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| -rw-r--r-- | activerecord/CHANGELOG | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG index 7f54c0fa30..f1e16ea2c1 100644 --- a/activerecord/CHANGELOG +++ b/activerecord/CHANGELOG @@ -1,5 +1,23 @@ *Rails 3.1.0 (unreleased)* +* Migrations can be defined as reversible, meaning that the migration system +will figure out how to reverse your migration. To use reversible migrations, +just define the "change" method. For example: + + class MyMigration < ActiveRecord::Migration + def change + create_table(:horses) do + t.column :content, :text + t.column :remind_at, :datetime + end + end + end + +Some things cannot be automatically reversed for you. If you know how to +reverse those things, you should define 'up' and 'down' in your migration. If +you define something in `change` that cannot be reversed, an +IrreversibleMigration exception will be raised when going down. + * Migrations should use instance methods rather than class methods: class FooMigration < ActiveRecord::Migration def up |