ActiveModelSerializers::Model is broken or documentation is out of date

[joelpresence]

Expected behavior vs actual behavior

Thanks for your hard work on AMS! :-)

Expected: If I follow the official AMS documentation to create my own serializable resource that inherits from ActiveModelSerializers::Model, it should work and not fail with a syntax error.

Actual: fails with error:

rails console> class SomeResource < ActiveModelSerializers::Model; attributes :title, :body; end
NoMethodError: undefined method `attributes' for SomeResource:Class
Did you mean?  attribute_method?
	from (irb):17:in `<class:SomeResource>'

Steps to reproduce

(e.g., detailed walkthrough, runnable script, example application)

Follow the instructions to create your own serializable resource (quoting instructions):

# either
class SomeResource < ActiveRecord::Base
  # columns: title, body
end
# or
class SomeResource < ActiveModelSerializers::Model
  attributes :title, :body
end

The method attributes does NOT exist on the class ActiveModelSerializers::Model as you can see:

rails console> ActiveModelSerializers::Model.methods.sort.find_all { |m| m =~ /attributes/ }
=> []

We can actually inspect the class itself at /Users/joel/.rvm/gems/ruby-2.3.3/gems/active_model_serializers-0.10.3/lib/active_model_serializers/model.rb:

# ActiveModelSerializers::Model is a convenient
# serializable class to inherit from when making
# serializable non-activerecord objects.
module ActiveModelSerializers
  class Model
    include ActiveModel::Model
    include ActiveModel::Serializers::JSON

    attr_reader :attributes, :errors

    def initialize(attributes = {})
      @attributes = attributes && attributes.symbolize_keys
      @errors = ActiveModel::Errors.new(self)
      super
    end

    # Defaults to the downcased model name.
    def id
      attributes.fetch(:id) { self.class.name.downcase }
    end

    # Defaults to the downcased model name and updated_at
    def cache_key
      attributes.fetch(:cache_key) { "#{self.class.name.downcase}/#{id}-#{updated_at.strftime('%Y%m%d%H%M%S%9N')}" }
    end

    # Defaults to the time the serializer file was modified.
    def updated_at
      attributes.fetch(:updated_at) { File.mtime(__FILE__) }
    end

    def read_attribute_for_serialization(key)
      if key == :id || key == 'id'
        attributes.fetch(key) { id }
      else
        attributes[key]
      end
    end

    # The following methods are needed to be minimally implemented for ActiveModel::Errors
    # :nocov:
    def self.human_attribute_name(attr, _options = {})
      attr
    end

    def self.lookup_ancestors
      [self]
    end
    # :nocov:
  end
end

No attributes method that I can see.

The only way I could get this to work is as follows:

class SomeResource <ActiveModelSerializers::Model
  attr_accessor :title, :body
end

That works just fine and serializes as expected.

So either the documentation is wrong (and needs to mention attr_accessor) or the code is wrong in ActiveModelSerializers::Model (and needs to add the attributes class method) or both?

Any ideas how to fix this or if I missed something obvious?

This is on a rails app generated using rails new my_app --database=postgresql --api in case that matters.

I verified that I can reproduce this repeatedly on a brand new rails app (with active_model_serializers 0.10.3 installed) so this is definitely not a problem with my rails app or my setup: it is perfectly repeatable on a clean new rails app.

Environment

ActiveModelSerializers Version (commit ref if not on tag):

0.10.3

Output of ruby -e "puts RUBY_DESCRIPTION":

ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-darwin16]

OS Type & Version:

OS X 10.12.1

Integrated application and version (e.g., Rails, Grape, etc):

rails 5.0.0.1
ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-darwin16]
OS X 10.12.1

Backtrace

(e.g., provide any applicable backtraces from your application)

Additonal helpful information

(e.g., Gemfile.lock, configurations, PR containing a failing test, git bisect results)

[bf4]

Thanks for the report. Closed by #2000

[bf4]

@joelpresence We're not quite ready to release that API. Am working on it.

[joelpresence]

@bf4 thanks for responding, but how do I see the correct documentation for 0.10.3 that shows how to use ActiveModelSerializers::Model since the README on master shows examples that cause syntax errors ... Is there a link to documentation for 0.10.3 as released?

Also, what do you mean by "that API"?

Thanks again and take care!

[joelpresence]

Oh, https://github.com/rails-api/active_model_serializers/tree/v0.10.3 , I see, thanks! I see that it mentions attr_accessor.

[mltsy]

Ooooh! Thanks 😄 Same problem. I really have to get better at identifying the correct version of documentation for the gems I'm using!