FIX: render canonical URLs

app/controllers/topics_controller.rb

@@ -83,9 +83,10 @@ class TopicsController < ApplicationController
       response.headers['X-Robots-Tag'] = 'noindex'
     end
 
+    canonical_url UrlHelper.absolute_without_cdn("#{Discourse.base_uri}#{@topic_view.canonical_path}")
+
     perform_show_response
 
-    canonical_url UrlHelper.absolute_without_cdn("#{Discourse.base_uri}#{@topic_view.canonical_path}")
   rescue Discourse::InvalidAccess => ex
 
     if current_user

spec/controllers/topics_controller_spec.rb

@@ -521,6 +521,17 @@ describe TopicsController do
     end
   end
 
+  describe 'show full render' do
+    render_views
+
+    it 'correctly renders canoicals' do
+      topic = Fabricate(:post).topic
+      get :show, topic_id: topic.id, slug: topic.slug
+      expect(response).to be_success
+      expect(css_select("link[rel=canonical]").length).to eq(1)
+    end
+  end
+
   describe 'show' do
 
     let(:topic) { Fabricate(:post).topic }