Optimize events#show page (#572)

app/controllers/events_controller.rb

@@ -24,6 +24,8 @@ def show
       @event.talks_in_running_order.order(date: :asc)
     end
 
+    event_talks = event_talks.includes(:speakers, :parent_talk, child_talks: :speakers)
+
     if params[:q].present?
       talks = event_talks.pagy_search(params[:q])
       @pagy, @talks = pagy_meilisearch(talks, limit: 21)

app/models/event.rb

@@ -156,9 +156,11 @@ def held_in_sentence
   end
 
   def description
+    return @description if @description.present?
+
     keynotes = keynote_speakers.any? ? %(, including keynotes by #{keynote_speakers.map(&:name).to_sentence}) : ""
 
-    <<~DESCRIPTION
+    @description = <<~DESCRIPTION
       #{organisation.name} is a #{organisation.frequency} #{organisation.kind}#{held_in_sentence} and features #{talks.size} #{"talk".pluralize(talks.size)} from various speakers#{keynotes}.
     DESCRIPTION
   end
@@ -269,13 +271,13 @@ def location
   end
 
   def start_date
-    static_metadata.start_date.present? ? static_metadata.start_date : talks.minimum(:date)
+    @start_date ||= static_metadata.start_date.present? ? static_metadata.start_date : talks.minimum(:date)
   rescue => _e
     talks.minimum(:date)
   end
 
   def end_date
-    static_metadata.end_date.present? ? static_metadata.end_date : talks.maximum(:date)
+    @end_date ||= static_metadata.end_date.present? ? static_metadata.end_date : talks.maximum(:date)
   rescue => _e
     talks.maximum(:date)
   end

app/models/watched_talk.rb

@@ -15,6 +15,6 @@
 #  index_watched_talks_on_user_id              (user_id)
 #
 class WatchedTalk < ApplicationRecord
-  belongs_to :user, default: -> { Current.user }
+  belongs_to :user, default: -> { Current.user }, touch: true
   belongs_to :talk
 end

app/views/talks/show.html.erb

@@ -13,14 +13,8 @@
         <% end %>
       </div>
 
-      <% if signed_in? %>
-        <% cache_key = [@talk, Current.user, @talk.watched_talks.where(user: Current.user)] %>
-      <% else %>
-        <% cache_key = [@talk] %>
-      <% end %>
-
       <%= turbo_frame_tag "talk", target: "_top", data: {turbo_action: "advance"} do %>
-        <% cache cache_key do %>
+        <% cache [@talk, Current.user].compact do %>
           <%= render partial: "talks/talk", locals: {talk: @talk} %>
         <% end %>
       <% end %>