Header extraction failing with helper class

[bvogel]

We use a helper class to extract our csv formatings from our model class. This will break from versions 3.1 onwards, 3.0.6 was the last working version.

Model:

class Article < ActiveRecord::Base
  belongs_to :brand
  belongs_to :category

  comma do
    article_no 'Article-No'
    csv_formatter brand_name: 'Marke', model_name: 'Variante'
  end
protected
  def csv_formatter
    @csv_formatter ||= ArticleCsvFormatter.new(self, self.category, self.brand)
  end
end

Helper:

class ArticleCsvFormatter
  def initialize(article, category, brand)
    @article = article
    @category = category
    @brand = brand
  end

  def brand_name
    @brand.name
  end

  def model_name
    @category.model_name if @category
  end
end

Error message:
NoMethodError: undefined method `klass' for nil:NilClass

Stacktrace:

/gems/comma-3.2.0/lib/comma/header_extractor.rb:45 in "get_association_class"
/gems/comma-3.2.0/lib/comma/header_extractor.rb:25 in "block (2 levels) in method_missing"
/gems/comma-3.2.0/lib/comma/header_extractor.rb:24 in "each"
/gems/comma-3.2.0/lib/comma/header_extractor.rb:24 in "block in method_missing"
/gems/comma-3.2.0/lib/comma/header_extractor.rb:21 in "each"
/gems/comma-3.2.0/lib/comma/header_extractor.rb:21 in "method_missing"
[/app/models/article.rb:81 in "block in <class:Article>"](https://github.com/reverseretail/buddy/tree/master/app/models/article.rb#L81)
/gems/comma-3.2.0/lib/comma/extractor.rb:15 in "instance_eval"
/gems/comma-3.2.0/lib/comma/extractor.rb:15 in "results"
/gems/comma-3.2.0/lib/comma/object.rb:24 in "extract_with"
/gems/comma-3.2.0/lib/comma/object.rb:17 in "to_comma_headers"
/gems/comma-3.2.0/lib/comma/generator.rb:30 in "append_csv"
/gems/comma-3.2.0/lib/comma/generator.rb:21 in "block in run"
[/usr/local/lib/ruby/1.9.1/csv.rb:1243 in "generate"](https://github.com/reverseretail/buddy/tree/master/usr/local/lib/ruby/1.9.1/csv.rb#L1243)
/gems/comma-3.2.0/lib/comma/generator.rb:21 in "run"
/gems/comma-3.2.0/lib/comma/relation.rb:3 in "to_comma"
[/lib/services/excel_export.rb:53 in "export_csv"](https://github.com/reverseretail/buddy/tree/master/lib/services/excel_export.rb#L53)
[/app/controllers/articles_controller.rb:42 in "block (2 levels) in index"](https://github.com/reverseretail/buddy/tree/master/app/controllers/articles_controller.rb#L42)
/gems/actionpack-3.2.15/lib/action_controller/metal/mime_responds.rb:196 in "call"
/gems/actionpack-3.2.15/lib/action_controller/metal/mime_responds.rb:196 in "respond_to"
[/app/controllers/articles_controller.rb:39 in "index"](https://github.com/reverseretail/buddy/tree/master/app/controllers/articles_controller.rb#L39)
/gems/actionpack-3.2.15/lib/action_controller/metal/implicit_render.rb:4 in "send_action"
/gems/actionpack-3.2.15/lib/abstract_controller/base.rb:167 in "process_action"
/gems/actionpack-3.2.15/lib/action_controller/metal/rendering.rb:10 in "process_action"
/gems/actionpack-3.2.15/lib/abstract_controller/callbacks.rb:18 in "block in process_action"
/gems/activesupport-3.2.15/lib/active_support/callbacks.rb:502 in "_run__258860530__process_action__818133685__callbacks"
/gems/activesupport-3.2.15/lib/active_support/callbacks.rb:405 in "__run_callback"
/gems/activesupport-3.2.15/lib/active_support/callbacks.rb:385 in "_run_process_action_callbacks"
/gems/activesupport-3.2.15/lib/active_support/callbacks.rb:81 in "run_callbacks"
/gems/actionpack-3.2.15/lib/abstract_controller/callbacks.rb:17 in "process_action"
/gems/actionpack-3.2.15/lib/action_controller/metal/rescue.rb:29 in "process_action"
/gems/actionpack-3.2.15/lib/action_controller/metal/instrumentation.rb:30 in "block in process_action"
/gems/activesupport-3.2.15/lib/active_support/notifications.rb:123 in "block in instrument"
/gems/activesupport-3.2.15/lib/active_support/notifications/instrumenter.rb:20 in "instrument"
/gems/activesupport-3.2.15/lib/active_support/notifications.rb:123 in "instrument"
/gems/actionpack-3.2.15/lib/action_controller/metal/instrumentation.rb:29 in "process_action"
/gems/actionpack-3.2.15/lib/action_controller/metal/params_wrapper.rb:207 in "process_action"
/gems/activerecord-3.2.15/lib/active_record/railties/controller_runtime.rb:18 in "process_action"
/gems/newrelic_rpm-3.6.9.171/lib/new_relic/agent/instrumentation/rails3/action_controller.rb:38 in "block in process_action"
/gems/newrelic_rpm-3.6.9.171/lib/new_relic/agent/instrumentation/controller_instrumentation.rb:339 in "perform_action_with_newrelic_trace"
/gems/newrelic_rpm-3.6.9.171/lib/new_relic/agent/instrumentation/rails3/action_controller.rb:37 in "process_action"
/gems/actionpack-3.2.15/lib/abstract_controller/base.rb:121 in "process"
/gems/actionpack-3.2.15/lib/abstract_controller/rendering.rb:45 in "process"
/gems/rack-mini-profiler-0.1.31/Ruby/lib/mini_profiler/profiling_methods.rb:79 in "block in profile_method"
/gems/actionpack-3.2.15/lib/action_controller/metal.rb:203 in "dispatch"
/gems/actionpack-3.2.15/lib/action_controller/metal/rack_delegation.rb:14 in "dispatch"
/gems/actionpack-3.2.15/lib/action_controller/metal.rb:246 in "block in action"
/gems/actionpack-3.2.15/lib/action_dispatch/routing/route_set.rb:73 in "call"
/gems/actionpack-3.2.15/lib/action_dispatch/routing/route_set.rb:73 in "dispatch"
/gems/actionpack-3.2.15/lib/action_dispatch/routing/route_set.rb:36 in "call"
/gems/journey-1.0.4/lib/journey/router.rb:68 in "block in call"
/gems/journey-1.0.4/lib/journey/router.rb:56 in "each"
/gems/journey-1.0.4/lib/journey/router.rb:56 in "call"
/gems/actionpack-3.2.15/lib/action_dispatch/routing/route_set.rb:608 in "call"
/gems/newrelic_rpm-3.6.9.171/lib/new_relic/rack/error_collector.rb:50 in "call"
/gems/newrelic_rpm-3.6.9.171/lib/new_relic/rack/agent_hooks.rb:28 in "call"
/gems/newrelic_rpm-3.6.9.171/lib/new_relic/rack/browser_monitoring.rb:23 in "call"
/gems/actionpack-3.2.15/lib/action_dispatch/middleware/best_standards_support.rb:17 in "call"
/gems/rack-1.4.5/lib/rack/etag.rb:23 in "call"
/gems/rack-1.4.5/lib/rack/conditionalget.rb:25 in "call"
/gems/actionpack-3.2.15/lib/action_dispatch/middleware/head.rb:14 in "call"
/gems/remotipart-1.2.1/lib/remotipart/middleware.rb:27 in "call"
/gems/actionpack-3.2.15/lib/action_dispatch/middleware/params_parser.rb:21 in "call"
/gems/actionpack-3.2.15/lib/action_dispatch/middleware/flash.rb:242 in "call"
/gems/rack-1.4.5/lib/rack/session/abstract/id.rb:210 in "context"
/gems/rack-1.4.5/lib/rack/session/abstract/id.rb:205 in "call"
/gems/actionpack-3.2.15/lib/action_dispatch/middleware/cookies.rb:341 in "call"
/gems/activerecord-3.2.15/lib/active_record/query_cache.rb:64 in "call"
/gems/activerecord-3.2.15/lib/active_record/connection_adapters/abstract/connection_pool.rb:479 in "call"
/gems/actionpack-3.2.15/lib/action_dispatch/middleware/callbacks.rb:28 in "block in call"
/gems/activesupport-3.2.15/lib/active_support/callbacks.rb:405 in "_run__348730247__call__821351200__callbacks"
/gems/activesupport-3.2.15/lib/active_support/callbacks.rb:405 in "__run_callback"
/gems/activesupport-3.2.15/lib/active_support/callbacks.rb:385 in "_run_call_callbacks"
/gems/activesupport-3.2.15/lib/active_support/callbacks.rb:81 in "run_callbacks"
/gems/actionpack-3.2.15/lib/action_dispatch/middleware/callbacks.rb:27 in "call"
/gems/actionpack-3.2.15/lib/action_dispatch/middleware/remote_ip.rb:31 in "call"
/gems/actionpack-3.2.15/lib/action_dispatch/middleware/debug_exceptions.rb:16 in "call"
/gems/actionpack-3.2.15/lib/action_dispatch/middleware/show_exceptions.rb:56 in "call"
/gems/railties-3.2.15/lib/rails/rack/logger.rb:32 in "call_app"
/gems/railties-3.2.15/lib/rails/rack/logger.rb:16 in "block in call"
/gems/activesupport-3.2.15/lib/active_support/tagged_logging.rb:22 in "tagged"
/gems/railties-3.2.15/lib/rails/rack/logger.rb:16 in "call"
/gems/actionpack-3.2.15/lib/action_dispatch/middleware/request_id.rb:22 in "call"
/gems/rack-1.4.5/lib/rack/methodoverride.rb:21 in "call"
/gems/rack-1.4.5/lib/rack/runtime.rb:17 in "call"
/gems/activesupport-3.2.15/lib/active_support/cache/strategy/local_cache.rb:72 in "call"
/gems/rack-1.4.5/lib/rack/lock.rb:15 in "call"
/gems/rack-ssl-1.3.3/lib/rack/ssl.rb:27 in "call"
/gems/rack-cache-1.2/lib/rack/cache/context.rb:136 in "forward"
/gems/rack-cache-1.2/lib/rack/cache/context.rb:245 in "fetch"
/gems/rack-cache-1.2/lib/rack/cache/context.rb:185 in "lookup"
/gems/rack-cache-1.2/lib/rack/cache/context.rb:66 in "call!"
/gems/rack-cache-1.2/lib/rack/cache/context.rb:51 in "call"
/gems/rack-mini-profiler-0.1.31/Ruby/lib/mini_profiler/profiler.rb:189 in "call"
/gems/railties-3.2.15/lib/rails/engine.rb:484 in "call"
/gems/railties-3.2.15/lib/rails/application.rb:231 in "call"
/gems/railties-3.2.15/lib/rails/railtie/configurable.rb:30 in "method_missing"
[/usr/local/lib/ruby/gems/1.9.1/gems/passenger-4.0.5/lib/phusion_passenger/rack/thread_handler_extension.rb:77 in "process_request"](https://github.com/reverseretail/buddy/tree/master/usr/local/lib/ruby/gems/1.9.1/gems/passenger-4.0.5/lib/phusion_passenger/rack/thread_handler_extension.rb#L77)
[/usr/local/lib/ruby/gems/1.9.1/gems/passenger-4.0.5/lib/phusion_passenger/request_handler/thread_handler.rb:140 in "accept_and_process_next_request"](https://github.com/reverseretail/buddy/tree/master/usr/local/lib/ruby/gems/1.9.1/gems/passenger-4.0.5/lib/phusion_passenger/request_handler/thread_handler.rb#L140)
[/usr/local/lib/ruby/gems/1.9.1/gems/passenger-4.0.5/lib/phusion_passenger/request_handler/thread_handler.rb:108 in "main_loop"](https://github.com/reverseretail/buddy/tree/master/usr/local/lib/ruby/gems/1.9.1/gems/passenger-4.0.5/lib/phusion_passenger/request_handler/thread_handler.rb#L108)
[/usr/local/lib/ruby/gems/1.9.1/gems/passenger-4.0.5/lib/phusion_passenger/request_handler.rb:441 in "block (3 levels) in start_threads"](https://github.com/reverseretail/buddy/tree/master/usr/local/lib/ruby/gems/1.9.1/gems/passenger-4.0.5/lib/phusion_passenger/request_handler.rb#L441)

Model and Helper class have been reduced to avoid complexity, line numbers in the stack trace may not coincide, but the error occurs when csv_formatter will be called for the first time.

[bvogel]

Hi Guys - this fix hasn't fixed the issue for me even with 3.2.0 I get the same error message. Only with 4a14a78 has this issue been fixed (hat tip to @epdejager) - but this commit ins't included in any release yet. Currently I forked and uped the version but I'd prefer If the current codebase would get a release.

[eitoball]

@bvogel Thanks for your heads-up.

We are preparing for version 3.2.1 and will release it soon.

@crafterm @tommeier Could you release 3.2.1? If you can add me (eitoball@gmail.com) to comma gem authors on ruby gems.org, I can release it.