Rails 4.2.0 ActiveType::Object#save fails with ActiveModel::MissingAttributeError can't write unknown attribute ``

[mattbrictson]

Update: this affects Rails 4.2.0 only. Rails 4.2.1 does not seem to be affected.

Scenario:

• Class MyForm inherits from ActiveType::Object
• @myform has validation errors
• Controller calls @myform.save

Expectation:

• @myform.save should return false, since the object is invalid

Bug:

Instead, I get this exception:

ActiveModel::MissingAttributeError can't write unknown attribute ``

Cause:

1. When save is called and validation fails, ActiveRecord calls restore_transaction_record_state
2. This in turn calls write_attribute(self.class.primary_key, restore_state[:id])
3. But for an ActiveType::Object, primary_key is nil
4. write_attribute doesn't expect a nil attribute name, so it blows up

Workaround:

I've worked around the bug by explicitly declaring a MyForm.primary_key. I'm not sure if this has other consequences, but it seems to work:

def self.primary_key
  :id
end

Here's the relevant stack trace:

ActiveModel::MissingAttributeError - can't write unknown attribute ``:
  activerecord (4.2.0) lib/active_record/attribute.rb:124:in `with_value_from_database'
  activerecord (4.2.0) lib/active_record/attribute_set.rb:39:in `write_from_user'
  activerecord (4.2.0) lib/active_record/attribute_methods/write.rb:74:in `write_attribute_with_type_cast'
  activerecord (4.2.0) lib/active_record/attribute_methods/write.rb:56:in `write_attribute'
  activerecord (4.2.0) lib/active_record/attribute_methods/dirty.rb:92:in `write_attribute'
  activerecord (4.2.0) lib/active_record/transactions.rb:393:in `restore_transaction_record_state'
  activerecord (4.2.0) lib/active_record/core.rb:514:in `update_attributes_from_transaction_state'
  activerecord (4.2.0) lib/active_record/core.rb:508:in `sync_with_transaction_state'
  activerecord (4.2.0) lib/active_record/persistence.rb:86:in `new_record?'
  activerecord (4.2.0) lib/active_record/persistence.rb:99:in `persisted?'
  actionview (4.2.0) lib/action_view/helpers/form_helper.rb:456:in `apply_form_for_options!'
  actionview (4.2.0) lib/action_view/helpers/form_helper.rb:434:in `form_for'

[vevisystems]

We were experienced the same problem, the suggested workaround works. Thanks for the hint

[treznick]

+1

[triskweline]

I'm afraid I can't reproduce the issue:

2.1.2 :001 > class Foo < ActiveType::Object
2.1.2 :002?>     attribute :flag, :boolean
2.1.2 :003?>     validates_presence_of :flag
2.1.2 :004?>   end
 => [ActiveModel::Validations::PresenceValidator] 
2.1.2 :005 > 
2.1.2 :006 >   
2.1.2 :007 >   foo = Foo.new(flag: false)
 => #<Foo > 
2.1.2 :008 > foo.save
   (0.1ms)  BEGIN
   (0.1ms)  ROLLBACK
 => false 

[mattbrictson]

@henning-koch Sorry, my explanation was a bit misleading. The call to save works fine. The exception is encountered when the form is rendered again in the view after validation fails. Here's the stack trace for clarification. Notice the problem originates with form_for being called in the view.

ActiveModel::MissingAttributeError - can't write unknown attribute ``:
  activerecord (4.2.0) lib/active_record/attribute.rb:124:in `with_value_from_database'
  activerecord (4.2.0) lib/active_record/attribute_set.rb:39:in `write_from_user'
  activerecord (4.2.0) lib/active_record/attribute_methods/write.rb:74:in `write_attribute_with_type_cast'
  activerecord (4.2.0) lib/active_record/attribute_methods/write.rb:56:in `write_attribute'
  activerecord (4.2.0) lib/active_record/attribute_methods/dirty.rb:92:in `write_attribute'
  activerecord (4.2.0) lib/active_record/transactions.rb:393:in `restore_transaction_record_state'
  activerecord (4.2.0) lib/active_record/core.rb:514:in `update_attributes_from_transaction_state'
  activerecord (4.2.0) lib/active_record/core.rb:508:in `sync_with_transaction_state'
  activerecord (4.2.0) lib/active_record/persistence.rb:86:in `new_record?'
  activerecord (4.2.0) lib/active_record/persistence.rb:99:in `persisted?'
  actionview (4.2.0) lib/action_view/helpers/form_helper.rb:456:in `apply_form_for_options!'
  actionview (4.2.0) lib/action_view/helpers/form_helper.rb:434:in `form_for'

[mattbrictson]

@henning-koch Here is a minimal Rails app the demonstrates the issue:

https://github.com/mattbrictson/active-type-31

To run the demo:

1. Check out the repo
2. bin/setup
3. bin/rails server
4. Visit http://localhost:3000

[jhirbour]

+1

[mattbrictson]

This is fixed in activerecord 4.2.1. I upgraded my test case from Rails 4.2.0 to 4.2.1 and the bug is no longer present.

[v-sh]

Thanks for the hint.

[thatandyrose]

Was about to shoot myself dead, thanks for this! 🔫 💩

[kvanderd]

+1

[mattbrictson]

Everyone who +1'd this issue: does upgrading to Rails 4.2.1 solve the problem for you? I.e. does it eliminate the need for the def self.primary_key workaround?

[kvanderd]

Upgrading to Rails 4.2.1 solved this problem for me. Thank you for opening this issue and providing a solution.

[v-sh]

Yes, I just upgrade.

[mattbrictson]

@kvanderd @v-sh thanks for confirming! Glad to hear it worked for you, too.

[triskweline]

ActiveType 0.3.5 now refuses to load with ActiveRecord 4.2.0.