Stack overflow when using classy_enum in the render function

[rantav]

Hi, I'm seeing some weird behavior that I can't explain and it seems to be related to classy_enum.
In my model I have:

class Message < ActiveRecord::Base
  classy_enum_attr :message_type

And I have the required enums and everything and it seems to work great. (I've used classy_enum in the past, so it's not my first enum. Other times didn't render a model with enums though)

The problem is that when I want to render a @message in the controller I get a stack overflow and sometimes (but not always) a complete server crash with class_enum in the stack

Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/classy_enum-1.3.0/lib/classy_enum/class_methods.rb:58:in `const_get': uninitialized constant MessageTypeUser (NameError)
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/classy_enum-1.3.0/lib/classy_enum/class_methods.rb:58:in `build'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/classy_enum-1.3.0/lib/classy_enum/attributes.rb:39:in `block (2 levels) in classy_enum_attr'
    from /Users/ran/dev/invi-backend/app/models/message.rb:16:in `to_s'
    from /Users/ran/dev/invi-backend/lib/messaging.rb:22:in `block in send'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/eventmachine-0.12.10/lib/em/deferrable.rb:141:in `call'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/eventmachine-0.12.10/lib/em/deferrable.rb:141:in `set_deferred_status'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/eventmachine-0.12.10/lib/em/deferrable.rb:180:in `fail'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/pusher-0.8.3/lib/pusher/channel.rb:51:in `block in trigger_async'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/eventmachine-0.12.10/lib/em/deferrable.rb:141:in `call'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/eventmachine-0.12.10/lib/em/deferrable.rb:141:in `set_deferred_status'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/eventmachine-0.12.10/lib/em/deferrable.rb:180:in `fail'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/em-http-request-0.3.0/lib/em-http/client.rb:310:in `unbind'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/eventmachine-0.12.10/lib/eventmachine.rb:1417:in `event_callback'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in `run_machine'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in `run'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/thin-1.2.11/lib/thin/backends/base.rb:61:in `start'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/thin-1.2.11/lib/thin/server.rb:159:in `start'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.2.3/lib/rack/handler/thin.rb:14:in `run'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.2.3/lib/rack/server.rb:217:in `start'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.10/lib/rails/commands/server.rb:65:in `start'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.10/lib/rails/commands.rb:30:in `block in <top (required)>'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.10/lib/rails/commands.rb:27:in `tap'
    from /Users/ran/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.10/lib/rails/commands.rb:27:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'

It's hard to say what exactly is causing this.... but when I remove the classy enum definition in the model the crash doesn't happen.

Does this ring a bell? Have you any idea why is this or how to solve that?

thanks!

[beerlington]

I have not seen that issue before. Could you post your MessageType enum class so I can try and reproduce it locally?

[rantav]

Hi Pete, thanks for the quick reply. I should say that I have no evidence that this errors stems explicitly from classy_enum, it could well be related to other things in my setup (although I wouldn't know what else to guess...) the only kind of evidence I see is that when I comment out the classy_enum_attr :message_type in the model then MessagesController.render is successful (and includes the message_type field from the db in the resulting json) and when it's in place then I see the stack overflow (and sometimes even crash).

Here's the enum code. pretty simple....

class MessageType < ClassyEnum::Base
  enum_classes :user, :system
end

class MessageTypeUser < MessageType
end

class MessageTypeSystem < MessageType
end

[beerlington]

I can't think of anything off hand that would be causing since you are definitely using it the way it was intended. I'll dig into it more this evening and see if I can reproduce.

[rantav]

Thanks, I appreciate it, I hope you can find something. I'm surprised by this as well and I can't imagine what could be causing this weird behavior. The only think not weird here is that it happens all the time consistently :(

[beerlington]

Have you tried upgrading to 1.3.1? I had fixed an issue in that version related to converting objects to JSON, and I'm wondering if that will fix your problem as well.

[rantav]

1.3.1 fixes that for me thanks!
looks like it was the json recursion thing. What's interesting is that from the console I was able to call as_json and that was ok, but probably render would do something else and recurse to death...

[rantav]

Actually, there is still a small issue - or maybe just a question.
The json looks has "message_type":{"to_s":"user","index":1}
While I would expect is to have: "message_type":"user"
Is this by design

[beerlington]

I think it's the way that Rails automatically converts the object to JSON and was not something I considered. It probably makes sense for me to add an option that lets you choose whether you want the attribute represented as the value's string or as a JSON object.

Not sure how I'd implement it yet, but I think something like this would make sense:

classy_enum_attr :message_type, :serialize_as_json => false

[rantav]

if you implement that it'd be cool. would certainly make the json response
cleaner.

On Fri, Nov 11, 2011 at 6:25 PM, Pete B <
reply@reply.github.com>wrote:

I think it's the way that Rails automatically converts the object to JSON
and was not something I considered. It probably makes sense for me to add
an option that lets you choose whether you want the attribute represented
as the value's string or as a JSON object.

Not sure how I'd implement it yet, but I think something like this would
make sense:

classy_enum_attr :message_type, :serialize_as_json => false

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/Ran
http://tavory.com

[beerlington]

Just pushed an updated gem v 1.3.2 which adds the serialize_as_json option. I decided that the default should not serialize the enum object and simply returns a string. This means you will not need to make any changes to your code to get the behavior you were expecting.

[rantav]

Awesome man, thanks!

On Nov 12, 2011, at 10:51 PM, Pete B
reply@reply.github.com
wrote:

Just pushed an updated gem v 1.3.2 which adds the serialize_as_json option. I decided that the default should not serialize the enum object and simply returns a string. This means you will not need to make any changes to your code to get the behavior you were expecting.

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