A little history: in Rails 2 days, there was a method for each type of validation. Rails 3 added an API to combine these together with the `validates` method:

```ruby
# Rails 2
validates_presence_of :name
validates_uniqueness_of :name
```

Rails 3 added a new API, so you can do:

```ruby

```

The old style validations are still valid, but the new syntax is preferred:

```ruby
validates :up_or_down, :inclusion => { :in => [-1, 1] }
```