Allow expressions on literal SQL fragments

2 files changed, 15 insertions, 1 deletions

diff --git a/lib/arel/engines/sql/primitives.rb b/lib/arel/engines/sql/primitives.rb
index bb3bed78e6..a08ca11c12 100644
--- a/lib/arel/engines/sql/primitives.rb
+++ b/lib/arel/engines/sql/primitives.rb
@@ -3,10 +3,12 @@ module Arel
     def relation
       nil
     end
-    
+
     def to_sql(formatter = nil)
       self
     end
+
+    include Attribute::Expressions
   end
 
   class Attribute
diff --git a/spec/arel/engines/sql/unit/primitives/literal_spec.rb b/spec/arel/engines/sql/unit/primitives/literal_spec.rb
index c7ff1cf879..ed8bea339b 100644
--- a/spec/arel/engines/sql/unit/primitives/literal_spec.rb
+++ b/spec/arel/engines/sql/unit/primitives/literal_spec.rb
@@ -18,6 +18,18 @@ module Arel
           sql.should be_like(%Q{SELECT COUNT(*) AS count_id FROM "users"})
         end
       end
+
+      it "manufactures expressions on literal SQL fragment" do
+        sql = @relation.project(SqlLiteral.new("2 * credit_limit").sum).to_sql
+
+        adapter_is :mysql do
+          sql.should be_like(%Q{SELECT SUM(2 * credit_limit) AS sum_id FROM `users`})
+        end
+
+        adapter_is_not :mysql do
+          sql.should be_like(%Q{SELECT SUM(2 * credit_limit) AS sum_id FROM "users"})
+        end
+      end
     end
   end
 end