Question

I have what I think is a pretty simple migration. For some reason I get an IrreversibleMigration error when I try to db:rollback or db:migrate:redo.

The migration runs smoothly, but I’d rather keep it reversible. I can’t figure out why it’s not as written. Any ideas?

Here’s the migration:

class AddWhyHypAndWhyHypeToStatements < ActiveRecord::Migration
  def change
    change_table :statements do |t|
      t.rename :description, :why_hypocritical
      t.text   :why_hypothetical
    end
  end
end

If it matters, “description” column is a text column. I’m using Rails 3.1/Ruby 1.9.2/PostgreSQL. Thanks for any help.

Answer 1

Looks like Rails has troubles reverting change_table method. Try doing it that way instead:

class AddWhyHypAndWhyHypeToStatements < ActiveRecord::Migration
  def change
    rename_column :statements, :description, :why_hypocritical
    add_column :statements, :why_hypothetical, :text
  end
end

You can see the list of commands that can be inverted in the docs or in Rails Guides.