Use active support lazy load hooks

Extend `ActiveRecord::Base` functionality only after `ActiveRecord` has
been fully loaded.

Ref: thoughtbot/factory_bot_rails#426


Close #231

lib/chrono_model.rb

@@ -2,12 +2,14 @@
 
 require 'active_record'
 
+require 'chrono_model/chrono'
 require 'chrono_model/conversions'
 require 'chrono_model/patches'
 require 'chrono_model/adapter'
 require 'chrono_model/time_machine'
 require 'chrono_model/time_gate'
 require 'chrono_model/version'
+require 'chrono_model/railtie'
 
 module ChronoModel
   class Error < ActiveRecord::ActiveRecordError # :nodoc:
@@ -33,59 +35,24 @@ def self.history_models
   end
 end
 
-if defined?(Rails::Railtie)
-  require 'chrono_model/railtie'
-end
+ActiveSupport.on_load :active_record do
+  extend ChronoModel::Chrono
 
-ActiveRecord::Base.instance_eval do
-  # Checks whether this Active Recoed model is backed by a temporal table
-  #
-  def chrono?
-    return false unless connection.respond_to? :is_chrono?
+  # Hooks into Association#scope to pass the As-Of time automatically
+  # to methods that load associated ChronoModel records.
+  ActiveRecord::Associations::Association.prepend ChronoModel::Patches::Association
 
-    connection.is_chrono?(table_name)
-  end
-end
+  # Hooks into Relation#build_arel to use `:joins` on your ChronoModels
+  # and join data from associated records As-Of time.
+  ActiveRecord::Relation.prepend ChronoModel::Patches::Relation
 
-# Hooks into Association#scope to pass the As-Of time automatically
-# to methods that load associated ChronoModel records.
-#
-ActiveRecord::Associations::Association.instance_eval do
-  prepend ChronoModel::Patches::Association
-end
+  # Hooks in two points of the AR Preloader to preload As-Of time records of
+  # associated ChronoModels. is used by `.includes`, `.preload`, and `.eager_load`.
+  ActiveRecord::Associations::Preloader.prepend ChronoModel::Patches::Preloader
 
-# Hooks into Relation#build_arel to use :joins on your ChronoModels
-# and join data from associated records As-Of time.
-#
-ActiveRecord::Relation.instance_eval do
-  prepend ChronoModel::Patches::Relation
-end
+  ActiveRecord::Associations::Preloader::Association.prepend ChronoModel::Patches::Preloader::Association
 
-# Hooks in two points of the AR Preloader to preload As-Of time records of
-# associated ChronoModels. is used by .includes, .preload and .eager_load.
-#
-ActiveRecord::Associations::Preloader.instance_eval do
-  prepend ChronoModel::Patches::Preloader
-end
+  ActiveRecord::Associations::Preloader::ThroughAssociation.prepend ChronoModel::Patches::Preloader::ThroughAssociation
 
-ActiveRecord::Associations::Preloader::Association.instance_eval do
-  prepend ChronoModel::Patches::Preloader::Association
-end
-
-ActiveRecord::Associations::Preloader::ThroughAssociation.instance_eval do
-  prepend ChronoModel::Patches::Preloader::ThroughAssociation
-end
-
-ActiveRecord::Batches::BatchEnumerator.instance_eval do
-  prepend ChronoModel::Patches::Batches::BatchEnumerator
-end
-
-if defined?(Rails::DBConsole) && Rails.version < '7.1'
-  Rails::DBConsole.instance_eval do
-    if Rails.version < '6.1'
-      prepend ChronoModel::Patches::DBConsole::Config
-    else
-      prepend ChronoModel::Patches::DBConsole::DbConfig
-    end
-  end
+  ActiveRecord::Batches::BatchEnumerator.prepend ChronoModel::Patches::Batches::BatchEnumerator
 end

lib/chrono_model/chrono.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module ChronoModel
+  # A module to add to ActiveRecord::Base to check if they are backed by
+  # temporal tables.
+  module Chrono
+    # Checks whether this Active Record model is backed by a temporal table
+    #
+    # @return [Boolean] false if the connection does not respond to is_chrono?
+    #   the result of connection.is_chrono?(table_name) otherwise
+    def chrono?
+      return false unless connection.respond_to? :is_chrono?
+
+      connection.is_chrono?(table_name)
+    end
+  end
+end

lib/chrono_model/railtie.rb

@@ -1,54 +1,62 @@
 # frozen_string_literal: true
 
-require 'active_record/tasks/chronomodel_database_tasks'
-
-module ChronoModel
-  class Railtie < ::Rails::Railtie
-    TASKS_CLASS = ActiveRecord::Tasks::ChronomodelDatabaseTasks
+if defined?(Rails)
+  module ChronoModel
+    class Railtie < ::Rails::Railtie
+      rake_tasks do
+        load 'active_record/tasks/chronomodel_database_tasks.rb'
+
+        def task_config
+          if Rails.version < '6.1'
+            ActiveRecord::Tasks::DatabaseTasks.current_config.with_indifferent_access
+          else
+            ActiveRecord::Base.connection_db_config
+          end
+        end
 
-    def task_config
-      if Rails.version < '6.1'
-        ActiveRecord::Tasks::DatabaseTasks.current_config.with_indifferent_access
-      else
-        ActiveRecord::Base.connection_db_config
-      end
-    end
+        # Register our database tasks under our adapter name
+        if Rails.version < '5.2'
+          ActiveRecord::Tasks::DatabaseTasks.register_task(/chronomodel/, ActiveRecord::Tasks::ChronomodelDatabaseTasks)
+        else
+          ActiveRecord::Tasks::DatabaseTasks.register_task(/chronomodel/, 'ActiveRecord::Tasks::ChronomodelDatabaseTasks')
+        end
 
-    # Register our database tasks under our adapter name
-    if Rails.version < '5.2'
-      ActiveRecord::Tasks::DatabaseTasks.register_task(/chronomodel/, TASKS_CLASS)
-    else
-      ActiveRecord::Tasks::DatabaseTasks.register_task(/chronomodel/, TASKS_CLASS.to_s)
-    end
+        if Rails.application.config.active_record.schema_format != :sql
+          raise 'In order to use ChronoModel, config.active_record.schema_format must be :sql!'
+        end
 
-    rake_tasks do
-      if Rails.application.config.active_record.schema_format != :sql
-        raise 'In order to use ChronoModel, config.active_record.schema_format must be :sql!'
-      end
+        if Rails.version < '6.1'
+          # Make schema:dump and schema:load invoke structure:dump and structure:load
+          Rake::Task['db:schema:dump'].clear.enhance(['environment']) do
+            Rake::Task['db:structure:dump'].invoke
+          end
 
-      if Rails.version < '6.1'
-        # Make schema:dump and schema:load invoke structure:dump and structure:load
-        Rake::Task['db:schema:dump'].clear.enhance(['environment']) do
-          Rake::Task['db:structure:dump'].invoke
+          Rake::Task['db:schema:load'].clear.enhance(['environment']) do
+            Rake::Task['db:structure:load'].invoke
+          end
         end
 
-        Rake::Task['db:schema:load'].clear.enhance(['environment']) do
-          Rake::Task['db:structure:load'].invoke
+        desc 'Dumps database into db/data.NOW.sql or file specified via DUMP='
+        task 'db:data:dump' => :environment do
+          target = ENV['DUMP'] || Rails.root.join('db', "data.#{Time.now.to_f}.sql")
+          ActiveRecord::Tasks::ChronomodelDatabaseTasks.new(task_config).data_dump(target)
         end
-      end
-
-      desc 'Dumps database into db/data.NOW.sql or file specified via DUMP='
-      task 'db:data:dump' => :environment do
-        target = ENV['DUMP'] || Rails.root.join('db', "data.#{Time.now.to_f}.sql")
-        TASKS_CLASS.new(task_config).data_dump(target)
-      end
 
-      desc 'Loads database dump from file specified via DUMP='
-      task 'db:data:load' => :environment do
-        source = ENV['DUMP'].presence or
-          raise ArgumentError, 'Invoke as rake db:data:load DUMP=/path/to/data.sql'
-        TASKS_CLASS.new(task_config).data_load(source)
+        desc 'Loads database dump from file specified via DUMP='
+        task 'db:data:load' => :environment do
+          source = ENV['DUMP'].presence or
+            raise ArgumentError, 'Invoke as rake db:data:load DUMP=/path/to/data.sql'
+          ActiveRecord::Tasks::ChronomodelDatabaseTasks.new(task_config).data_load(source)
+        end
       end
     end
   end
 end
+
+if defined?(Rails::DBConsole) && Rails.version < '7.1'
+  if Rails.version < '6.1'
+    Rails::DBConsole.prepend ChronoModel::Patches::DBConsole::Config
+  else
+    Rails::DBConsole.prepend ChronoModel::Patches::DBConsole::DbConfig
+  end
+end