden_assignment.due_at.should_not == truly_overridden_assignment.due_at
+      fake_overridden_assignment.due_at.should == @assignment.due_at
+    end
+  end
+
   it "should use the full stack" do
     student_in_course
     original_due_at = 3.days.from_now