Active Admin make a collection of attributes for a Model

I have this model attributes :

class CreateRoles < ActiveRecord::Migration
  # create role model with relation to users and projects
  def change
    create_table :roles do |t|
      t.references :user
      t.references :project
      t.boolean    :senior_author    , :default => 0
      t.boolean    :first_author     , :default => 0
      t.boolean    :author           , :default => 0
      t.boolean    :bio_informatician, :default => 0
    end
  end
end

My form is :

form do |f|
  f.inputs "Details" do # Project's fields
    f.input :title
    f.input :code
  end

  f.has_many :roles do |app_f|
    app_f.inputs do
      if !app_f.object.nil?
        app_f.input :_destroy, :as => :boolean, :label => "Effacer"
      end

      app_f.input :user, :include_blank => false, :label_method => :to_label 
      #app_f.input :senior_author
      #app_f.input :first_author
      #app_f.input :author
      #app_f.input :bio_informatician
    end
  end
  f.buttons
end

How can I make a collection () or a radio button of the four last app_f.input ?

You can use collection attribute

f.input :user, collection: User.all.map{|u| [u.name, u.id]}

I don't know if this will help you, but I think is very stranger the formtastic don't make a selection with records.