Event Metainformation

After reading this guide, you will know how to attach contextual data — such as the acting user and the current request — to every event your application records.

Table of contents

1. Generating the initializer
2. Defining attributes
3. Adding validations
4. Setting values per request

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In auditable systems, knowing what happened is only part of the story — you also need to know who did it and in what context. Event metainformation lets you attach that context to every event recorded during a request, enriching your audit trail with the provenance required for compliance, debugging, and forensic analysis.

Generating the initializer

Funes ships a generator that creates a pre-configured initializer with the metainformation options already commented in:

$ bin/rails generate funes:initializer

This creates config/initializers/funes.rb with the event_metainformation_attributes and event_metainformation_validations blocks ready to uncomment and fill in. The sections below walk through each option.

Defining attributes

You configure metainformation in your application’s initializer. Start by declaring the attributes you need:

# config/initializers/funes.rb
Funes.configure do |config|
  config.event_metainformation_attributes = [:user_id, :action, :git_version]
end

These become thread-safe attributes on Funes::EventMetainformation, automatically attached to every event persisted during the same request.

Adding validations

Use the event_metainformation_validations block to enforce that the required context is always present when an event is recorded:

# config/initializers/funes.rb
Funes.configure do |config|
  config.event_metainformation_attributes = [:user_id, :action, :git_version]

  config.event_metainformation_validations do
    validates :user_id, presence: true
    validates :action, presence: true, format: { with: /\A\w+#\w+\z/ }
    validates :git_version, presence: true, format: { with: /\A[a-f0-9]{7,40}\z/ }
  end
end

The block DSL supports all standard ActiveModel validators. If metainformation fails validation at the time an event is appended, Funes raises Funes::InvalidEventMetainformation.

Setting values per request

Populate metainformation at the start of each request using a before_action. A concern keeps this wiring out of ApplicationController:

# app/controllers/concerns/trackable_events.rb
module TrackableEvents
  extend ActiveSupport::Concern

  included do
    before_action :set_event_metainformation
  end

  private
      def set_event_metainformation
        Funes::EventMetainformation.user_id = current_user&.id
        Funes::EventMetainformation.action = "#{controller_name}##{action_name}"
        Funes::EventMetainformation.git_version = ENV["GIT_VERSION"]
      end
end

# app/controllers/application_controller.rb
class ApplicationController < ActionController::Base
  include TrackableEvents
end

Every event appended during that request will carry the values set in this before_action.

Note: Funes::EventMetainformation extends ActiveSupport::CurrentAttributes, which provides thread-isolated storage that is automatically reset between requests. It is safe to use with any multi-threaded server such as Puma.