Method: ActiveRecord::Migration#revert

Defined in:
lib/active_record/migration.rb

#revert(*migration_classes) ⇒ Object

Reverses the migration commands for the given block and the given migrations.

The following migration will remove the table ‘horses’ and create the table ‘apples’ on the way up, and the reverse on the way down.

class FixTLMigration < ActiveRecord::Migration
  def change
    revert do
      create_table(:horses) do |t|
        t.text :content
        t.datetime :remind_at
      end
    end
    create_table(:apples) do |t|
      t.string :variety
    end
  end
end

Or equivalently, if TenderloveMigration is defined as in the documentation for Migration:

require_relative '2012121212_tenderlove_migration'

class FixupTLMigration < ActiveRecord::Migration
  def change
    revert TenderloveMigration

    create_table(:apples) do |t|
      t.string :variety
    end
  end
end

This command can be nested.



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# File 'lib/active_record/migration.rb', line 453

def revert(*migration_classes)
  run(*migration_classes.reverse, revert: true) unless migration_classes.empty?
  if block_given?
    if @connection.respond_to? :revert
      @connection.revert { yield }
    else
      recorder = CommandRecorder.new(@connection)
      @connection = recorder
      suppress_messages do
        @connection.revert { yield }
      end
      @connection = recorder.delegate
      recorder.commands.each do |cmd, args, block|
        send(cmd, *args, &block)
      end
    end
  end
end