Trip Booking (Saga)

Book multiple services with automatic rollback on failure.

book_tripPending

Decline the card

trip_booking.ex

defmodule MyApp.TripBooking do
  use Durable
  use Durable.Helpers

  workflow "book_trip" do
    step :book_flight, [compensate: :cancel_flight], fn ctx ->
      booking = Flights.book(ctx["flight"])
      {:ok, assign(ctx, :flight, booking)}
    end

    step :book_hotel, [compensate: :cancel_hotel], fn ctx ->
      booking = Hotels.book(ctx["hotel"])
      {:ok, assign(ctx, :hotel, booking)}
    end

    step :charge, fn ctx ->
      total = ctx.flight.price + ctx.hotel.price
      Payments.charge(ctx["card"], total)
      {:ok, assign(ctx, :charged, true)}
    end

    compensate :cancel_flight, fn ctx ->
      Flights.cancel(ctx.flight.id)
      {:ok, ctx}
    end

    compensate :cancel_hotel, fn ctx ->
      Hotels.cancel(ctx.hotel.id)
      {:ok, ctx}
    end
  end
end

The code is the README example. The run is simulated in your browser, with time sped up. For the details, read the compensations guide.