From d65e3b481e72e8c76818a94353e9ac315c7c0272 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 3 Feb 2011 11:50:43 -0800
Subject: [PATCH] ARel only requires the connection from the AR class. Simply
 return the AR class rather than jump through hoops and store ivars

---
 activerecord/lib/active_record/base.rb        | 10 +---
 .../abstract/connection_specification.rb      | 48 +++++++++----------
 activerecord/test/cases/multiple_db_test.rb   |  6 +--
 3 files changed, 29 insertions(+), 35 deletions(-)

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 8750e226b9af2..4e743ec826fb9 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -747,7 +747,7 @@ def reset_column_information
         undefine_attribute_methods
         reset_column_cache
         @column_names = @content_columns = @dynamic_methods_hash = @inheritance_column = nil
-        @arel_engine = @relation = nil
+        @relation = nil
       end
 
       def reset_column_cache # :nodoc:
@@ -856,13 +856,7 @@ def arel_table
       end
 
       def arel_engine
-        @arel_engine ||= begin
-          if self == ActiveRecord::Base
-            ActiveRecord::Base
-          else
-            connection_handler.connection_pools[name] ? self : superclass.arel_engine
-          end
-        end
+        self
       end
 
       # Returns a scope for this class without taking into account the default_scope.
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
index 3716937689216..5a6d13e64b18a 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
@@ -50,34 +50,34 @@ def connection
     # may be returned on an error.
     def self.establish_connection(spec = nil)
       case spec
-        when nil
-          raise AdapterNotSpecified unless defined?(Rails.env)
-          establish_connection(Rails.env)
-        when ConnectionSpecification
-          self.connection_handler.establish_connection(name, spec)
-        when Symbol, String
-          if configuration = configurations[spec.to_s]
-            establish_connection(configuration)
-          else
-            raise AdapterNotSpecified, "#{spec} database is not configured"
-          end
+      when nil
+        raise AdapterNotSpecified unless defined?(Rails.env)
+        establish_connection(Rails.env)
+      when ConnectionSpecification
+        self.connection_handler.establish_connection(name, spec)
+      when Symbol, String
+        if configuration = configurations[spec.to_s]
+          establish_connection(configuration)
         else
-          spec = spec.symbolize_keys
-          unless spec.key?(:adapter) then raise AdapterNotSpecified, "database configuration does not specify adapter" end
+          raise AdapterNotSpecified, "#{spec} database is not configured"
+        end
+      else
+        spec = spec.symbolize_keys
+        unless spec.key?(:adapter) then raise AdapterNotSpecified, "database configuration does not specify adapter" end
 
-          begin
-            require "active_record/connection_adapters/#{spec[:adapter]}_adapter"
-          rescue LoadError => e
-            raise "Please install the #{spec[:adapter]} adapter: `gem install activerecord-#{spec[:adapter]}-adapter` (#{e})"
-          end
+        begin
+          require "active_record/connection_adapters/#{spec[:adapter]}_adapter"
+        rescue LoadError => e
+          raise "Please install the #{spec[:adapter]} adapter: `gem install activerecord-#{spec[:adapter]}-adapter` (#{e})"
+        end
 
-          adapter_method = "#{spec[:adapter]}_connection"
-          unless respond_to?(adapter_method)
-            raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter"
-          end
+        adapter_method = "#{spec[:adapter]}_connection"
+        unless respond_to?(adapter_method)
+          raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter"
+        end
 
-          remove_connection
-          establish_connection(ConnectionSpecification.new(spec, adapter_method))
+        remove_connection
+        establish_connection(ConnectionSpecification.new(spec, adapter_method))
       end
     end
 
diff --git a/activerecord/test/cases/multiple_db_test.rb b/activerecord/test/cases/multiple_db_test.rb
index bd51388e0525c..3daf81c828ea7 100644
--- a/activerecord/test/cases/multiple_db_test.rb
+++ b/activerecord/test/cases/multiple_db_test.rb
@@ -84,8 +84,8 @@ def test_transactions_across_databases
     assert_equal "Ruby Developer", Entrant.find(1).name
   end
 
-  def test_arel_table_engines
-    assert_not_equal Entrant.arel_engine, Course.arel_engine
-    assert_equal Entrant.arel_engine, Bird.arel_engine
+  def test_connections
+    assert_not_equal Entrant.connection, Course.connection
+    assert_equal Entrant.connection, Bird.connection
   end
 end