NoMethodError: undefined method `singularize' for nil:NilClass

[dasnixon]

This is currently only happening in production, so I wonder if it has something to do with caching. I did try to run Rails.cache.clear and I touched a few records in the DB to see if that would fix the issue. I am running on Heroku with ruby 2.3.0 and rails 4.2.6

API Request

/api/v1/jobs?include=business&page=1&per_page=10

Culprit

https://github.com/rails-api/active_model_serializers/blob/v0.10.0.rc5/lib/active_model/serializer/fieldset.rb#L13

My Serializer

module Api
  module V1
    class JobSerializer < ActiveModel::Serializer
      cache key: 'api-v1-job'
      attributes :id, :job_role, :description, :perks, :job_type, :wage,
        :age_requirement, :posted_on, :enabled, :application_site,
        :start_timeframe, :location, :live, :highlighted, :category_list,
        :latitude, :longitude
      type :jobs

      has_one :business,
        serializer: Api::V1::BusinessSerializer,
        embed: :id,
        embed_key: :to_param

      def id
        object.to_param
      end

      def live
        object.live?
      end

      def category_list
        object.categories.pluck(:name)
      end
    end
  end
end

Overridden Collection Serializer

class NamespacedCollectionSerializer < ActiveModel::Serializer::CollectionSerializer
  def initialize(resources, options = {})
    @object                  = resources
    @options                 = options
    @root                    = options[:root]
    serializer_context_class = options.fetch(:serializer_context_class, ActiveModel::Serializer)
    namespace                = options.fetch(:namespace)
    @serializers = resources.map do |resource|
      resource_serializer = "#{resource.class.name.demodulize}Serializer"
      resource_serializer = "#{namespace}::#{resource_serializer}" if namespace.present?
      serializer_class = resource_serializer.constantize

      if serializer_class.nil? # rubocop:disable Style/GuardClause
        fail NoSerializerError, "No serializer found for resource: #{resource.inspect}"
      else
        serializer_class.new(resource, options.except(:serializer, :namespace))
      end
    end
  end
end

Stacktrace

File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model/serializer/fieldset.rb" line 13 in fields_for
2
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/adapter/json_api.rb" line 299 in resource_object_for
3
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/adapter/json_api.rb" line 241 in process_resource
4
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/adapter/json_api.rb" line 231 in block in resource_objects_for
5
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model/serializer/collection_serializer.rb" line 6 in each
6
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model/serializer/collection_serializer.rb" line 6 in each
7
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/adapter/json_api.rb" line 231 in resource_objects_for
8
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/adapter/json_api.rb" line 74 in success_document
9
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/adapter/json_api.rb" line 49 in serializable_hash
10
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/adapter/base.rb" line 27 in as_json
11
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/json/encoding.rb" line 35 in encode
12
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/json/encoding.rb" line 22 in encode
13
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/core_ext/object/json.rb" line 37 in to_json_with_active_support_encoder
14
File "/app/vendor/ruby-2.3.0/lib/ruby/2.3.0/delegate.rb" line 341 in block in delegating_block
15
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/serializable_resource.rb" line 8 in to_json 
16
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/logging.rb" line 69 in block (3 levels) in notify
17
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 117 in call
18
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 555 in block (2 levels) in compile
19
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 505 in call
20
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 498 in block (2 levels) in around
21
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 343 in block (2 levels) in simple
22
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/logging.rb" line 22 in block (3 levels) in instrument_rendering
23
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/logging.rb" line 79 in block in notify_render
24
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/notifications.rb" line 164 in block in instrument
25
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/notifications/instrumenter.rb" line 20 in instrument
26
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/notifications.rb" line 164 in instrument
27
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/logging.rb" line 78 in notify_render
28
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/logging.rb" line 21 in block (2 levels) in instrument_rendering
29
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/logging.rb" line 95 in block in tag_logger
30
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/tagged_logging.rb" line 68 in block in tagged
31
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/tagged_logging.rb" line 26 in tagged
32
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/tagged_logging.rb" line 68 in tagged
33
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/logging.rb" line 95 in tag_logger
34
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/logging.rb" line 20 in block in instrument_rendering
35
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 441 in instance_exec
36
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 441 in block in make_lambda
37
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 342 in block in simple
38
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 497 in block in around
39
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 505 in call
40
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 92 in __run_callbacks__
41
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 778 in _run_render_callbacks
42
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/callbacks.rb" line 81 in run_callbacks
43
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/active_model_serializers/logging.rb" line 68 in block (2 levels) in notify
44
File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-4.2.6/lib/action_controller/metal/renderers.rb" line 116 in block in <module:Renderers>
45
File "/app/vendor/bundle/ruby/2.3.0/gems/active_model_serializers-0.10.0.rc5/lib/action_controller/serialization.rb" line 52 in block (2 levels) in <module:Serialization>
46
File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-4.2.6/lib/action_controller/metal/renderers.rb" line 45 in block in _render_to_body_with_renderer 
47
File "/app/vendor/ruby-2.3.0/lib/ruby/2.3.0/set.rb" line 306 in each_key
48
File "/app/vendor/ruby-2.3.0/lib/ruby/2.3.0/set.rb" line 306 in each
49
File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-4.2.6/lib/action_controller/metal/renderers.rb" line 41 in _render_to_body_with_renderer
50
File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-4.2.6/lib/action_controller/metal/renderers.rb" line 37 in render_to_body
51
File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-4.2.6/lib/abstract_controller/rendering.rb" line 25 in render
52
File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-4.2.6/lib/action_controller/metal/rendering.rb" line 16 in render
53
File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-4.2.6/lib/action_controller/metal/instrumentation.rb" line 44 in block (2 levels) in render
54
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/core_ext/benchmark.rb" line 12 in block in ms
55
File "/app/vendor/ruby-2.3.0/lib/ruby/2.3.0/benchmark.rb" line 308 in realtime
56
File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.6/lib/active_support/core_ext/benchmark.rb" line 12 in ms
57
File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-4.2.6/lib/action_controller/metal/instrumentation.rb" line 44 in block in render
58
File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-4.2.6/lib/action_controller/metal/instrumentation.rb" line 87 in cleanup_view_runtime
59
File "/app/vendor/bundle/ruby/2.3.0/gems/activerecord-4.2.6/lib/active_record/railties/controller_runtime.rb" line 25 in cleanup_view_runtime
60
File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-4.2.6/lib/action_controller/metal/instrumentation.rb" line 43 in render
61
File "/app/app/controllers/concerns/api_response.rb" line 51 in render_resource
62
File "/app/app/controllers/concerns/api_response.rb" line 22 in respond_with
63
File "/app/app/controllers/api/v1/jobs_controller.rb" line 32 in index

[beauby]

What seems to be happening here is that somehow the type of the resource is not being properly determined. I suspect this line to be responsible. cc @remear

[dasnixon]

After some debugging locally and turning on caching I was able to reproduce
the issue. The cache lookup returns an object with they keys as strings.
This is trying to lookup by symbol which is causing the nil. I can submit a
PR but it uses with_indifferent_access. I know that's not efficient.

On Tuesday, April 19, 2016, Lucas Hosseini notifications@github.com wrote:

What seems to be happening here is that somehow the type of the resource
is not being properly determined. I suspect this line
https://github.com/rails-api/active_model_serializers/blob/v0.10.0.rc5/lib/active_model_serializers/adapter/json_api/resource_identifier.rb#L8
to be responsible. cc @remear https://github.com/remear

—
You are receiving this because you authored the thread.
Reply to this email directly or view it on GitHub
#1691 (comment)

-Chris Nixon

[beauby]

Oh, interesting catch! cc @bf4

[dasnixon]

[dasnixon]

Per @beauby as of writing this (caching will be fully working in a future release), caching slows down response time. Therefore, the quickest fix for this was to disable caching altogether, which I did by removing the line cache key....

module Api
  module V1
    class JobSerializer < ActiveModel::Serializer
      # (REMOVE THIS) cache key: 'api-v1-job'
      attributes :id, :job_role, :description, :perks, :job_type, :wage,
        :age_requirement, :posted_on, :enabled, :application_site,
        :start_timeframe, :location, :live, :highlighted, :category_list,
        :latitude, :longitude
      type :jobs

[ianks]

I have also been experiencing some bugs with the newest changes to caching.

I was caching like this:

3   cache
4 
5   delegate :cache_key, to: :object

And would get errors like this:

NoMethodError: undefined method `utc' for nil:NilClass

Backtrace

[GEM_ROOT]/bundler/gems/rails-2d744fee9c05/activerecord/lib/active_record/integration.rb:61 :in `cache_key`
[PROJECT_ROOT]/app/serializers/smart_tip_serializer.rb:5 :in `cache_key`
[GEM_ROOT]/bundler/gems/active_model_serializers-7485c8487ee6/lib/active_model/serializer/caching.rb:220 :in `cache_check`
[GEM_ROOT]/bundler/gems/active_model_serializers-7485c8487ee6/lib/active_model_serializers/adapter/base.rb:39 :in `cache_check`
[GEM_ROOT]/bundler/gems/active_model_serializers-7485c8487ee6/lib/active_model_serializers/adapter/json_api.rb:289 :in `resource_object_for`
[GEM_ROOT]/bundler/gems/active_model_serializers-7485c8487ee6/lib/active_model_serializers/adapter/json_api.rb:240 :in `process_resource`

[beauby]

cc @bf4

[bf4]

@ianks re:

delegate :cache_key, to: :object

So, in master this is actually now the default case. see #1642

active_model_serializers/lib/active_model/serializer/caching.rb

Lines 320 to 329 in 7485c84

	def object_cache_key
	if object.respond_to?(:cache_key)
	object.cache_key
	elsif (serializer_cache_key = (self.class._cache_key || self.class._cache_options[:key]))
	object_time_safe = object.updated_at
	object_time_safe = object_time_safe.strftime('%Y%m%d%H%M%S%9N') if object_time_safe.respond_to?(:strftime)
	"#{serializer_cache_key}/#{object.id}-#{object_time_safe}"
	else
	fail UndefinedCacheKey, "#{object.class} must define #cache_key, or the 'key:' option must be passed into '#{self.class}.cache'"
	end

I'm not sure where the utc error would be coming from.

[adaam2]

@bf4 If you're delegating cache_key to object (like @ianks is above) then it passes through to the cache key method as defined by AR:

"/usr/local/bundle/gems/activerecord-4.2.9/lib/active_record/integration.rb:61:in `cache_key'\n",
 "/app/app/serializers/base_serializer.rb:8:in `cache_key'\n",
 "/usr/local/bundle/gems/active_model_serializers-0.10.5/lib/active_model/serializer/concerns/caching.rb:207:in `fetch_attributes'\n",
 "/usr/local/bundle/gems/active_model_serializers-0.10.5/lib/active_model/serializer.rb:166:in `serializable_hash'\n"

So therefore object is nil for some reason, which tends to suggest that something is awry with AMS

[bf4]

@adaam2 Please open a new issue. I'm not sure why you're defining delegate :cache_key, to: :object, but that's not expected