Method for finding the correct application model.

This method first checks to see if an application configuration is
defined, then gets the correct ApplicationModel. Reverts to
ActiveRecord::Base if it can't find anything.

Author: wangjohn

activerecord/lib/active_record/application_configuration.rb

@@ -3,15 +3,29 @@ module ApplicationConfiguration
     extend ActiveSupport::Concern
 
     module ClassMethods
-      def configs_from(application)
+      def configs_from(mod)
         app_model = self
 
-        application.singleton_class.instance_eval do
+        mod.singleton_class.instance_eval do
           define_method(:application_model) { app_model }
         end
 
         define_singleton_method(:configs_from_application) { application }
       end
+
+      def application_model(klass = nil)
+        return ActiveRecord::Base unless klass
+
+        klass = klass.class unless klass.respond_to?(:parents)
+
+        if klass.respond_to?(:application_model)
+          klass.application_model
+        elsif app_model = klass.parents.detect { |p| p.respond_to?(:application_model) }
+          app_model
+        else
+          ActiveRecord::Base
+        end
+      end
     end
   end
 end

activerecord/lib/active_record/fixtures.rb

@@ -837,7 +837,7 @@ def after_teardown
       self.use_transactional_fixtures = true
       self.use_instantiated_fixtures = false
       self.pre_loaded_fixtures = false
-      self.config = ActiveRecord::Base
+      self.config = ActiveRecord::Base.application_model
 
       self.fixture_class_names = Hash.new do |h, fixture_set_name|
         h[fixture_set_name] = ActiveRecord::FixtureSet.default_fixture_model_name(fixture_set_name, self.config)
@@ -916,7 +916,7 @@ def run_in_transaction?
         !self.class.uses_transaction?(method_name)
     end
 
-    def setup_fixtures(config = ActiveRecord::Base)
+    def setup_fixtures
       if pre_loaded_fixtures && !use_transactional_fixtures
         raise RuntimeError, 'pre_loaded_fixtures requires use_transactional_fixtures'
       end
@@ -925,6 +925,7 @@ def setup_fixtures(config = ActiveRecord::Base)
       @fixture_connections = []
       @@already_loaded_fixtures ||= {}
 
+      config = ActiveRecord::Base.application_model
       # Load fixtures once and begin transaction.
       if run_in_transaction?
         if @@already_loaded_fixtures[self.class]

activerecord/lib/active_record/schema_migration.rb

@@ -3,7 +3,7 @@
 require 'active_record/base'
 
 module ActiveRecord
-  class SchemaMigration < ActiveRecord::Base
+  class SchemaMigration < ApplicationModel
     class << self
       def primary_key
         nil

railties/lib/rails/generators/rails/app/templates/app/models/application_model.rb.tt

@@ -1,4 +1,3 @@
 class ApplicationModel < ActiveRecord::Base
   self.abstract_class = true
-  configs_from Rails.application
 end

railties/test/application/rake_test.rb

@@ -99,7 +99,7 @@ def test_should_not_eager_load_model_for_rake
     end
 
     def test_code_statistics_sanity
-      assert_match "Code LOC: 9     Test LOC: 0     Code to Test Ratio: 1:0.0",
+      assert_match "Code LOC: 8     Test LOC: 0     Code to Test Ratio: 1:0.0",
         Dir.chdir(app_path){ `rake stats` }
     end