Specify type of singular association during serialization

When serialising a class, specify the type of any singular associations, if
necessary. Rails already correctly specifies the :type of any enumerable
association (e.g. a has_many association), but made no attempt to do so for
non-enumerables (e.g. a has_one association).
We must specify the :type of any STI association. A has_one
association to a class which uses single-table inheritance is an example of
this type of association.

Fixes #7471

1 files changed, 6 insertions, 1 deletions

diff --git a/activemodel/lib/active_model/serializers/xml.rb b/activemodel/lib/active_model/serializers/xml.rb
index fb6093cce5..4a17a63e20 100755
--- a/activemodel/lib/active_model/serializers/xml.rb
+++ b/activemodel/lib/active_model/serializers/xml.rb
@@ -149,7 +149,12 @@ module ActiveModel
             end
           else
             merged_options[:root] = association.to_s
-            records.to_xml(merged_options)
+
+            unless records.class.to_s.underscore == association.to_s
+              merged_options[:type] = records.class.name
+            end
+
+            records.to_xml merged_options
           end
         end