Module: Funes

Defined in:
lib/funes.rb,
lib/funes/unknown_event.rb,
lib/funes/unknown_materialization_model.rb,
app/event_streams/funes/event_stream.rb,
app/projections/funes/projection.rb,
app/models/funes/event.rb,
app/helpers/funes/projection_test_helper.rb

Overview

Funes is an event sourcing framework for Ruby on Rails.

Instead of updating state in place, Funes stores immutable events as the source of truth, then derives current state by replaying them through projections. This provides complete audit trails, temporal queries, and the ability to create multiple read models from the same event stream.

Core Concepts

  • Events (Event): Immutable facts representing something that happened
  • Event Streams (EventStream): Append-only sequences of events for a specific entity
  • Projections (Projection): Transform events into read models (state)

Getting Started

  1. Install the gem and run migrations:

    $ bin/rails generate funes:install
$ bin/rails db:migrate

  2. Define your events:

    class Order::Placed < Funes::Event
 attribute :total, :decimal
 attribute :customer_id, :string
 validates :total, presence: true
end

  3. Define a projection:

    class OrderProjection < Funes::Projection
 materialization_model OrderSnapshot

 interpretation_for Order::Placed do |state, event, as_of|
   state.assign_attributes(total: event.total)
   state
 end
end

  4. Create an event stream:

    class OrderEventStream < Funes::EventStream
 add_transactional_projection OrderProjection
end

  5. Append events:

    stream = OrderEventStream.for("order-123")
event = stream.append!(Order::Placed.new(total: 99.99, customer_id: "cust-1"))

Three-Tier Consistency Model

Funes provides fine-grained control over projection execution:

  • Consistency Projection: Validates business rules before persisting events
  • Transactional Projections: Execute synchronously in the same database transaction
  • Async Projections: Execute asynchronously via ActiveJob

See Also:

Defined Under Namespace

Modules: ProjectionTestHelper Classes: Event, EventStream, Projection, UnknownEvent, UnknownMaterializationModel