Complete example of how to map association from Sequel::Model to AR. Eager loading works like a charm!

gistfile1.rb

class Tour < Sequel::Model
  many_to_one :vendor_pansion,
    :dataset => proc{ Vendor::Pansion.where(:id => self.vendor_pansion_id) },
    :reciprocal => nil, :class => 'Vendor::Pansion',
    :eager_loader => (proc do |opts|
      opts[:rows].each{ |object| object.associations[:vendor_pansion] = nil }

      Vendor::Pansion.where(:id => opts[:id_map].keys).each do |vendor_pansion|
        if tours = opts[:id_map][vendor_pansion.id]
          tours.each do |tour|
            tour.associations[:vendor_pansion] = vendor_pansion
          end
        end
      end
    end)
end