Read model -- example.

app/assets/stylesheets/editions.scss

@@ -0,0 +1,3 @@
+// Place all the styles related to the editions controller here.
+// They will automatically be included in application.css.
+// You can use Sass (SCSS) here: https://sass-lang.com/

app/controllers/editions_controller.rb

@@ -0,0 +1,11 @@
+class EditionsController < ApplicationController
+  def show
+    edition_id = params[:id]
+
+    render :show, locals: {
+      edition_id: edition_id,
+      participants: EditionParticipant.where(edition_id: edition_id),
+      edition_status: EditionStatus.find_by(edition_id: edition_id)
+    }
+  end
+end

app/helpers/editions_helper.rb

@@ -0,0 +1,2 @@
+module EditionsHelper
+end

app/models/edition_participant.rb

@@ -0,0 +1,16 @@
+class EditionParticipant < ApplicationRecord
+  def self.handle_participant_event(event)
+    edition_id     = event.data[:edition_id]
+    participant_id = event.data[:participant_id]
+
+    case event
+    when Workshops::ParticipantPersonalDataProvided
+      where(participant_id: participant_id).update_all(
+        participant_name: event.data[:name],
+        participant_email: event.data[:email]
+      )
+    when Workshops::ParticipantRegisteredForEdition
+      find_or_create_by(edition_id: edition_id, participant_id: participant_id)
+    end
+  end
+end

app/models/edition_status.rb

@@ -0,0 +1,6 @@
+class EditionStatus < ApplicationRecord
+  def self.handle_confirmed_event(e)
+    edition_id = e.data[:edition_id]
+    find_or_create_by(edition_id: edition_id).update(status: "confirmed")
+  end
+end

app/views/editions/show.html.erb

@@ -0,0 +1,13 @@
+<h1>Edition <%= edition_id %>: <%= edition_status.status %></h1>
+
+<h3><%= participants.size %></h3>
+
+<table>
+<% participants.each do |p| %>
+    <tr>
+      <td><%= p.participant_id %></td>
+      <td><%= p.participant_name %></td>
+      <td><%= p.participant_email %></td>
+    </tr>
+<% end %>
+</table>

config/initializers/rails_event_store.rb

@@ -10,16 +10,18 @@
     config.default_event_store = Rails.configuration.event_store
   end
 
-  # Subscribe event handlers below
-  # Rails.configuration.event_store.tap do |store|
-  #   store.subscribe(InvoiceReadModel.new, to: [InvoicePrinted])
-  #   store.subscribe(->(event) { SendOrderConfirmation.new.call(event) }, to: [OrderSubmitted])
-  #   store.subscribe_to_all_events(->(event) { Rails.logger.info(event.type) })
-  # end
+  Rails.configuration.event_store.tap do |store|
+    store.subscribe(
+      ->(e) { EditionParticipant.handle_participant_event(e) },
+      to: [
+            Workshops::ParticipantRegisteredForEdition,
+            Workshops::ParticipantPersonalDataProvided,
+          ])
 
-  # Register command handlers below
-  # Rails.configuration.command_bus.tap do |bus|
-  #   bus.register(PrintInvoice, Invoicing::OnPrint.new)
-  #   bus.register(SubmitOrder,  ->(cmd) { Ordering::OnSubmitOrder.new.call(cmd) })
-  # end
+    store.subscribe(
+      ->(e) { EditionStatus.handle_confirmed_event(e) },
+      to: [
+            Workshops::EditionConfirmed,
+          ])
+  end
 end

config/routes.rb

@@ -1,4 +1,6 @@
 Rails.application.routes.draw do
   mount RailsEventStore::Browser => '/res' if Rails.env.development?
   # For details on the DSL available within this file, see https://guides.rubyonrails.org/routing.html
+
+  get '/editions/:id', to: 'editions#show'
 end

db/migrate/20200219115300_create_edition_statuses.rb

@@ -0,0 +1,10 @@
+class CreateEditionStatuses < ActiveRecord::Migration[6.0]
+  def change
+    create_table :edition_statuses do |t|
+      t.string :edition_id
+      t.string :status
+
+      t.timestamps
+    end
+  end
+end

db/migrate/20200219115312_create_edition_participants.rb

@@ -0,0 +1,12 @@
+class CreateEditionParticipants < ActiveRecord::Migration[6.0]
+  def change
+    create_table :edition_participants do |t|
+      t.string :edition_id
+      t.string :participant_id
+      t.string :participant_name
+      t.string :participant_email
+
+      t.timestamps
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,23 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_02_19_002357) do
+ActiveRecord::Schema.define(version: 2020_02_19_115312) do
+
+  create_table "edition_participants", force: :cascade do |t|
+    t.string "edition_id"
+    t.string "participant_id"
+    t.string "participant_name"
+    t.string "participant_email"
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+  end
+
+  create_table "edition_statuses", force: :cascade do |t|
+    t.string "edition_id"
+    t.string "status"
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+  end
 
   create_table "event_store_events", id: :string, limit: 36, force: :cascade do |t|
     t.string "event_type", null: false

produce.rb

@@ -0,0 +1,27 @@
+event_store = Rails.configuration.event_store
+edition_id  = "smart-pension"
+stream_name = "Edition$#{edition_id}"
+
+EditionParticipant.delete_all
+EditionStatus.delete_all
+
+event_store.publish(
+  Workshops::EditionConfirmed.new(data: { edition_id: edition_id }),
+  stream_name: stream_name
+)
+event_store.publish(
+  Workshops::ParticipantRegisteredForEdition.new(data: { edition_id: edition_id, participant_id: pid1 = SecureRandom.uuid }),
+  stream_name: stream_name
+)
+event_store.publish(
+  Workshops::ParticipantRegisteredForEdition.new(data: { edition_id: edition_id, participant_id: pid2 = SecureRandom.uuid }),
+  stream_name: stream_name
+)
+event_store.publish(
+  Workshops::ParticipantPersonalDataProvided.new(data: { participant_id: pid1, name: 'Tom', email: 't@acme' }),
+  stream_name: stream_name
+)
+event_store.publish(
+  Workshops::ParticipantPersonalDataProvided.new(data: { participant_id: pid2, name: 'Jerry', email: 'j@acme' }),
+  stream_name: stream_name
+)

test/controllers/editions_controller_test.rb

@@ -0,0 +1,7 @@
+require 'test_helper'
+
+class EditionsControllerTest < ActionDispatch::IntegrationTest
+  # test "the truth" do
+  #   assert true
+  # end
+end

test/fixtures/edition_participants.yml

@@ -0,0 +1,11 @@
+# Read about fixtures at https://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
+
+# This model initially had no columns defined. If you add columns to the
+# model remove the '{}' from the fixture names and add the columns immediately
+# below each fixture, per the syntax in the comments below
+#
+one: {}
+# column: value
+#
+two: {}
+# column: value

test/fixtures/edition_statuses.yml

@@ -0,0 +1,11 @@
+# Read about fixtures at https://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
+
+# This model initially had no columns defined. If you add columns to the
+# model remove the '{}' from the fixture names and add the columns immediately
+# below each fixture, per the syntax in the comments below
+#
+one: {}
+# column: value
+#
+two: {}
+# column: value

test/models/edition_participant_test.rb

@@ -0,0 +1,7 @@
+require 'test_helper'
+
+class EditionParticipantTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end

test/models/edition_status_test.rb

@@ -0,0 +1,7 @@
+require 'test_helper'
+
+class EditionStatusTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end

workshops/lib/workshops.rb

@@ -2,6 +2,8 @@ module Workshops
   ParticipantRegisteredForEdition = Class.new(RailsEventStore::Event)
   VenueBookedForEdition           = Class.new(RailsEventStore::Event)
   TwoWeeksBeforeEditionReached    = Class.new(RailsEventStore::Event)
+  ParticipantPersonalDataProvided = Class.new(RailsEventStore::Event)
+  EditionConfirmed                = Class.new(RailsEventStore::Event)
 
   ConfirmEdition = Struct.new(:edition_id)
   CancelEdition  = Struct.new(:edition_id)