Serializer trying to look for attribute where it does not exist [0.10.0]

[Veske]

So I have this media serializer:

class MediumSerializer < ActiveModel::Serializer
    attributes :id,
               :text,
               :image_video_file_name,
               :image_video_croppable_url,
               :image_video_thumb_url,
               :image_video_big_url

    belongs_to :user
    has_many :comments
end

And the has_many :comments looks for this serializer:

class CommentSerializer < ActiveModel::Serializer
    attributes :id,
               :text,
               :user_id,
               :medium_id

    belongs_to :user
end

Now in my controller I am querying for media, so I get an array of mediums.

media = current_user.feed
respond_with media, each_serializer: MediumSerializer

def feed
    user_ids = $redis.smembers(self.redis_relationship_key(:following)) << id
    Medium.includes([{comments: :user}, :user]).where(user_id: user_ids)
end

And now when I load the page that uses this serializer, I get this error:

NoMethodError - undefined method `image_video_file_name' for #<Comment:0x007fa396787828>:
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  active_model_serializers (0.10.0.rc1) lib/active_model/serializer/array_serializer.rb:5:in `each'
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  active_model_serializers (0.10.0.rc1) lib/active_model/serializer/adapter/json.rb:9:in `serializable_hash'
  active_model_serializers (0.10.0.rc1) lib/active_model/serializer/adapter.rb:23:in `as_json'
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  /home/kaspar/.rbenv/versions/2.2.0/lib/ruby/2.2.0/set.rb:283:in `each_key'
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  app/controllers/users_controller.rb:73:in `feed'
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  passenger (5.0.7) lib/phusion_passenger/request_handler.rb:414:in `block (3 levels) in start_threads'
  passenger (5.0.7) lib/phusion_passenger/utils.rb:111:in `block in create_thread_and_abort_on_exception'

The error only occurs when I have an array of mediums. When I just query a single medium and use the same serializer, then the error is not there.

The image_video_file_name and the rest of similar attributes all exist in the database and are useable inside of ruby code. Also when I query a single medium, I can see all of these attributes.

What exactly is wrong here? It used to work with 0.9.x but I am using 0.10.0 now and for some reason it just does not want to work now.

[Veske]

Any idea on how to work around this nicely? I added the methods that it was throwing error about into my Comment model. Now it will pass without errors. But my Comment should not contain thoes attributes at all what it is trying to put into it.

[groyoh]

This is indeed bug due to these two lines here and here. In the first line, the ArraySerializer option contains :serializer => MediumSerializer and is passed to your MediumSerializer. This has basically no effect at this point. But then at the second line, the options hash will contains :serializer => MediumSerializer and is passed to the association serializer which is an ArraySerializer. So the serializer will serialize your comments using MediumSerializer instead of CommentSerializer.

Workaround -> Specify your association serializer, e.g.:

class MediumSerializer < ActiveModel::Serializer
  has_many :comments, serializer: CommentSerializer
end

Fix -> change this line to:

serializer_class.new(object, options.except(:serializer))

[Veske]

Thank you for the response! I hope this will get fixed soon. Will go with the workaround for now.