Ability example.

ability.rb

class Ability
  include CanCan::Ability

  def initialize(user)
    user ||= User.new # guest user (not logged in)
    if user.type == 'Admin'
      can :manage, [ThematicGroup, Coordinator]
      can [:read, :edit, :update], MiniCourse
      can :read, Participant
      can :panel, Admin
    elsif user.type == 'Coordinator'
      can :read, ThematicGroup do |thematic_group|
        user.thematic_group_ids.include? thematic_group.id
      end
      can [:read, :update], [Paper, Poster] do |submission|
        user.thematic_group_ids.include? submission.thematic_group_id
      end
      can :panel, Coordinator
    elsif user.type == 'Participant'
      can :manage, [Paper, Poster, MiniCourse], :participant_id => user.id
      can :panel, Participant
    end
  end
end