interventions_controller.rb

class InterventionsController < ApplicationController
  inherit_resources
  actions :create, :update, :edit, :new
  nested_belongs_to :patient, :drug_therapy_problem

  create! do |success, failure|
    success.html do
      @intervention.activate!("Manual communication")
    end
    failure.html { render :action => 'new', :status => :unprocessable_entity }
  end

  protected
  def build_resource
    @intervention ||= end_of_association_chain.build(params[:intervention] || {})
  end
end