class Order
  attr_accessor :tracking_id, :client_ref_no, :service, :vehicle, :round_trip,
    :pickup_target_from, :pickup_target_to

  FIELD_MAPPINGS = {
    tracking_id: "OrderTrackingID".freeze,
    client_ref_no: "ClientRefNo".freeze,
    service: "Service".freeze,
    vehicle: "Vehicle".freeze,
    round_trip: "RoundTrip".freeze,
    pickup_target_from: "PickupTargetFrom".freeze,
    pickup_target_to: "PickupTargetTo".freeze,
  }.freeze

  def initialize(response_body)
    FIELD_MAPPINGS.each do |attr, key|
      public_send("#{attr}=", response_body.fetch(key))
    end
  end
end

# Usage

order = Order.new({
  "OrderTrackingID" => 603072717,
  "ClientRefNo" => "ORDER-1",
  "Service" => "Quick Delivery",
  "Vehicle" => "Car",
  "RoundTrip" => false,
  "PickupTargetFrom" => "2017-07-27T12:13:00",
  "PickupTargetTo" => "2017-07-27T13:13:00"
})

order.tracking_id
# => 60307217

order.pickup_target_from
# => "2017-07-27T12:13:00"