title: Can not organize data in input collection
body: <p>I have <code>payment_type</code> model with 3 elements saved. Also I have an <code>order</code>, where I want to store <code>payment_type_id</code>. I write in order view: <br>
      <code>&lt;%= f.input :pay_type_id, :as => :select, collection: PaymentType.names  ...%></code><br>
  But <code>payment_type_id</code> already saves as 0. As I understand, I'm trying to record <code>payment_type.name</code> instead of <code>payment_type.id</code>. What do I have to write in <code>collection:</code> to fix it? </p>