Fix association preloading in rails 3.2

lib/db_charmer.rb

@@ -183,8 +183,19 @@ def on_master(&block)
 ActiveRecord::Base.extend(DbCharmer::ActiveRecord::DbMagic)
 
 # Setup association preload magic
-require 'db_charmer/active_record/association_preload'
-ActiveRecord::Base.extend(DbCharmer::ActiveRecord::AssociationPreload)
+if DbCharmer.rails32?
+  require 'db_charmer/rails32/active_record/preloader/association'
+  ActiveRecord::Associations::Preloader::Association.send(:include, DbCharmer::ActiveRecord::Preloader::Association)
+  require 'db_charmer/rails32/active_record/preloader/has_and_belongs_to_many'
+  ActiveRecord::Associations::Preloader::HasAndBelongsToMany.send(:include, DbCharmer::ActiveRecord::Preloader::HasAndBelongsToMany)
+else
+  require 'db_charmer/active_record/association_preload'
+  ActiveRecord::Base.extend(DbCharmer::ActiveRecord::AssociationPreload)
+
+  # Open up really useful API method
+  ActiveRecord::AssociationPreload::ClassMethods.send(:public, :preload_associations)
+end
+
 
 class ::ActiveRecord::Base
   class << self

lib/db_charmer/rails32/active_record/preloader/association.rb

@@ -0,0 +1,21 @@
+module DbCharmer
+  module ActiveRecord
+    module Preloader
+      module Association
+        extend ActiveSupport::Concern
+        included do
+          alias_method_chain :build_scope, :db_magic
+        end
+
+        def build_scope_with_db_magic
+          if model.db_charmer_top_level_connection? || reflection.options[:polymorphic] ||
+              model.db_charmer_default_connection != klass.db_charmer_default_connection
+            build_scope_without_db_magic
+          else
+            build_scope_without_db_magic.on_db(model)
+          end
+        end
+      end
+    end
+  end
+end

lib/db_charmer/rails32/active_record/preloader/has_and_belongs_to_many.rb

@@ -0,0 +1,23 @@
+module DbCharmer
+  module ActiveRecord
+    module Preloader
+      module HasAndBelongsToMany
+        extend ActiveSupport::Concern
+        included do
+          alias_method_chain :records_for, :db_magic
+        end
+
+        def records_for_with_db_magic(ids)
+          if model.db_charmer_top_level_connection? || reflection.options[:polymorphic] ||
+              model.db_charmer_default_connection != klass.db_charmer_default_connection
+            records_for_without_db_magic(ids)
+          else
+            klass.on_db(model) do
+              records_for_without_db_magic(ids)
+            end
+          end
+        end
+      end
+    end
+  end
+end