FIX: Create readonly functions during backup

Temporarily recreate already dropped functions in the discourse_functions schema in order to allow restoring of backups which still reference dropped functions.

db/post_migrate/20180917024729_remove_superfluous_columns.rb

@@ -4,24 +4,23 @@ require 'migration/column_dropper'
 require 'badge_posts_view_manager'
 
 class RemoveSuperfluousColumns < ActiveRecord::Migration[5.2]
-  def up
-    {
-      user_profiles: %i{
+  DROPPED_COLUMNS ||= {
+    user_profiles: %i{
         card_image_badge_id
       },
-      categories: %i{
+    categories: %i{
         logo_url
         background_url
         suppress_from_homepage
       },
-      groups: %i{
+    groups: %i{
         visible
         public
         alias_level
       },
-      theme_fields: %i{target},
-      user_stats: %i{first_topic_unread_at},
-      topics: %i{
+    theme_fields: %i{target},
+    user_stats: %i{first_topic_unread_at},
+    topics: %i{
         auto_close_at
         auto_close_user_id
         auto_close_started_at
@@ -35,7 +34,7 @@ class RemoveSuperfluousColumns < ActiveRecord::Migration[5.2]
         last_unread_at
         vote_count
       },
-      users: %i{
+    users: %i{
         email
         email_always
         mailing_list_mode
@@ -58,23 +57,27 @@ class RemoveSuperfluousColumns < ActiveRecord::Migration[5.2]
         silenced
         trust_level_locked
       },
-      user_auth_tokens: %i{legacy},
-      user_options: %i{theme_key},
-      themes: %i{key},
-      email_logs: %i{
+    user_auth_tokens: %i{legacy},
+    user_options: %i{theme_key},
+    themes: %i{key},
+    email_logs: %i{
         topic_id
         reply_key
         skipped
         skipped_reason
       },
-    }.each do |table, columns|
+    posts: %i{vote_count}
+  }
+
+  def up
+    BadgePostsViewManager.drop!
+
+    DROPPED_COLUMNS.each do |table, columns|
       Migration::ColumnDropper.execute_drop(table, columns)
     end
 
     DB.exec "DROP FUNCTION IF EXISTS first_unread_topic_for(int)"
 
-    BadgePostsViewManager.drop!
-    Migration::ColumnDropper.execute_drop(:posts, %i{vote_count})
     BadgePostsViewManager.create!
   end
 

db/post_migrate/20180917034056_remove_superfluous_tables.rb

@@ -3,12 +3,14 @@
 require 'migration/table_dropper'
 
 class RemoveSuperfluousTables < ActiveRecord::Migration[5.2]
-  def up
-    %i{
+  DROPPED_TABLES ||= %i{
       category_featured_users
       versions
       topic_status_updates
-    }.each do |table|
+    }
+
+  def up
+    DROPPED_TABLES.each do |table|
       Migration::TableDropper.execute_drop(table)
     end
   end

db/post_migrate/20181012123001_drop_group_locked_trust_level_from_user.rb

@@ -3,8 +3,14 @@
 require 'migration/column_dropper'
 
 class DropGroupLockedTrustLevelFromUser < ActiveRecord::Migration[5.2]
+  DROPPED_COLUMNS ||= {
+    posts: %i{group_locked_trust_level}
+  }
+
   def up
-    Migration::ColumnDropper.execute_drop(:posts, %i{group_locked_trust_level})
+    DROPPED_COLUMNS.each do |table, columns|
+      Migration::ColumnDropper.execute_drop(table, columns)
+    end
   end
 
   def down

db/post_migrate/20190103065652_remove_uploaded_meta_id_from_category.rb

@@ -3,8 +3,14 @@
 require 'migration/column_dropper'
 
 class RemoveUploadedMetaIdFromCategory < ActiveRecord::Migration[5.2]
+  DROPPED_COLUMNS ||= {
+    categories: %i{uploaded_meta_id}
+  }
+
   def up
-    Migration::ColumnDropper.execute_drop(:categories, %i{uploaded_meta_id})
+    DROPPED_COLUMNS.each do |table, columns|
+      Migration::ColumnDropper.execute_drop(table, columns)
+    end
   end
 
   def down

db/post_migrate/20190208144706_drop_unused_auth_tables_again.rb

@@ -3,11 +3,13 @@
 require 'migration/table_dropper'
 
 class DropUnusedAuthTablesAgain < ActiveRecord::Migration[5.2]
-  def up
-    %i{
+  DROPPED_TABLES ||= %i{
         facebook_user_infos
         twitter_user_infos
-      }.each do |table|
+      }
+
+  def up
+    DROPPED_TABLES.each do |table|
       Migration::TableDropper.execute_drop(table)
     end
   end

db/post_migrate/20190312194528_drop_email_user_options_columns.rb

@@ -3,14 +3,16 @@
 require 'migration/column_dropper'
 
 class DropEmailUserOptionsColumns < ActiveRecord::Migration[5.2]
-  def up
-    {
-      user_options: %i{
+  DROPPED_COLUMNS ||= {
+    user_options: %i{
         email_direct
         email_private_messages
         email_always
       },
-    }.each do |table, columns|
+  }
+
+  def up
+    DROPPED_COLUMNS.each do |table, columns|
       Migration::ColumnDropper.execute_drop(table, columns)
     end
   end

db/post_migrate/20190716124050_remove_via_email_from_invite.rb

@@ -3,8 +3,14 @@
 require 'migration/column_dropper'
 
 class RemoveViaEmailFromInvite < ActiveRecord::Migration[5.2]
+  DROPPED_COLUMNS ||= {
+    invites: %i{via_email}
+  }
+
   def up
-    Migration::ColumnDropper.execute_drop(:invites, %i{via_email})
+    DROPPED_COLUMNS.each do |table, columns|
+      Migration::ColumnDropper.execute_drop(table, columns)
+    end
   end
 
   def down