Polymorphic filters

class Filter < ActiveRecord::Base
  belongs_to :context, polymorphic: true
  belongs_to :filter, polymorphic: true
end

class Foo < ActiveRecord::Base
  has_many :filters, as: :context
  
  def role_filters
    self.filters.where(filter_type: 'Role')
  end

  def shop_filters
    self.filters.where(filter_type: 'Shop')
  end

  def role_filter_ids
    role_filters.map(&:filter_id)
  end

  def shop_filter_ids
    shop_filters.map(&:filter_id)
  end
  
  def role_filters=
    // complicated stuff goes here, instead of controller!
  end
  
  def shop_filters=
    // complicated stuff goes here, instead of controller!
  end
end