don't use preload_associations

it's a shim of the rails 2 variety, and breaks in rails 4 in the
common case because the options became a scope

Change-Id: I712a8fed35ee0a9747a13c1495f7d51b8dac6823
Reviewed-on: https://gerrit.instructure.com/41716
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Nick Cloward <ncloward@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>

app/controllers/accounts_controller.rb

@@ -116,7 +116,7 @@ class AccountsController < ApplicationController
         else
           @accounts = []
         end
-        Account.send(:preload_associations, @accounts, [:root_account])
+        ActiveRecord::Associations::Preloader.new(@accounts, :root_account).run
         render :json => @accounts.map { |a| account_json(a, @current_user, session, params[:includes] || []) }
       end
     end
@@ -135,7 +135,7 @@ class AccountsController < ApplicationController
         js_env(:ACCOUNT_COURSES_PATH => account_courses_path(@account, :format => :json))
         load_course_right_side
         @courses = @account.fast_all_courses(:term => @term, :limit => @maximum_courses_im_gonna_show, :hide_enrollmentless_courses => @hide_enrollmentless_courses)
-        Course.send(:preload_associations, @courses, :enrollment_term)
+        ActiveRecord::Associations::Preloader.new(@courses, :enrollment_term).run
         build_course_stats
       end
       format.json { render :json => account_json(@account, @current_user, session, params[:includes] || []) }
@@ -178,7 +178,7 @@ class AccountsController < ApplicationController
     @accounts = Api.paginate(@accounts, self, api_v1_sub_accounts_url,
                              :total_entries => recursive ? nil : @accounts.count)
 
-    Account.send(:preload_associations, @accounts, [:root_account, :parent_account])
+    ActiveRecord::Associations::Preloader.new(@accounts, [:root_account, :parent_account]).run
     render :json => @accounts.map { |a| account_json(a, @current_user, session, []) }
   end
 
@@ -282,7 +282,7 @@ class AccountsController < ApplicationController
 
     @courses = Api.paginate(@courses, self, api_v1_account_courses_url)
 
-    Course.send(:preload_associations, @courses, [:account, :root_account])
+    ActiveRecord::Associations::Preloader.new(@courses, [:account, :root_account])
     render :json => @courses.map { |c| course_json(c, @current_user, session, [], nil) }
   end
 
@@ -486,7 +486,7 @@ class AccountsController < ApplicationController
       end
       load_course_right_side
       @account_users = @account.account_users
-      AccountUser.send(:preload_associations, @account_users, user: :communication_channels)
+      ActiveRecord::Associations::Preloader.new(@account_users, user: :communication_channels).run
       order_hash = {}
       @account.available_account_roles.each_with_index do |type, idx|
         order_hash[type] = idx

app/controllers/appointment_groups_controller.rb

@@ -257,7 +257,7 @@ class AppointmentGroupsController < ApplicationController
       api_v1_appointment_groups_url(:scope => params[:scope])
     )
     if params[:include]
-      AppointmentGroup.send(:preload_associations, groups,
+      ActiveRecord::Associations::Preloader.new(groups,
                             [{:appointments =>
                                [:parent_event,
                                 {:context =>
@@ -270,7 +270,7 @@ class AppointmentGroupsController < ApplicationController
                                      [:parent_event,
                                       :context]}]}]},
                              {:appointment_group_contexts => :context},
-                             :appointment_group_sub_contexts])
+                             :appointment_group_sub_contexts]).run
     end
     render :json => groups.map{ |group| appointment_group_json(group, @current_user, session, :include => params[:include]) } 
   end

app/controllers/assignment_groups_controller.rb

@@ -118,7 +118,7 @@ class AssignmentGroupsController < ApplicationController
         # aliased table names the conditons on has_many :context_module_tags will break
         if params[:include].include? "module_ids"
           module_includes = [:context_module_tags,{:discussion_topic => :context_module_tags},{:quiz => :context_module_tags}]
-          Assignment.send(:preload_associations, all_visible_assignments, module_includes)
+          ActiveRecord::Associations::Preloader.new(all_visible_assignments, module_includes).run
         end
 
         assignment_descriptions = all_visible_assignments.map(&:description)

app/controllers/assignments_api_controller.rb

@@ -548,7 +548,7 @@ class AssignmentsApiController < ApplicationController
       override_param = params[:override_assignment_dates] || true
       override_dates = value_to_boolean(override_param)
       if override_dates
-        Assignment.send(:preload_associations, assignments, :assignment_overrides)
+        ActiveRecord::Associations::Preloader.new(assignments, :assignment_overrides).run
         assignments.select{ |a| a.assignment_overrides.size == 0 }.
           each { |a| a.has_no_overrides = true }
       end

app/controllers/calendar_events_api_controller.rb

@@ -304,7 +304,7 @@ class CalendarEventsApiController < ApplicationController
 
     scope = @type == :assignment ? assignment_scope : calendar_event_scope
     events = Api.paginate(scope, self, api_v1_calendar_events_url)
-    CalendarEvent.send(:preload_associations, events, :child_events) if @type == :event
+    ActiveRecord::Associations::Preloader.new(events, :child_events).run if @type == :event
     events = apply_assignment_overrides(events) if @type == :assignment
 
     if @errors.empty?

app/controllers/context_module_items_api_controller.rb

@@ -223,7 +223,7 @@ class ContextModuleItemsApiController < ApplicationController
   def index
     if authorized_action(@context, @current_user, :read)
       mod = @context.modules_visible_to(@student || @current_user).find(params[:module_id])
-      ContextModule.send(:preload_associations, mod, {:content_tags => :content})
+      ActiveRecord::Associations::Preloader.new(mod, content_tags: :content).run
       route = polymorphic_url([:api_v1, @context, mod, :items])
       scope = mod.content_tags_visible_to(@student || @current_user)
       scope = ContentTag.search_by_attribute(scope, :title, params[:search_term])

app/controllers/context_modules_api_controller.rb

@@ -358,7 +358,7 @@ class ContextModulesApiController < ApplicationController
       scope = ContextModule.search_by_attribute(scope, :name, params[:search_term]) unless includes.include?('items')
       modules = Api.paginate(scope, self, route)
 
-      ContextModule.send(:preload_associations, modules, {:content_tags => :content}) if includes.include?('items')
+      ActiveRecord::Associations::Preloader.new(modules, content_tags: :content) if includes.include?('items')
 
       if @student
         modules_and_progressions = modules.map { |m| [m, m.evaluate_for(@student)] }
@@ -418,7 +418,7 @@ class ContextModulesApiController < ApplicationController
     if authorized_action(@context, @current_user, :read)
       mod = @context.modules_visible_to(@student || @current_user).find(params[:id])
       includes = Array(params[:include])
-      ContextModule.send(:preload_associations, mod, {:content_tags => :content}) if includes.include?('items')
+      ActiveRecord::Associations::Preloader.new(mod, content_tags: :content).run if includes.include?('items')
       prog = @student ? mod.evaluate_for(@student) : nil
       render :json => module_json(mod, @student || @current_user, session, prog, includes)
     end

app/controllers/context_modules_controller.rb

@@ -40,7 +40,7 @@ class ContextModulesController < ApplicationController
       load_modules
       if @context.grants_right?(@current_user, session, :participate_as_student)
         return unless tab_enabled?(@context.class::TAB_MODULES)
-        ContextModule.send(:preload_associations, @modules, [:content_tags])
+        ActiveRecord::Associations::Preloader.new(@modules, :content_tags).run
         @modules.each{|m| m.evaluate_for(@current_user) }
         session[:module_progressions_initialized] = true
       end

app/controllers/conversations_controller.rb

@@ -502,7 +502,7 @@ class ConversationsController < ApplicationController
     messages = nil
     Shackles.activate(:slave) do
       messages = @conversation.messages
-      ConversationMessage.send(:preload_associations, messages, :asset)
+      ActiveRecord::Associations::Preloader.new(messages, :asset).run
     end
 
     render :json => conversation_json(@conversation,

app/controllers/courses_controller.rb

@@ -701,9 +701,10 @@ class CoursesController < ApplicationController
       if includes.include?('enrollments')
         # not_ended_enrollments for enrollment_json
         # enrollments course for has_grade_permissions?
-        User.send(:preload_associations, users, { :not_ended_enrollments => :course },
+        ActiveRecord::Associations::Preloader.new(users,
+                                                  { :not_ended_enrollments => :course },
                   :conditions => ['enrollments.course_id = ?', @context.id],
-                  :shard => @context.shard)
+                  :shard => @context.shard).run
       end
       render :json => users.map { |u|
         enrollments = u.not_ended_enrollments if includes.include?('enrollments')
@@ -751,9 +752,10 @@ class CoursesController < ApplicationController
       if includes.include?('enrollments')
         # not_ended_enrollments for enrollment_json
         # enrollments course for has_grade_permissions?
-        User.send(:preload_associations, users, {:not_ended_enrollments => :course},
+        ActiveRecord::Associations::Preloader.new(users,
+                                                  {:not_ended_enrollments => :course},
                   :conditions => ['enrollments.course_id = ?', @context.id],
-                  :shard => @context.shard)
+                  :shard => @context.shard).run
       end
       user = users.first or raise ActiveRecord::RecordNotFound
       enrollments = user.not_ended_enrollments if includes.include?('enrollments')
@@ -1522,7 +1524,7 @@ class CoursesController < ApplicationController
                           :search_method => @context.user_list_search_mode_for(@current_user),
                           :initial_type => params[:enrollment_type])
       if !@context.concluded? && (@enrollments = EnrollmentsFromUserList.process(list, @context, enrollment_options))
-        Enrollment.send(:preload_associations, @enrollments, [:course_section, {:user => [:communication_channel, :pseudonym]}])
+        ActiveRecord::Associations::Preloader.new(@enrollments, [:course_section, {:user => [:communication_channel, :pseudonym]}]).run
         json = @enrollments.map { |e|
           { 'enrollment' =>
             { 'associated_user_id' => e.associated_user_id,

app/controllers/enrollments_api_controller.rb

@@ -243,7 +243,7 @@ class EnrollmentsApiController < ApplicationController
       enrollments,
       self, send("api_v1_#{endpoint_scope}_enrollments_url"))
 
-    Enrollment.send(:preload_associations, enrollments, [:user, :course, :course_section])
+    ActiveRecord::Associations::Preloader.new(enrollments, [:user, :course, :course_section]).run
     includes = [:user] + Array(params[:include])
 
     user_json_preloads(enrollments.map(&:user))

app/controllers/gradebook_history_api_controller.rb

@@ -305,7 +305,7 @@
     # paginate the indexed scope and then convert to actual Version records
     path = api_v1_gradebook_history_feed_url(@context, params)
     indexed_versions = Api.paginate(indexed_versions, self, path)
-    SubmissionVersion.send(:preload_associations, indexed_versions, :version)
+    ActiveRecord::Associations::Preloader.new(indexed_versions, :version).run
     versions = indexed_versions.map(&:version)
 
     # render them

app/controllers/outcome_groups_api_controller.rb

@@ -320,7 +320,7 @@ class OutcomeGroupsApiController < ApplicationController
       end
 
       # preload the links' outcomes' contexts.
-      ContentTag.send(:preload_associations, @links, :learning_outcome_content => :context)
+      ActiveRecord::Associations::Preloader.new(@links, :learning_outcome_content => :context).run
 
       # render to json and serve
       render :json => @links.map{ |link| outcome_link_json(link, @current_user, session) }

app/controllers/sub_accounts_controller.rb

@@ -88,7 +88,7 @@ class SubAccountsController < ApplicationController
   
   def show
     @sub_account = subaccount_or_self(params[:id])
-    Account.send(:preload_associations, @sub_account, [{:sub_accounts => [:parent_account, :root_account]}, {:courses => [:account, :root_account]}])
+    ActiveRecord::Associations::Preloader.new(@sub_account, [{:sub_accounts => [:parent_account, :root_account]}, {:courses => [:account, :root_account]}]).run
     render :json => @sub_account.as_json(:include => [:sub_accounts, :courses], :methods => [:course_count, :sub_account_count])
   end
   

app/controllers/submissions_api_controller.rb

@@ -506,7 +506,7 @@ class SubmissionsApiController < ApplicationController
   def bulk_load_attachments_and_previews(submissions)
     Submission.bulk_load_versioned_attachments(submissions)
     attachments = submissions.flat_map &:versioned_attachments
-    Attachment.send :preload_associations, attachments,
-      [:canvadoc, :crocodoc_document]
+    ActiveRecord::Associations::Preloader.new(attachments,
+      [:canvadoc, :crocodoc_document]).run
   end
 end

app/controllers/user_notes_controller.rb

@@ -44,7 +44,7 @@ class UserNotesController < ApplicationController
       @users = @users.select("name, users.id, last_user_note").order("last_user_note").order_by_sortable_name
       @users = @users.paginate(:page => params[:page], :per_page => 20, :total_entries=>count)
       # rails gets confused by :include => :courses, because has_current_student_enrollments above references courses in a subquery
-      User.send(:preload_associations, @users, :courses)
+      ActiveRecord::Associations::Preloader.new(@users, :courses).run
     end
   end
 

app/controllers/users_controller.rb

@@ -132,7 +132,7 @@ class UsersController < ApplicationController
         return
       end
 
-      Enrollment.send(:preload_associations, @observed_enrollments, :course)
+      ActiveRecord::Associations::Preloader.new(@observed_enrollments, :course).run
     end
   end
 

app/helpers/search_helper.rb

@@ -66,8 +66,8 @@ module SearchHelper
       end
 
       add_groups = lambda do |groups|
-        Group.send(:preload_associations, groups, :group_category)
-        Group.send(:preload_associations, groups, :group_memberships, conditions: { group_memberships: { user_id: @current_user }})
+        ActiveRecord::Associations::Preloader.new(groups, :group_category).run
+        ActiveRecord::Associations::Preloader.new(groups, :group_memberships, conditions: { group_memberships: { user_id: @current_user }}).run
         groups.each do |group|
           group.can_participate = true
           contexts[:groups][group.id] = {

app/models/account_notification.rb

@@ -31,7 +31,7 @@ class AccountNotification < ActiveRecord::Base
 
   def self.for_user_and_account(user, account)
     current = self.for_account(account)
-    preload_associations(current, [:account, :account_notification_roles])
+    ActiveRecord::Associations::Preloader.new(current, [:account, :account_notification_roles]).run
     user_role_types = {}
 
     current.select! do |announcement|

app/models/conversation.rb

@@ -468,7 +468,7 @@ class Conversation < ActiveRecord::Base
   end
 
   def subscribed_participants
-    ConversationParticipant.send(:preload_associations, conversation_participants, :user) unless ModelCache[:users]
+    ActiveRecord::Associations::Preloader.new(conversation_participants, :user).run unless ModelCache[:users]
     conversation_participants.select(&:subscribed?).map(&:user).compact
   end
 

app/models/course.rb

@@ -414,7 +414,7 @@ class Course < ActiveRecord::Base
 
       if courses_or_course_ids.first.is_a? Course
         courses = courses_or_course_ids
-        Course.send(:preload_associations, courses, :course_sections => :nonxlist_course)
+        ActiveRecord::Associations::Preloader.new(courses, :course_sections => :nonxlist_course).run
         course_ids = courses.map(&:id)
       else
         course_ids = courses_or_course_ids

app/models/stream_item.rb

@@ -294,7 +294,7 @@ class StreamItem < ActiveRecord::Base
   def self.prepare_object_for_unread(object)
     case object
       when DiscussionTopic
-      DiscussionTopic.send(:preload_associations, object, :discussion_topic_participants)
+        ActiveRecord::Associations::Preloader.new(object, :discussion_topic_participants).run
     end
   end
 

app/models/submission_comment.rb

@@ -190,9 +190,9 @@ class SubmissionComment < ActiveRecord::Base
   end
 
   def self.preload_attachments(comments)
-    SubmissionComment.send :preload_associations, comments, [:associated_attachments, :submission]
+    ActiveRecord::Associations::Preloader.new(comments, [:associated_attachments, :submission]).run
     submissions = comments.map(&:submission).uniq
-    Submission.send :preload_associations, submissions, :assignment => :attachments
+    ActiveRecord::Associations::Preloader.new(submissions, :assignment => :attachments).run
   end
 
   def update_submission

app/models/user.rb

@@ -1421,7 +1421,7 @@ class User < ActiveRecord::Base
               expecting_submission.
               not_ignored_by(self, 'grading').
               need_grading_info(limit)
-            Assignment.send :preload_associations, as, :context
+            ActiveRecord::Associations::Preloader.new(as, :context).run
             as.reject{|a| Assignments::NeedsGradingCountQuery.new(a, self).count == 0 }
           end
           # outer limit, since there could be limit * n_shards results
@@ -1614,7 +1614,7 @@ class User < ActiveRecord::Base
         end
         pending_enrollments = temporary_invitations
         unless pending_enrollments.empty?
-          Enrollment.send(:preload_associations, pending_enrollments, :course)
+          ActiveRecord::Associations::Preloader.new(pending_enrollments, :course).run
           res.concat(pending_enrollments.map { |e| c = e.course; c.write_attribute(:primary_enrollment, e.type); c.write_attribute(:primary_enrollment_rank, e.rank_sortable.to_s); c.write_attribute(:primary_enrollment_state, e.workflow_state); c.write_attribute(:invitation, e.uuid); c })
           res.uniq!
         end
@@ -1653,7 +1653,7 @@ class User < ActiveRecord::Base
       end
     end + temporary_invitations
     if opts[:preload_courses]
-      Enrollment.send(:preload_associations, enrollments, [:course])
+      ActiveRecord::Associations::Preloader.new(enrollments, :course).run
     end
     enrollments
   end
@@ -1727,7 +1727,7 @@ class User < ActiveRecord::Base
           submissions = submissions.uniq
           submissions.first(opts[:limit])
 
-          Submission.send(:preload_associations, submissions, [:assignment, :user, :submission_comments])
+          ActiveRecord::Associations::Preloader.new(submissions, [:assignment, :user, :submission_comments]).run
           submissions
         end
       end

app/views/context_modules/_content.html.erb

@@ -57,7 +57,7 @@ TEXT
   <div id="context_modules" tabindex="0" aria-label="<%= t('headings.course_modules', %{Course Modules}) %>" class="<%= 'editable' if can_do(@context, @current_user, :manage_content) %>">
     <% editable = can_do(@context, @current_user, :manage_content) %>
     <% cache([@context.cache_key, editable, 'all_context_modules_6', collection_cache_key(@modules)].join('/')) do %>
-      <% ContextModule.send(:preload_associations, @modules, :content_tags => :content) %>
+      <% ActiveRecord::Associations::Preloader.new(@modules, :content_tags => :content).run %>
       <% @modules.each do |m| %>
         <%= render :partial => 'context_modules/context_module', :object => m, :locals => {:editable => editable } %>
       <% end %>

app/views/context_modules/_content_next.html.erb

@@ -232,7 +232,7 @@ TEXT
     <% cache_key = cache_key_items.join('/') %>
     <% cache_key = add_menu_tools_to_cache_key(cache_key) %>
     <% cache(cache_key) do %>
-      <% ContextModule.send(:preload_associations, @modules, :content_tags => :content) %>
+      <% ActiveRecord::Associations::Preloader.new(@modules, :content_tags => :content).run %>
       <% @modules.each do |m| %>
         <%= render :partial => 'context_modules/context_module_next', :object => m, :locals => {:editable => editable } %>
       <% end %>

config/initializers/active_record.rb

@@ -1,14 +1,6 @@
 require 'active_support/callbacks/suspension'
 
 class ActiveRecord::Base
-  # XXX: Rails3 There are lots of issues with these patches in Rails3 still
-
-  class << self
-    def preload_associations(records, associations, preload_options={})
-      ActiveRecord::Associations::Preloader.new(records, associations, preload_options).run
-    end
-  end
-
   def write_attribute(*args)
     value = super
     value.is_a?(ActiveRecord::AttributeMethods::Serialization::Attribute) ? value.value : value

lib/api/v1/assignment_override.rb

@@ -43,7 +43,7 @@ module Api::V1::AssignmentOverride
   def assignment_override_collection(assignment, include_students=false)
     overrides = AssignmentOverrideApplicator.overrides_for_assignment_and_user(assignment, @current_user)
     if include_students
-      AssignmentOverride.send(:preload_associations, overrides, :assignment_override_students)
+      ActiveRecord::Associations::Preloader.new(overrides, :assignment_override_students).run
     end
     overrides
   end

lib/api/v1/calendar_event.rb

@@ -105,7 +105,7 @@ module Api::V1::CalendarEvent
         events = can_read_child_events ? event.child_events.to_a : event.child_events_for(participant)
 
         # do some preloads
-        CalendarEvent.send(:preload_associations, events, :context)
+        ActiveRecord::Associations::Preloader.new(events, :context).run
         if events.first.context.is_a?(User) && user_json_is_admin?(@context, user)
           user_json_preloads(events.map(&:context))
         end
@@ -167,7 +167,7 @@ module Api::V1::CalendarEvent
     if include.include?('appointments')
       if include.include?('child_events')
         all_child_events = group.appointments.map(&:child_events).flatten
-        CalendarEvent.send(:preload_associations, all_child_events, :context)
+        ActiveRecord::Associations::Preloader.new(all_child_events, :context).run
         user_json_preloads(all_child_events.map(&:context)) if !all_child_events.empty? && all_child_events.first.context.is_a?(User) && user_json_is_admin?(@context, user)
       end
       hash['appointments'] = group.appointments.map { |event| calendar_event_json(event, user, session,

lib/api/v1/gradebook_history.rb

@@ -50,11 +50,11 @@ module Api::V1
     def versions_json(course, versions, api_context, opts={})
       # preload for efficiency
       unless opts[:submission]
-        ::Version.send(:preload_associations, versions, :versionable)
+        ActiveRecord::Associations::Preloader.new(versions, :versionable).run
         submissions = versions.map(&:versionable)
-        ::Submission.send(:preload_associations, submissions, :assignment) unless opts[:assignment]
-        ::Submission.send(:preload_associations, submissions, :user) unless opts[:student]
-        ::Submission.send(:preload_associations, submissions, :grader)
+        ActiveRecord::Associations::Preloader.new(submissions, :assignment).run unless opts[:assignment]
+        ActiveRecord::Associations::Preloader.new(submissions, :user).run unless opts[:student]
+        ActiveRecord::Associations::Preloader.new(submissions, :grader).run
       end
 
       versions.map do |version|

lib/api/v1/user.rb

@@ -29,10 +29,10 @@ module Api::V1::User
   def user_json_preloads(users, preload_email=false)
     # pseudonyms for User#sis_pseudoym_for and User#find_pseudonym_for_account
     # pseudonyms account for Pseudonym#works_for_account?
-    User.send(:preload_associations, users, [{ :pseudonyms => :account }]) if user_json_is_admin?
+    ActiveRecord::Associations::Preloader.new(users, pseudonyms: :account).run if user_json_is_admin?
     if preload_email && (no_email_users = users.reject(&:email_cached?)).present?
       # communication_channels for User#email if it is not cached
-      User.send(:preload_associations, no_email_users, :communication_channels)
+      ActiveRecord::Associations::Preloader.new(no_email_users, :communication_channels).run
     end
   end
 

lib/canvas/builders/enrollment_date_builder.rb

@@ -31,12 +31,12 @@ class EnrollmentDateBuilder
   def self.preload(enrollments)
     return if enrollments.empty?
     courses_loaded = enrollments.first.association(:course).loaded?
-    Enrollment.send(:preload_associations, enrollments, :course) unless courses_loaded
+    ActiveRecord::Associations::Preloader.new(enrollments, :course).run unless courses_loaded
 
     to_preload = enrollments.reject { |e| fetch(e) }
     return if to_preload.empty?
-    Enrollment.send(:preload_associations, to_preload, :course_section)
-    Course.send(:preload_associations, to_preload.map(&:course).uniq, :enrollment_term)
+    ActiveRecord::Associations::Preloader.new(to_preload, :course_section).run
+    ActiveRecord::Associations::Preloader.new(to_preload.map(&:course).uniq, :enrollment_term).run
     to_preload.each { |e| build(e) }
   end
 

spec/models/context_module_spec.rb

@@ -905,7 +905,7 @@ describe ContextModule do
       # if tags are preloaded we shouldn't filter by a scope (as that requires re-fetching the tags)
       it "should not reload the tags if already loaded" do
         ContentTag.expects(:visible_to_students_with_da_enabled).never
-        ContextModule.send(:preload_associations, [@module], {:content_tags => :content})
+        ActiveRecord::Associations::Preloader.new(@module, content_tags: :content).run
         @module.content_tags_visible_to(@student_1)
       end
       # if tags are not preloaded we should filter by a scope (as will be quicker than filtering an array)