ActiveAdmin.register Teacher do
  permit_params :name, :contact_id

form do |f|
    f.semantic_errors *f.object.errors.keys

    f.inputs "Details" do
      f.input :name
      f.input :contact_id, :as => :select, :collection => Contact.all.collect {|contact| [contact.email] }
    end
    f.actions
  end

end