I read about collection_check_boxes but I don't understand how can I set the checked values.
I have the following model:
class Objective < ActiveRecord::Base
  has_many :indicators
  has_many :objective_children, class_name: "Objective", foreign_key: "parent_id"
  def objective_ids
    objective_children.collect{|o| o.id}
  end
  def objective_ids= objectives_ids
    objectives_ids.each do |id|
      objective_children << Objective.find(id)
    end
  end
end
edit view:
<%= form_for(@objective) do |f| %>
  <%= f.collection_check_boxes :objective_ids, Objective.all, :id, :name %>
  <%= f.submit %>
<% end %>
the html checkbox are ok but I don't know how to set the values to objective. I was tried define objective_ids= objectives_ids but nothing happens.
In Controller:
class ObjectivesController < ApplicationController
    def objective_params
      params.require(:objective).permit(:name, :code, :description, :objective_ids)
    end
end
EDIT
The log file says Unpermitted parameters: perspective_id, objective_ids
 
    