Return true if attribute is not changed for update_attribute

- If the attribute is not changed, then update_attribute does not run
  SQL query, this effectively means that no change was made to the
  attribute.
- This change was made in https://github.com/rails/rails/commit/0fcd4cf5
  to avoid a SQL call.
- But the change resulted into `nil` being returned when there was no
  change in the attribute value.
- This commit corrects the behavior to return true if there is no change
  in attribute value. This is same as previous behavior of Rails 4.2
  plus benefit of no additional SQL call.
- Fixes #26593.

1 files changed, 2 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/persistence.rb b/activerecord/lib/active_record/persistence.rb
index 978fb27cab..65248f3a32 100644
--- a/activerecord/lib/active_record/persistence.rb
+++ b/activerecord/lib/active_record/persistence.rb
@@ -252,7 +252,8 @@ module ActiveRecord
       name = name.to_s
       verify_readonly_attribute(name)
       public_send("#{name}=", value)
-      save(validate: false) if changed?
+
+      changed? ? save(validate: false) : true
     end
 
     # Updates the attributes of the model from the passed-in hash and saves the