Multiple HABTM properties with ActiveAdmin and Rails 4: data not saved

Question

I have the following models:

class Programme < ActiveRecord::Base

  has_and_belongs_to_many :nationalities, class_name: 'Nation', join_table: 'nationalities_nations'
  has_and_belongs_to_many :destinations, class_name: 'Nation', join_table: 'destinations_nations'

  accepts_nested_attributes_for :nationalities
  accepts_nested_attributes_for :destinations

end

and

class Nation < ActiveRecord::Base

  has_and_belongs_to_many :nationality_programmes, class_name: 'Programme', join_table: 'nationalities_nations'
  has_and_belongs_to_many :destination_programmes, class_name: 'Programme', join_table: 'destinations_nations'

  accepts_nested_attributes_for :nationality_programmes
  accepts_nested_attributes_for :destination_programmes

end

In active admin I have the following configuration which pre-selects any existing stored country references correctly (See screenshot).

ActiveAdmin.register Programme do

  permit_params :title,
            destinations_ids: [:id],
            nationalities_ids: [:id]


  form do |f|
    f.actions
    f.inputs 'Countries / Regions' do
      f.input :nationalities, :as => :select, :input_html => {:multiple => true}
      f.input :destinations, :as => :select, :input_html => {:multiple => true}
      f.input :title
    end
    f.actions
  end
end

However, when I select other countries, the form successfully saves, but the references aren’t stored.

This is my schema:

ActiveRecord::Schema.define(version: 20140522131219) do

  create_table "destinations_nations", force: true do |t|
    t.integer "programme_id", null: false
    t.integer "nation_id",    null: false
  end

  create_table "levels_programmes", force: true do |t|
    t.integer "programme_id", null: false
    t.integer "level_id",     null: false
  end

  create_table "nationalities_nations", force: true do |t|
    t.integer "programme_id", null: false
    t.integer "nation_id",    null: false
  end

  create_table "nations", force: true do |t|
    t.string   "slug",       limit: 2
    t.string   "name"
  end

  create_table "programmes", force: true do |t|
    t.string   "title"
  end

end

Update: Cross-posted this issue on active_admin#3196 which is now closed, thanks to Gregorio's help.

Answer 1

I made it work by changing

permit_params :title,
        destinations_ids: [:id],
        nationalities_ids: [:id]

to

permit_params :title,
        destination_ids: [],
        nationality_ids: []