Allow for alias omission in aggregate expressions

1 files changed, 15 insertions, 8 deletions

diff --git a/lib/arel/expressions.rb b/lib/arel/expressions.rb
index fa18f15b67..717cf412ee 100644
--- a/lib/arel/expressions.rb
+++ b/lib/arel/expressions.rb
@@ -4,24 +4,31 @@ module Arel
       Nodes::Count.new [self], distinct
     end
 
-    def sum
-      Nodes::Sum.new [self], Nodes::SqlLiteral.new('sum_id')
+    def sum(alias_as = "sum_id")
+      Nodes::Sum.new [self], node_alias(alias_as)
     end
 
-    def maximum
-      Nodes::Max.new [self], Nodes::SqlLiteral.new('max_id')
+    def maximum(alias_as = "max_id")
+      Nodes::Max.new [self], node_alias(alias_as)
     end
 
-    def minimum
-      Nodes::Min.new [self], Nodes::SqlLiteral.new('min_id')
+    def minimum(alias_as = "min_id")
+      Nodes::Min.new [self], node_alias(alias_as)
     end
 
-    def average
-      Nodes::Avg.new [self], Nodes::SqlLiteral.new('avg_id')
+    def average(alias_as = "avg_id")
+      Nodes::Avg.new [self], node_alias(alias_as)
     end
 
     def extract field
       Nodes::Extract.new [self], field
     end
+
+  private
+
+    def node_alias(alias_as)
+      alias_as.nil? ? nil : Nodes::SqlLiteral.new(alias_as)
+    end
+
   end
 end