1 files changed, 14 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations/association_proxy.rb b/activerecord/lib/active_record/associations/association_proxy.rb
index 241b9bfee0..e36b04ea95 100644
--- a/activerecord/lib/active_record/associations/association_proxy.rb
+++ b/activerecord/lib/active_record/associations/association_proxy.rb
@@ -53,6 +53,7 @@ module ActiveRecord
 
       def initialize(owner, reflection)
         @owner, @reflection = owner, reflection
+        reflection.check_validity!
         Array(reflection.options[:extend]).each { |ext| proxy_extend(ext) }
         reset
       end
@@ -274,6 +275,19 @@ module ActiveRecord
         def owner_quoted_id
           @owner.quoted_id
         end
+
+        def set_inverse_instance(record, instance)
+          return if record.nil? || !we_can_set_the_inverse_on_this?(record)
+          inverse_relationship = @reflection.inverse_of
+          unless inverse_relationship.nil?
+            record.send(:"set_#{inverse_relationship.name}_target", instance)
+          end
+        end
+
+        # Override in subclasses
+        def we_can_set_the_inverse_on_this?(record)
+          false
+        end
     end
   end
 end