Strange behaviour in exception display

Santiago,

I bundled edge rails and still have the problem somehow.
The first request (step2) renders the exception, all the following render a 500.
The log file for two requests is attached.

Karl.

Karl, works for me tell me how you did your app.

You need to have the lastest rails from github and run ruby DIR_WHERE_YOU_HAVE_RAILS_REPO/bin/rails myapp --dev

And then start doing the routes, models, and all again.

Let me know.

Santigo,

Run this script and tell me the result on your side.

Karl.

Ok i'm trying right now, try this one you.

Your patch doesn't apply cleanly on a fresh Rails edge generated app.
But try my app.

Steven,
It seems you don't have the database populated with at least one item. Did you run rake db:seed ?

I did this and I get:
uninitialized constant ActionView::CompiledTemplates::Boum. No 500 page, just a standard white-and-grey error page.

Ryan,
The first request is always OK. Try two requests in a row, and tell me the result of the second one.

I'm digging deeper and what I see now is that ActionDispatch::ShowExceptions::render_exception goes FAILSAFE while rendering this exception for the second time.

Multiple requests works for me, I'm interested as to how you can replicate this issue.

yeah it is an issue. See here http://pastie.org/937107. When you start server you get proper error page with exception. On second request you get "500 Internal Server Error"

Anil,

I don't get this exact trace, but that's the point.

Two interresing points :
- First, the association gets loaded even if not used (in my example), - Second, the exception fire two times as expected, but the middleware goes fail safe with can't dup nil class on the second rendering (may be something to do with template compiler ?)

All,

The cause of the problem is that _request_and_response.erb template inspects the current controller throught request.env["action_controller.instance"]

In my example app this reference the @subitems instance variable.

If I prevent this to happen by adding <%@request.env.delete("action_controller.instance")%> to _request_and_response.erb , everything goes fine.

Why all this lead to a can't dup nil class in ActiveRecord::Base.scoped_methods (Cause of the 500) ? To be continued...

I too got a 500 Internal Server Error by following the steps provided by Karl.

I created a gist of the rails server output => http://gist.github.com/401967 -- Note that I have demarcated the logs of the two requests. Before the " Started GET "/subitems/index" " of the second request a error is shown as follows:

Error during failsafe response:
ActionView::Template::Error (can't dup NilClass) in /home/rohit/.rvm/gems/ruby-1.9.2-head/gems/actionpack-3.0.0.beta3/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb:

Also by switching to Subitem.all the 500 error doesn't appear.

Forgot to mention my environment:
Ubuntu 10.04
ruby 1.9.2dev (2010-05-08 trunk 27665) [x86_64-linux]
Rails 3.0.0.beta3

verified

See pasties for info about the logs

https://gist.github.com/2cc2371975ade98b85e5
http://pastie.org/937107

Environment:
Macbook Pro Snow Leopard
ruby-1.8.7-p249 [ x86_64 ]
Rails 3 master branch "a0621c1086165e4b3cff71b54f08a190851b6314"

Attached is rails app with which this bug is reproducible.

This is happening, I believe, because in ActiveRecord::Base

    def scoped_methods #:nodoc:
      key = :"#{self}_scoped_methods"
      Thread.current[key] = Thread.current[key].presence || self.default_scoping.dup
    end

On the second request self.default_scoping is nil as opposed to []. This causes an exception trying to dup nil. However, I cannot see what is setting the default_scoping to nil

I had the same problem when using Tyler Kovac's HyperBase with is a subclass of ActiveRecord::Base.

default_scoping is defined as a class_inheritable_accessor in base.rb. It gets initialized in ActiveRecord::Base and HyperBase wasn't able to see the default value. Adding "self.default_scoping = self.superclass.default_scoping" to HyperBase resolved the situation. I'm not sure if that is a smart fix, though. It is my understanding that this is the intende behavior of class_inheritable_accessor.

What I don't understand is why most ActiveRecord::Base subclasses to see the default value for default_Scoping (which is []). Can somebody from the team explain how that works?

This problem was killing me, hope I could help a little bit.

Can't reproduce on Safari, Chrome or Firefox on OSX, Rails 3.0.0 and ruby 1.9.2p0.

Andrea, the ticket is already closed as 'resolved'. :)

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