First in your terminal:
rails g migration change_field_format_in_my_table
Then in your migration file:
class ChangeFieldFormatInMyTable < ActiveRecord::Migration
def up
change_column :my_table, :my_column, :new_type
end
def down
change_column :my_table, :my_column, :old_type
end
end
rails g migration change_field_format_in_my_table
Then in your migration file:
class ChangeFieldFormatInMyTable < ActiveRecord::Migration
def up
change_column :my_table, :my_column, :new_type
end
def down
change_column :my_table, :my_column, :old_type
end
end