lib/active_median/model.rb in active_median-0.2.3 vs lib/active_median/model.rb in active_median-0.2.4

@@ -1,8 +1,18 @@
 module ActiveMedian
   module Model
     def median(column)
+      percentile(column, 0.5)
+    end
+
+    def percentile(column, percentile)
+      percentile = percentile.to_f
+      raise ArgumentError, "percentile is not between 0 and 1" if percentile < 0 || percentile > 1
+
+      # prevent SQL injection
+      percentile = connection.quote(percentile)
+
       group_values = all.group_values
 
       relation =
         case connection.adapter_name
         when /mysql/i
@@ -13,24 +23,34 @@
           if mariadb
             if group_values.any?
               over = "PARTITION BY #{group_values.join(", ")}"
             end
 
-            select(*group_values, "PERCENTILE_CONT(0.50) WITHIN GROUP (ORDER BY #{column}) OVER (#{over})").unscope(:group)
+            select(*group_values, "PERCENTILE_CONT(#{percentile}) WITHIN GROUP (ORDER BY #{column}) OVER (#{over})").unscope(:group)
           else
             # if mysql gets native function, check (and memoize) version first
-            select(*group_values, "PERCENTILE_CONT(#{column}, 0.50)")
+            select(*group_values, "PERCENTILE_CONT(#{column}, #{percentile})")
           end
         when /sqlserver/i
           if group_values.any?
             over = "PARTITION BY #{group_values.join(", ")}"
           end
 
-          select(*group_values, "PERCENTILE_CONT(0.50) WITHIN GROUP (ORDER BY #{column}) OVER (#{over})").unscope(:group)
+          select(*group_values, "PERCENTILE_CONT(#{percentile}) WITHIN GROUP (ORDER BY #{column}) OVER (#{over})").unscope(:group)
         when /sqlite/i
-          select(*group_values, "MEDIAN(#{column})")
+          case percentile.to_f
+          when 0
+            select(*group_values, "MIN(#{column})")
+          when 0.5
+            select(*group_values, "MEDIAN(#{column})")
+          when 1
+            select(*group_values, "MAX(#{column})")
+          else
+            # LOWER_QUARTILE and UPPER_QUARTILE use different calculation than 0.25 and 0.75
+            raise "SQLite only supports 0, 0.5, and 1 percentiles"
+          end
         when /postg/i, /redshift/i # postgis too
-          select(*group_values, "PERCENTILE_CONT(0.50) WITHIN GROUP (ORDER BY #{column})")
+          select(*group_values, "PERCENTILE_CONT(#{percentile}) WITHIN GROUP (ORDER BY #{column})")
         else
           raise "Connection adapter not supported: #{connection.adapter_name}"
         end
 
       result = connection.select_all(relation.to_sql)