Add example for group migration

Author: jnunemaker

examples/active_record/ar_setup.rb

@@ -28,3 +28,18 @@
 ActiveRecord::Base.connection.execute <<-SQL
   CREATE UNIQUE INDEX index_gates_on_keys_and_value on flipper_gates (feature_key, key, value)
 SQL
+
+ActiveRecord::Base.connection.execute <<-SQL
+  CREATE TABLE users (
+    id integer PRIMARY KEY,
+    name string NOT NULL,
+    influencer boolean,
+    created_at datetime NOT NULL,
+    updated_at datetime NOT NULL
+  )
+SQL
+
+require 'flipper/model/active_record'
+class User < ActiveRecord::Base
+  include Flipper::Model::ActiveRecord
+end

examples/active_record/group_migration.rb

@@ -0,0 +1,68 @@
+# This is an example script that shows how to migrate from a bunch of individual
+# actors to a group. Should be useful for those who have ended up with large
+# actor sets and want to slim them down for performance reasons.
+
+require_relative "./ar_setup"
+require 'flipper/adapters/active_record'
+require 'active_support/all'
+
+# 1. enable feature for 100 actors, make 80 influencers
+users = 100.times.map do |n|
+  influencer = n < 80 ? true : false
+  user = User.create(name: n, influencer: influencer)
+  Flipper.enable :stats, user
+  user
+end
+
+# check enabled, should all be because individual actors are enabled
+print 'Should be [[true, 100]]: '
+print users.group_by { |user| Flipper.enabled?(:stats, user) }.map { |result, users| [result, users.size]}
+puts
+
+# 2. register a group so flipper knows what to do with it
+Flipper.register(:influencers) do |actor, context|
+  actor.respond_to?(:influencer) && actor.influencer
+end
+
+# 3. enable group for feature, THIS IS IMPORTANT
+Flipper.enable :stats, :influencers
+
+# check enabled again, should all still be true because individual actors are
+# enabled, but also the group gate would return true for 80 influencers. At this
+# point, it's kind of double true but flipper just cares if any gate returns true.
+print 'Should be [[true, 100]]: '
+print users.group_by { |user| Flipper.enabled?(:stats, user) }.map { |result, users| [result, users.size]}
+puts
+
+# 4. now we want to clean up the actors that are covered by the group to slim down
+# the actor set size. So we loop through actors and remove them if group returns
+# true for the provided actor and context.
+Flipper[:stats].actors_value.each do |flipper_id|
+  # Hydrate the flipper_id into an active record object. Modify this based on
+  # your flipper_id's if you use anything other than active record models and
+  # the default flipper_id provided by flipper.
+  class_name, id = flipper_id.split(';')
+  klass = class_name.constantize
+  user = klass.find(id)
+
+  # if user is in group then disable for actor because they'll still get the feature
+  context = Flipper::FeatureCheckContext.new(
+    feature_name: :stats,
+    values: Flipper[:stats].gate_values,
+    actors: [Flipper::Types::Actor.wrap(user)]
+  )
+
+  if Flipper::Gates::Group.new.open?(context)
+    Flipper.disable(:stats, user)
+  end
+end
+
+# check enabled again, should be the same result as previous checks
+print 'Should be [[true, 100]]: '
+print users.group_by { |user| Flipper.enabled?(:stats, user) }.map { |result, users| [result, users.size]}
+puts
+
+puts "Actors enabled: #{Flipper[:stats].actors_value.size}"
+puts "Groups enabled: #{Flipper[:stats].groups_value.size}"
+
+puts "All actors that could be migrated to groups were migrated. Yay!"