Alter previous method on all versions models

This is to prevent redoing the same SQL query which wasn't being cached.

app/models/artist_commentary_version.rb

@@ -7,4 +7,11 @@ class ArtistCommentaryVersion < ApplicationRecord
     q = q.search_attributes(params, :post, :updater, :original_title, :original_description, :translated_title, :translated_description)
     q.apply_default_order(params)
   end
+
+  def previous
+    @previous ||= begin
+      ArtistCommentaryVersion.where("post_id = ? and updated_at < ?", post_id, updated_at).order("updated_at desc").limit(1).to_a
+    end
+    @previous.first
+  end
 end

app/models/artist_version.rb

@@ -24,6 +24,9 @@ class ArtistVersion < ApplicationRecord
   extend SearchMethods
 
   def previous
-    ArtistVersion.where("artist_id = ? and created_at < ?", artist_id, created_at).order("created_at desc").first
+    @previous ||= begin
+      ArtistVersion.where("artist_id = ? and created_at < ?", artist_id, created_at).order("created_at desc").limit(1).to_a
+    end
+    @previous.first
   end
 end

app/models/note_version.rb

@@ -13,6 +13,9 @@ class NoteVersion < ApplicationRecord
   end
 
   def previous
-    NoteVersion.where("note_id = ? and updated_at < ?", note_id, updated_at).order("updated_at desc").first
+    @previous ||= begin
+      NoteVersion.where("note_id = ? and updated_at < ?", note_id, updated_at).order("updated_at desc").limit(1).to_a
+    end
+    @previous.first
   end
 end

app/models/pool_archive.rb

@@ -108,7 +108,10 @@ class PoolArchive < ApplicationRecord
   end
 
   def previous
-    PoolArchive.where("pool_id = ? and version < ?", pool_id, version).order("version desc").first
+    @previous ||= begin
+      PoolArchive.where("pool_id = ? and version < ?", pool_id, version).order("version desc").limit(1).to_a
+    end
+    @previous.first
   end
 
   def pretty_name

app/models/post_archive.rb

@@ -92,13 +92,16 @@ class PostArchive < ApplicationRecord
   end
 
   def previous
-    # HACK: if all the post versions for this post have already been preloaded,
-    # we can use that to avoid a SQL query.
-    if association(:post).loaded? && post && post.association(:versions).loaded?
-      post.versions.sort_by(&:version).reverse.find { |v| v.version < version }
-    else
-      PostArchive.where("post_id = ? and version < ?", post_id, version).order("version desc").first
+    @previous ||= begin
+      # HACK: if all the post versions for this post have already been preloaded,
+      # we can use that to avoid a SQL query.
+      if association(:post).loaded? && post && post.association(:versions).loaded?
+        ver = [post.versions.sort_by(&:version).reverse.find { |v| v.version < version }]
+      else
+        ver = PostArchive.where("post_id = ? and version < ?", post_id, version).order("version desc").limit(1).to_a
+      end
     end
+    @previous.first
   end
 
   def visible?

app/models/wiki_page_version.rb

@@ -23,7 +23,10 @@ class WikiPageVersion < ApplicationRecord
   end
 
   def previous
-    WikiPageVersion.where("wiki_page_id = ? and id < ?", wiki_page_id, id).order("id desc").first
+    @previous ||= begin
+      WikiPageVersion.where("wiki_page_id = ? and id < ?", wiki_page_id, id).order("id desc").limit(1).to_a
+    end
+    @previous.first
   end
 
   def category_name