rails_event_store 触ってみる

stream_name = "order_1"
event =
  OrderPlaced.new(data: { order_id: 1, order_data: "sample", festival_id: "b2d506fd-409d-4ec7-b02f-c6d2295c7edd" })

#publishing an event for a specific stream
event_store.publish(event, stream_name: stream_name)

class InvoiceReadModel
  def call(event)
    # Process an event here.
  end
end

subscriber = InvoiceReadModel.new
event_store.subscribe(subscriber, to: [InvoiceCreated, InvoiceUpdated])

scope = client.read
  .stream('GoldCustomers')
  .backward
  .limit(100)
  .of_type([Customer::GoldStatusGranted])

stream_name = "Customer$1"

client.publish(MoneyDeposited.new(data: { amount: 10 }), stream_name: stream_name)
client.publish(custom_event = MoneyDeposited.new(data: { amount: 20 }), stream_name: stream_name)
client.publish(MoneyWithdrawn.new(data: { amount: 5 }), stream_name: stream_name)

account_balance =
  RailsEventStore::Projection
    .from_stream(stream_name)
    .init(-> { { total: 0 } })
    .when(MoneyDeposited, ->(state, event) { state[:total] += event.data[:amount] })
    .when(MoneyWithdrawn, ->(state, event) { state[:total] -= event.data[:amount] })

account_balance.run(client) # => {total: 25}