proposed behavior for #filter using :attributes adapter

[nscricco]

Expected behavior vs actual behavior

Right now my application has a problem with deeply nested response bodies. Ideally, I would like to keep all the existing associations in the serializers and limit the attributes of nested associations in the controller.

(see below for full associations)

ActiveModelSerializers.config.adapter = :attributes
ActiveModelSerializers.config.default_includes = '**'

class PostsController < BaseController
  def index
    posts = Post.all.includes(:author, :comment)
    render json: posts, include: 'author', fields: { post: [:id, :title, :author], comment: [:id, :body] }
  end
end

response.body = {
  title: 
  author: {
    name:
    birthday:
  }
  comments: [
    {
      id:
      body:
    }
  ]
}

I know that in the past, the default serializer in Rails < 4.0 one could do the following:

render json: posts, include: {author: true, comment: [:id, :body]}, fields: [:id, :title]

Would it be useful for fields to be able to filter the attributes on nested associations?

Steps to reproduce

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

I wrote a few tests that can be seen here

class PostSerializer < ActiveModel::Serializer
  attributes :title, :body
  belongs_to :author
  has_many :comments
end

class AuthorSerializer < ActiveModel::Serializer
  attributes :name, :birthday
end

class CommentSerializer < ActiveModel::Serializer
  attributes :body
  belongs_to :author
end

@author = Author.new(id: 1, name: 'Nick', birthday: '06.02.1988')
@comment1 = Comment.new(id: 7, body: 'cool', author: @author)
@comment2 = Comment.new(id: 12, body: 'awesome', author: @author)
@post = Post.new(id: 1337, title: 'Title 1', body: 'Body 1',
                                  author: @author, comments: [@comment1, @comment2])
@comment1.post = @post
@comment2.post = @post

fields = { posts: [:title, :author], comments: [:body] }
serializable = ActiveModelSerializers::SerializableResource.new(@post, adapter: :attributes, fields: fields, include: 'comments,author').serializable_hash
expected = [
  title: 'Title 1',
  author: {
    name: 'Nick',
    birthday: '06.02.1988'
  },
  comments: [
    {
      id: '7',
      body: 'cool'
    }, {
      id: '12',
      body: 'awesome'
    }
  ]
]

Environment

ActiveModelSerializers Version (commit ref if not on tag): 2423ca49995a

Output of ruby -e "puts RUBY_DESCRIPTION": ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin15]

OS Type & Version: OS X 10.11.4 (15E2066)

[NullVoxPopuli]

it looks like you need to include author as well in your include parameter.

[bf4]

Would it be useful for fields to be able to filter the attributes on nested associations?

Is this basically backporting JSON API adapter behavior to the Attributes adapter?

[nscricco]

Yes, exactly. If you think it's worth adding I am happy to put up a PR for it.

[NullVoxPopuli]

This just further proves the need to unify everything.

[bf4]

Very closely related to https://github.com/rails-api/active_model_serializers/issues/1843

@nscricco Since there's a lot involved, might be best to pick something small and make a lot of small prs. Join us on the amserializers.herokuapp.com slack to discuss .