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, 2 deletions

diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb
index 7996c32bbc..114686c5d3 100644
--- a/activerecord/lib/active_record/model_schema.rb
+++ b/activerecord/lib/active_record/model_schema.rb
@@ -282,8 +282,12 @@ module ActiveRecord
       #
       # +attr_name+ The name of the attribute to retrieve the type for. Must be
       # a string
-      def type_for_attribute(attr_name)
-        attribute_types[attr_name]
+      def type_for_attribute(attr_name, &block)
+        if block
+          attribute_types.fetch(attr_name, &block)
+        else
+          attribute_types[attr_name]
+        end
       end
 
       # Returns a hash where the keys are column names and the values are