Add an invert method for remove_foreign_key

2 files changed, 16 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index dd7dcb9cdd..a89886721a 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -777,7 +777,10 @@ module ActiveRecord
         execute schema_creation.accept(at)
       end
 
-      # Removes the given foreign key from the table.
+      # Removes the given foreign key from the table. Any options parameters provided
+      # will be used to re-add the foreign key in case of a migration reversion.
+      # It is recommended that you provide any options used when creating the foreign
+      # key so that the migration can be reverted properly.
       #
       # Removes the foreign key on +accounts.branch_id+.
       #
@@ -791,6 +794,8 @@ module ActiveRecord
       #
       #   remove_foreign_key :accounts, name: :special_fk_name
       #
+      # The +options+ hash can include all keys that can be used in add_foreign_key.
+      # Please refer to the add_foreign_key documentation for a full list
       def remove_foreign_key(from_table, options_or_to_table = {})
         return unless supports_foreign_keys?
 
diff --git a/activerecord/lib/active_record/migration/command_recorder.rb b/activerecord/lib/active_record/migration/command_recorder.rb
index 36256415df..ee4545ed71 100644
--- a/activerecord/lib/active_record/migration/command_recorder.rb
+++ b/activerecord/lib/active_record/migration/command_recorder.rb
@@ -184,6 +184,16 @@ module ActiveRecord
         [:remove_foreign_key, [from_table, options]]
       end
 
+      def invert_remove_foreign_key(args)
+        from_table, to_table, remove_options = args
+        raise ActiveRecord::IrreversibleMigration, "remove_foreign_key is only reversible if given a second table" if to_table.nil? || to_table.is_a?(Hash)
+
+        reversed_args = [from_table, to_table]
+        reversed_args << remove_options if remove_options
+
+        [:add_foreign_key, reversed_args]
+      end
+
       # Forwards any missing method call to the \target.
       def method_missing(method, *args, &block)
         if @delegate.respond_to?(method)