Extract id_for_database in the AR object

It is not connection's concern.

activerecord/lib/active_record/attribute_methods/primary_key.rb

@@ -44,6 +44,10 @@ module ActiveRecord
         attribute_in_database(@primary_key)
       end
 
+      def id_for_database # :nodoc:
+        @attributes[@primary_key].value_for_database
+      end
+
       private
         def attribute_method?(attr_name)
           attr_name == "id" || super

activerecord/lib/active_record/connection_adapters/abstract/quoting.rb

@@ -203,9 +203,7 @@ module ActiveRecord
         end
 
         def id_value_for_database(value)
-          if primary_key = value.class.primary_key
-            value.instance_variable_get(:@attributes)[primary_key].value_for_database
-          end
+          value.id_for_database
         end
 
         def _quote(value)

activerecord/lib/active_record/sanitization.rb

@@ -193,13 +193,14 @@ module ActiveRecord
 
         def quote_bound_value(value, c = connection)
           if value.respond_to?(:map) && !value.acts_like?(:string)
-            quoted = value.map { |v| c.quote(v) }
-            if quoted.empty?
+            values = value.map { |v| v.respond_to?(:id_for_database) ? v.id_for_database : v }
+            if values.empty?
               c.quote(nil)
             else
-              quoted.join(",")
+              values.map! { |v| c.quote(v) }.join(",")
             end
           else
+            value = value.id_for_database if value.respond_to?(:id_for_database)
             c.quote(value)
           end
         end