1 files changed, 20 insertions, 6 deletions
diff --git a/activerecord/lib/active_record/associations/association.rb b/activerecord/lib/active_record/associations/association.rb
index 930f678ae8..d64ab64c99 100644
--- a/activerecord/lib/active_record/associations/association.rb
+++ b/activerecord/lib/active_record/associations/association.rb
@@ -163,9 +163,12 @@ module ActiveRecord
         @reflection = @owner.class._reflect_on_association(reflection_name)
       end
 
-      def initialize_attributes(record) #:nodoc:
+      def initialize_attributes(record, except_from_scope_attributes = nil) #:nodoc:
+        except_from_scope_attributes ||= {}
         skip_assign = [reflection.foreign_key, reflection.type].compact
-        attributes = create_scope.except(*(record.changed - skip_assign))
+        assigned_keys = record.changed
+        assigned_keys += except_from_scope_attributes.keys.map(&:to_s)
+        attributes = create_scope.except(*(assigned_keys - skip_assign))
         record.assign_attributes(attributes)
         set_inverse_instance(record)
       end
@@ -211,9 +214,12 @@ module ActiveRecord
         # the kind of the class of the associated objects. Meant to be used as
         # a sanity check when you are about to assign an associated record.
         def raise_on_type_mismatch!(record)
-          unless record.is_a?(reflection.klass) || record.is_a?(reflection.class_name.constantize)
-            message = "#{reflection.class_name}(##{reflection.klass.object_id}) expected, got #{record.class}(##{record.class.object_id})"
-            raise ActiveRecord::AssociationTypeMismatch, message
+          unless record.is_a?(reflection.klass)
+            fresh_class = reflection.class_name.safe_constantize
+            unless fresh_class && record.is_a?(fresh_class)
+              message = "#{reflection.class_name}(##{reflection.klass.object_id}) expected, got #{record.class}(##{record.class.object_id})"
+              raise ActiveRecord::AssociationTypeMismatch, message
+            end
           end
         end
 
@@ -245,9 +251,17 @@ module ActiveRecord
 
         def build_record(attributes)
           reflection.build_association(attributes) do |record|
-            initialize_attributes(record)
+            initialize_attributes(record, attributes)
           end
         end
+
+        # Returns true if statement cache should be skipped on the association reader.
+        def skip_statement_cache?
+          reflection.scope_chain.any?(&:any?) ||
+            scope.eager_loading? ||
+            klass.scope_attributes? ||
+            reflection.source_reflection.active_record.default_scopes.any?
+        end
     end
   end
 end