Initial commit

app/models/custom_rank_order.rb

@@ -0,0 +1,24 @@
+class CustomRankOrder
+  def initialize(attribute, ordered_values)
+    @attribute = attribute
+    @ordered_values = ordered_values
+  end
+
+  def sql
+    Arel.sql case_statement
+  end
+
+  private
+
+  attr_accessor :attribute, :ordered_values
+
+  def case_statement
+    ["CASE", case_conditions, "END"].join(" ")
+  end
+
+  def case_conditions
+    ordered_values.map.with_index do |release, index|
+      "WHEN #{attribute}='#{release}' THEN '#{index+1}'"
+    end.join(" ")
+  end
+end