Lightweight method to order on boolean attribute in true/false/nil order

Question

Is there a lightweight way of doing something like this?

Foo.order(:bar => [true, false, nil]).map{|f| f.bar}.uniq
=> [true, false, nil]
Foo.order(:bar => [true, false, nil]).class
=> Foo::ActiveRecord_Relation

The following aren't what I want:

Foo.order(:bar).map{|f| f.bar}.uniq
=> [false, true, nil]

Foo.order("bar DESC").map{|f| f.bar}.uniq
=> [nil, true, false]

Answer 1

Found the answer:

Foo.order("bar DESC NULLS LAST").map{|f| f.bar}.uniq
=> [true, false, nil]
Foo.order("bar DESC NULLS LAST").class
=> Foo::ActiveRecord_Relation