make `change_column_null` reversible. Closes #13576.

Closes #13623.

1 files changed, 6 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/migration/command_recorder.rb b/activerecord/lib/active_record/migration/command_recorder.rb
index 17300f0598..9139ad953c 100644
--- a/activerecord/lib/active_record/migration/command_recorder.rb
+++ b/activerecord/lib/active_record/migration/command_recorder.rb
@@ -74,7 +74,7 @@ module ActiveRecord
         :rename_index, :rename_column, :add_index, :remove_index, :add_timestamps, :remove_timestamps,
         :change_column_default, :add_reference, :remove_reference, :transaction,
         :drop_join_table, :drop_table, :execute_block, :enable_extension,
-        :change_column, :execute, :remove_columns, # irreversible methods need to be here too
+        :change_column, :execute, :remove_columns, :change_column_null # irreversible methods need to be here too
       ].each do |method|
         class_eval <<-EOV, __FILE__, __LINE__ + 1
           def #{method}(*args, &block)          # def create_table(*args, &block)
@@ -157,6 +157,11 @@ module ActiveRecord
       alias :invert_add_belongs_to :invert_add_reference
       alias :invert_remove_belongs_to :invert_remove_reference
 
+      def invert_change_column_null(args)
+        args[2] = !args[2]
+        [:change_column_null, args]
+      end
+
       # Forwards any missing method call to the \target.
       def method_missing(method, *args, &block)
         if @delegate.respond_to?(method)