Encapsulate knowledge of type objects on `ActiveRecord::Result`

Attempting to reduce the number of places that care about the details of
how type casting occurs. We remove the type casting of the primary key
in `JoinDependecy`, rather than encapsulating it. It was originally
added for consistency with
https://github.com/rails/rails/commit/40898c8c19fa04442fc5f8fb5daf3a8bdb9a1e03#diff-06059df8d3dee3101718fb2c01151ad0R211,
but that conditional was later removed in
https://github.com/rails/rails/commit/d7ddaa530fd1b94e22d745cbaf2e8a5a34ee9734.

What is important is that the same row twice will have the same value
for the primary key, which it will.

1 files changed, 1 insertions, 10 deletions

diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index c80ffbae92..b4ae204813 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -178,16 +178,7 @@ module ActiveRecord
           columns_hash.key?(cn) ? arel_table[cn] : cn
         }
         result = klass.connection.select_all(relation.arel, nil, bind_values)
-        columns = result.columns.map do |key|
-          klass.column_types.fetch(key) {
-            result.column_types.fetch(key) { result.identity_type }
-          }
-        end
-
-        result = result.rows.map do |values|
-          columns.zip(values).map { |column, value| column.type_cast_from_database value }
-        end
-        columns.one? ? result.map!(&:first) : result
+        result.cast_values(klass.column_types)
       end
     end