Postgres event store implementation for EventSourcery
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gizotti Merge pull request #56 from envato/on-event-saved-hook-config
Introduce on_events_recoded hook to config and EventStore
Latest commit 842d90e Aug 6, 2018

README.md

EventSourcery::Postgres

Build Status

Development Status

EventSourcery is currently being used in production by multiple apps but we haven't finalized the API yet and things are still moving rapidly. Until we release a 1.0 things may change without first being deprecated.

Installation

Add this line to your application's Gemfile:

gem 'event_sourcery-postgres'

Configure

EventSourcery::Postgres.configure do |config|
  config.event_store_database = Sequel.connect(...)
  config.projections_database = Sequel.connect(...)
  config.write_events_function_name = 'writeEvents'
  config.events_table_name = :events
  config.aggregates_table_name = :aggregates
  config.callback_interval_if_no_new_events = 60
end

Usage

Event Store

ItemAdded = EventSourcery::Event

EventSourcery::Postgres.event_store.sink(ItemAdded.new(aggregate_id: uuid, body: { }}))
EventSourcery::Postgres.event_store.get_next_from(0).each do |event|
  puts event.inspect
end

Projectors & Reactors

class ItemProjector
  include EventSourcery::Postgres::Projector

  table :items do
    column :item_uuid, 'UUID NOT NULL'
    column :title, 'VARCHAR(255) NOT NULL'
  end

  project ItemAdded do |event|
    table(:items).insert(item_uuid: event.aggregate_id,
                         title: event.body.fetch('title'))
  end
end

class UserEmailer
  include EventSourcery::Postgres::Reactor

  emits_events SignUpEmailSent

  process UserSignedUp do |event|
    emit_event SignUpEmailSent.new(user_id: event.aggregate_id) do
      UserMailer.signed_up(...).deliver
    end
  end
end

EventSourcery::EventProcessing::ESPRunner.new(
  event_processors: [item_projector, user_emailer],
  event_store:      EventSourcery::Postgres.config.event_store,
  stop_on_failure:  true,
).start!

Development

After checking out the repo, run bin/setup to install dependencies. (This will install dependencies and recreate the test database.) Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install.

To release a new version:

  1. Update the version number in lib/event_sourcery/postgres/version.rb
  2. Get this change onto master via the normal PR process
  3. Run bundle exec rake release, this will create a git tag for the version, push tags up to GitHub, and upload the gem to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/envato/event_sourcery-postgres.