Merge branch 'master' of github.com:brynary/arel

3 files changed, 13 insertions, 3 deletions

diff --git a/lib/arel.rb b/lib/arel.rb
index 14511d5b38..ef2308ca53 100644
--- a/lib/arel.rb
+++ b/lib/arel.rb
@@ -1,6 +1,7 @@
 require 'active_support/inflector'
-require 'active_support/core_ext/module/delegation'
 require 'active_support/core_ext/class/attribute_accessors'
+require 'active_support/core_ext/module/delegation'
+require 'active_support/core_ext/object/blank'
 
 module Arel
   require 'arel/algebra'
diff --git a/lib/arel/algebra/relations/operations/where.rb b/lib/arel/algebra/relations/operations/where.rb
index 608aaeb4b7..2fc51c7f24 100644
--- a/lib/arel/algebra/relations/operations/where.rb
+++ b/lib/arel/algebra/relations/operations/where.rb
@@ -9,6 +9,15 @@ module Arel
       @predicate = predicate.bind(@relation)
     end
 
+    def engine
+      # Temporary check of whether or not the engine supports where.
+      if relation.engine.respond_to?(:supports) && !relation.engine.supports(:where)
+        Memory::Engine.new
+      else
+        relation.engine
+      end
+    end
+
     def wheres
       @wheres ||= (relation.wheres + [predicate]).collect { |p| p.bind(self) }
     end
diff --git a/lib/arel/session.rb b/lib/arel/session.rb
index d844cd7423..c7fcc53a3b 100644
--- a/lib/arel/session.rb
+++ b/lib/arel/session.rb
@@ -11,13 +11,13 @@ module Arel
           begin
             @started = true
             @instance = manufacture
-            metaclass.class_eval do
+            singleton_class.class_eval do
               undef :new
               alias_method :new, :instance
             end
             yield
           ensure
-            metaclass.class_eval do
+            singleton_class.class_eval do
               undef :new
               alias_method :new, :manufacture
             end