diff options
Diffstat (limited to 'activerecord/lib/active_record/migration/command_recorder.rb')
-rw-r--r-- | activerecord/lib/active_record/migration/command_recorder.rb | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/migration/command_recorder.rb b/activerecord/lib/active_record/migration/command_recorder.rb new file mode 100644 index 0000000000..25b8649350 --- /dev/null +++ b/activerecord/lib/active_record/migration/command_recorder.rb @@ -0,0 +1,48 @@ +module ActiveRecord + class Migration + # ActiveRecord::Migration::CommandRecorder records commands done during + # a migration and knows how to reverse those commands. + class CommandRecorder + attr_reader :commands + + def initialize + @commands = [] + end + + # record +command+. +command+ should be a method name and arguments. + # For example: + # + # recorder.record(:method_name, [:arg1, arg2]) + def record(*command) + @commands << command + end + + # Returns a list that represents commands that are the inverse of the + # commands stored in +commands+. + def inverse + @commands.map { |name, args| send(:"invert_#{name}", args) } + end + + private + def invert_create_table(args) + [:drop_table, args] + end + + def invert_rename_table(args) + [:rename_table, args.reverse] + end + + def invert_add_column(args) + [:remove_column, args.first(2)] + end + + def invert_rename_index(args) + [:rename_index, args.reverse] + end + + def invert_rename_column(args) + [:rename_column, [args.first] + args.last(2).reverse] + end + end + end +end |