Use self.ignored_columns += instead of =

This is to accomodate prepended modules.

app/models/application_setting.rb

@@ -24,14 +24,14 @@ class ApplicationSetting < ApplicationRecord
   serialize :domain_blacklist, Array # rubocop:disable Cop/ActiveRecordSerialize
   serialize :repository_storages # rubocop:disable Cop/ActiveRecordSerialize
-  self.ignored_columns = %i[
-                         clientside_sentry_dsn
-                         clientside_sentry_enabled
-                         koding_enabled
-                         koding_url
-                         sentry_dsn
-                         sentry_enabled
-                         ]
+  self.ignored_columns += %i[
+    clientside_sentry_dsn
+    clientside_sentry_enabled
+    koding_enabled
+    koding_url
+    sentry_dsn
+    sentry_enabled
+  ]
   cache_markdown_field :sign_in_text
   cache_markdown_field :help_page_text

app/models/ci/build.rb

@@ -17,14 +17,14 @@ module Ci
     BuildArchivedError = Class.new(StandardError)
-    self.ignored_columns = %i[
-                           artifacts_file
-                           artifacts_file_store
-                           artifacts_metadata
-                           artifacts_metadata_store
-                           artifacts_size
-                           commands
-                           ]
+    self.ignored_columns += %i[
+      artifacts_file
+      artifacts_file_store
+      artifacts_metadata
+      artifacts_metadata_store
+      artifacts_size
+      commands
+    ]
     belongs_to :project, inverse_of: :builds
     belongs_to :runner

app/models/deploy_key.rb

@@ -10,7 +10,7 @@ class DeployKey < Key
   scope :are_public,  -> { where(public: true) }
   scope :with_projects, -> { includes(deploy_keys_projects: { project: [:route, :namespace] }) }
-  self.ignored_columns = %i[can_push]
+  self.ignored_columns += %i[can_push]
   accepts_nested_attributes_for :deploy_keys_projects

app/models/note.rb

@@ -33,7 +33,7 @@ class Note < ApplicationRecord
     end
   end
-  self.ignored_columns = %i[original_discussion_id]
+  self.ignored_columns += %i[original_discussion_id]
   cache_markdown_field :note, pipeline: :note, issuable_state_filter_enabled: true

app/models/notification_setting.rb

 # frozen_string_literal: true
 class NotificationSetting < ApplicationRecord
-
-  self.ignored_columns = %i[events]
+  self.ignored_columns += %i[events]
   enum level: { global: 3, watch: 2, participating: 1, mention: 4, disabled: 0, custom: 5 }

app/models/user.rb

@@ -23,11 +23,11 @@ class User < ApplicationRecord
   DEFAULT_NOTIFICATION_LEVEL = :participating
-  self.ignored_columns = %i[
-                         authentication_token
-                         email_provider
-                         external_email
-                         ]
+  self.ignored_columns += %i[
+    authentication_token
+    email_provider
+    external_email
+  ]
   add_authentication_token_field :incoming_email_token, token_generator: -> { SecureRandom.hex.to_i(16).to_s(36) }
   add_authentication_token_field :feed_token

doc/development/what_requires_downtime.md

@@ -50,7 +50,7 @@ places. This can be done by defining the columns to ignore. For example, to igno
 ```ruby
 class User < ApplicationRecord
-  self.ignored_columns = %i[updated_at]
+  self.ignored_columns += %i[updated_at]
 end
 ```