Remove the MTI query if doing a calculation.

Author: voltechs

lib/active_record/mti/calculations.rb

@@ -4,6 +4,79 @@ module Calculations
 
       private
 
+      def execute_grouped_calculation(operation, column_name, distinct) #:nodoc:
+        group_attrs = group_values
+
+        if group_attrs.first.respond_to?(:to_sym)
+          association  = @klass._reflect_on_association(group_attrs.first)
+          associated   = group_attrs.size == 1 && association && association.belongs_to? # only count belongs_to associations
+          group_fields = Array(associated ? association.foreign_key : group_attrs)
+        else
+          group_fields = group_attrs
+        end
+        group_fields = arel_columns(group_fields)
+
+        group_aliases = group_fields.map { |field|
+          column_alias_for(field)
+        }
+        group_columns = group_aliases.zip(group_fields).map { |aliaz,field|
+          [aliaz, field]
+        }
+
+        group = group_fields
+
+        if operation == 'count' && column_name == :all
+          aggregate_alias = 'count_all'
+        else
+          aggregate_alias = column_alias_for([operation, column_name].join(' '))
+        end
+
+        select_values = [
+          operation_over_aggregate_column(
+            aggregate_column(column_name),
+            operation,
+            distinct).as(aggregate_alias)
+        ]
+        select_values += select_values unless having_values.empty?
+
+        select_values.concat group_fields.zip(group_aliases).map { |field,aliaz|
+          if field.respond_to?(:as)
+            field.as(aliaz)
+          else
+            "#{field} AS #{aliaz}"
+          end
+        }
+
+        relation = except(:group)
+        relation.group_values  = group
+        relation.select_values = select_values
+
+        # Remove our cast otherwise PSQL will insist that it be included in the GROUP
+        relation.arel.projections.select!{ |p| p.to_s != "cast(\"#{klass.table_name}\".\"tableoid\"::regclass as text)" } if @klass.using_multi_table_inheritance?
+
+        calculated_data = @klass.connection.select_all(relation, nil, relation.arel.bind_values + bind_values)
+
+        if association
+          key_ids     = calculated_data.collect { |row| row[group_aliases.first] }
+          key_records = association.klass.base_class.find(key_ids)
+          key_records = Hash[key_records.map { |r| [r.id, r] }]
+        end
+
+        Hash[calculated_data.map do |row|
+          key = group_columns.map { |aliaz, col_name|
+            column = calculated_data.column_types.fetch(aliaz) do
+              type_for(col_name)
+            end
+            type_cast_calculated_value(row[aliaz], column)
+          }
+          key = key.first if key.size == 1
+          key = key_records[key] if associated
+
+          column_type = calculated_data.column_types.fetch(aggregate_alias) { type_for(column_name) }
+          [key, type_cast_calculated_value(row[aggregate_alias], column_type, operation)]
+        end]
+      end
+
       def execute_simple_calculation(operation, column_name, distinct) #:nodoc:
         # Postgresql doesn't like ORDER BY when there are no GROUP BY
         relation = unscope(:order)
@@ -27,9 +100,9 @@ def execute_simple_calculation(operation, column_name, distinct) #:nodoc:
           column_alias ||= @klass.connection.column_name_for_operation(operation, select_value)
           relation.select_values = [select_value]
 
-          # Only use the last projection (probably the COUNT(*)) all others don't matter
-          # relation.arel.projections = [relation.arel.projections.last].compact if @klass.using_multi_table_inheritance?
-          relation.arel.projections.shift if @klass.using_multi_table_inheritance?
+          # Remove our cast otherwise PSQL will insist that it be included in the GROUP
+          # Somewhere between line 82 and 101 relation.arel.projections gets reset :/
+          relation.arel.projections.select!{ |p| p.to_s != "cast(\"#{klass.table_name}\".\"tableoid\"::regclass as text)" } if @klass.using_multi_table_inheritance?
 
           query_builder = relation.arel
           bind_values = query_builder.bind_values + relation.bind_values

lib/active_record/mti/version.rb

@@ -1,5 +1,5 @@
 module ActiveRecord
   module MTI
-    VERSION = "0.0.2"
+    VERSION = '0.0.5'
   end
 end