Use UpdateWikidataStatsTimeslice class.

app/models/course_wiki_timeslice.rb

@@ -99,6 +99,7 @@ def update_cache_from_revisions(revisions)
     update_upload_count
     update_uploads_in_use_count
     update_upload_usages_count
+    update_stats
     self.needs_update = false
     save
   end
@@ -154,4 +155,9 @@ def update_upload_usages_count
     # TODO: count only uploads updated at during the timeslice range
     self.upload_usages_count = course.uploads_in_use.sum(:usage_count)
   end
+
+  def update_stats
+    return unless wiki.project == 'wikidata'
+    self.stats = UpdateWikidataStatsTimeslice.new(course).build_stats_from_revisions(@revisions)
+  end
 end

app/services/update_course_stats_timeslice.rb

@@ -32,7 +32,7 @@ def initialize(course)
     update_article_status if should_update_article_status?
     update_average_pageviews
     update_caches
-    # update_wikidata_stats if wikidata
+    update_wikidata_stats if wikidata
     # This needs to happen after `update_caches` because it relies on ArticlesCourses#new_article
     # to calculate new article stats for each namespace.
     update_wiki_namespace_stats
@@ -85,7 +85,10 @@ def update_caches
   end
 
   def update_wikidata_stats
-    UpdateWikidataStatsWorker.new.perform(@course)
+    wikidata = Wiki.get_or_create(language: nil, project: 'wikidata')
+    timeslices = CourseWikiTimeslice.for_course_and_wiki(@course, wikidata)
+    stats = timeslices.pluck(:stats)
+    UpdateWikidataStatsTimeslice.new(@course).update_wikidata_statistics(stats)
     @debugger.log_update_progress :wikidata_stats_updated
   end
 

app/services/update_course_wiki_timeslices.rb

@@ -17,6 +17,7 @@ def initialize(course)
     @course = course
     @timeslice_manager = TimesliceManager.new(@course)
     @debugger = UpdateDebugger.new(@course)
+    @wikidata_stats_updater = UpdateWikidataStatsTimeslice.new(@course) if wikidata
   end
 
   def run(all_time:)
@@ -88,6 +89,13 @@ def fetch_data(wiki, timeslice_start, timeslice_end)
                                                       timeslice_start.strftime('%Y%m%d%H%M%S'),
                                                       timeslice_end.strftime('%Y%m%d%H%M%S'),
                                                       update_service: self)
+
+    # Only for wikidata project, fetch wikidata stats
+    if wiki.project == 'wikidata' && @revisions.present?
+      wikidata_revisions = @revisions[wiki][:revisions]
+      @revisions[wiki][:revisions] =
+        @wikidata_stats_updater.update_revisions_with_stats(wikidata_revisions)
+    end
     # TODO: replace the logic on ArticlesCourses.update_from_course to remove all
     # the ArticlesCourses that do not correspond to course revisions.
     # That may happen if the course dates changed, so some revisions are no
@@ -144,6 +152,10 @@ def update_course_user_wiki_timeslices_for_wiki(wiki, revisions)
     end
   end
 
+  def wikidata
+    @course.wikis.find { |wiki| wiki.project == 'wikidata' }
+  end
+
   def log_error(error)
     Sentry.capture_message "#{@course.title} update timeslices error: #{error}",
                            level: 'error'

spec/services/update_course_wiki_timeslices_spec.rb

@@ -111,6 +111,7 @@
       expect(timeslice.uploads_in_use_count).to eq(0)
       expect(timeslice.upload_usages_count).to eq(0)
       expect(timeslice.last_mw_rev_datetime).to eq('20181129180841'.to_datetime)
+      expect(timeslice.stats).to be_empty
 
       # For wikidata
       timeslice = course.course_wiki_timeslices.where(wiki: wikidata,
@@ -122,6 +123,7 @@
       expect(timeslice.uploads_in_use_count).to eq(0)
       expect(timeslice.upload_usages_count).to eq(0)
       expect(timeslice.last_mw_rev_datetime).to eq('20181124045740'.to_datetime)
+      expect(timeslice.stats['references removed']).to eq(2)
     end
 
     it 'rolls back the updates if something goes wrong' do