Rails: how do I validate that something is a boolean?

Since Rails 3, you can do:

validates :field, inclusion: { in: [ true, false ] }

I believe for a boolean field you will need to do something like:

validates_inclusion_of :field_name, :in => [true, false]

From an older version of the API: "This is due to the way Object#blank? handles boolean values. false.blank? # => true"

I'm not sure if this will still be fine for Rails 3 though, hope that helped!