cache doc word counts

app/jobs/save_document_revision_job.rb

@@ -7,6 +7,9 @@ class SaveDocumentRevisionJob < ApplicationJob
     document = Document.find(document_id)
     return unless document.present?
 
+    # Update cached word count for the document regardless of how often this is called
+    document.update(cached_word_count: document.computed_word_count)
+
     # Make sure we're only storing revisions at least every 5 min
     latest_revision = document.document_revisions.order('created_at DESC').limit(1).first
     if latest_revision.present? && latest_revision.created_at > 5.minutes.ago

app/models/documents/document.rb

@@ -77,7 +77,10 @@ class Document < ApplicationRecord
   end
 
   def word_count
-    # TODO this should probably be cached !!
+    self.cached_word_count || self.computed_word_count
+  end
+
+  def computed_word_count
     (self.body || "").split(/\s+/).count
   end
 

db/migrate/20210701002938_add_cached_word_count_to_documents.rb

@@ -0,0 +1,5 @@
+class AddCachedWordCountToDocuments < ActiveRecord::Migration[6.0]
+  def change
+    add_column :documents, :cached_word_count, :integer
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2021_06_27_023405) do
+ActiveRecord::Schema.define(version: 2021_07_01_002938) do
 
   create_table "active_storage_attachments", force: :cascade do |t|
     t.string "name", null: false
@@ -1190,6 +1190,7 @@ ActiveRecord::Schema.define(version: 2021_06_27_023405) do
     t.boolean "favorite"
     t.text "notes_text"
     t.integer "folder_id"
+    t.integer "cached_word_count"
     t.index ["folder_id"], name: "index_documents_on_folder_id"
     t.index ["universe_id", "deleted_at"], name: "index_documents_on_universe_id_and_deleted_at"
     t.index ["universe_id"], name: "index_documents_on_universe_id"