Rails migration for change column

Question

We have script/generate migration add_fieldname_to_tablename fieldname:datatype syntax for adding new columns to a model.

On the same line, do we have a

Answer 1

With Rails 5

From Rails Guides:

If you wish for a migration to do something that Active Record doesn’t know how to reverse, you can use reversible:

class ChangeTablenameFieldname < ActiveRecord::Migration[5.1]
  def change
    reversible do |dir|
      change_table :tablename do |t|
        dir.up   { t.change :fieldname, :date }
        dir.down { t.change :fieldname, :datetime }
      end
    end
  end
end