Activeadmin form - Rails - ruby-on-rails

Question

How I can make this form in activeadmin?
<%= form_for(#album, :html => {:multipart => true}) do |f| %>
.....
<div class="field">
<%= f.label :apellido %><br />
<%= f.text_field :apellido %>
</div>
<div class="field">
<p>Hijos</p>
<%= f.fields_for :hijos do |builder| %><br /><br />
<%= builder.label :nombre, 'Nombre Hijo' %><br />
<%= builder.text_field :nombre %><br />
<%= builder.label :apodo, 'Apodo Hijo' %><br />
<%= builder.text_field :apodo %><br />
<%= builder.label :hijo_id, 'favorito' %>
**<%= f.radio_button :hijo_id, builder.object.id %>**
<% end %>
</div>
I need put the option of hijo_id inside the for of :hijos
Try with :
f.input :avatar_item_id, :as => :boolean, :value => app_f.object.id
But not work.
Thanks

Answer 1

This should work once you register the Album model as an ActiveAdmin resource:
form :html => {:multipart => true} do |f|
f.inputs "Principal" do
f.input :apellido
end
f.inputs "Hijos" do
f.has_many :hijos do |h|
h.input :nombre
h.input :apodo
h.input :favorito, :as => :check_box
end
end
f.buttons
end
If you want to mark a child as a favorite, you need a boolean favorito field in the hijos table, not a hijo_id field.