Always prefer class types to query types when casting `group`

When `group` is used in combination with any calculation method, the
resulting hash uses the grouping expression as the key. Currently we're
incorrectly always favoring the type reported by the query, instead of
the type known by the class. This causes differing behavior depending on
whether the adaptor actually gives proper types with the query or not.
After this change, the behavior will be the same on all adaptors -- we
see if we know the type from the class, fall back to the type from the
query, and finally fall back to the identity type.

Fixes #25595

1 files changed, 6 insertions, 4 deletions

diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index d6d92b8607..a97b71815a 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -312,8 +312,10 @@ module ActiveRecord
 
       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)
+          column = type_for(col_name) do
+            calculated_data.column_types.fetch(aliaz) do
+              Type::Value.new
+            end
           end
           type_cast_calculated_value(row[aliaz], column)
         }
@@ -346,9 +348,9 @@ module ActiveRecord
       @klass.connection.table_alias_for(table_name)
     end
 
-    def type_for(field)
+    def type_for(field, &block)
       field_name = field.respond_to?(:name) ? field.name.to_s : field.to_s.split('.').last
-      @klass.type_for_attribute(field_name)
+      @klass.type_for_attribute(field_name, &block)
     end
 
     def type_cast_calculated_value(value, type, operation = nil)