JSON adapter does not handle nested associations

[frahugo]

It only supports the associations in the model being serialized. For instance if you serialize Blog, it will serialize the posts, but not the comments of each post.

This line https://github.com/rails-api/active_model_serializers/blob/master/lib/active_model/serializer/adapter/json.rb#L14 should probably be changed to get a serializable_hash instead of just attributes.

This was discovered while trying existing 0.9.x code on the master branch. Is this something that should be supported? If so, I can submit a pull request for it.

[joaomdmoura]

I actually thought about it yesterday!
I even tried to make some tests with it locally, but it didn't seem to be the right direction.

1. Defining serializable_hash as the default behaviour would result in bigger payload.
   • It's a not a good convention.
   • Taking into account Mobile First (it isn't just about screen size, network is part of it too)
2. It would make the AMS a little bit slower.
   • It could make some cache integrations easier for me but would be a lazy choice 😝

It could be implemented as an option but Imho it isn't the way to go.
Would be cool to hear some other thoughts about it @joshsmith 😄

[a5sk4s]

+1

dealing with the very same issue at the moment with an inherited app - i agree that our request is humongous, but it's cached on the mobile client as i've been told

i was expecting that I could define a nested includes and pass the object to the serializer and it would use it, but as far as i can tell now, it stops at level one, even though the active record object has everything loaded already

[joshsmith]

I think in general this is not a good convention because of the bigger payload, as you said.

Maybe as an option, but I don't think allowing for all this configuration is a good idea, especially when it runs counter to a convention.

[frahugo]

John, when you say that it runs counter to a convention, why do you mean by that? If people want to follow a convention, they could possibly go with JSONAPI instead. The issue here is more of a backward compatibility issue.

We could use the same option as JSONAPI:

render @posts, include: ['authors', 'comments']

[joshsmith]

@frahugo is right in this case.

To reduce the number of HTTP requests, servers MAY allow responses that include related resources along with the requested primary resources. Such responses are called "compound documents".

In a compound document, all included resources MUST be represented as an array of resource objects in a top-level "included" member.

[joshsmith]

@joaomdmoura is this something that's already handled by the ActiveModel::Serializer::Adapter::JsonApi?

[joshsmith]

Here's a link to reference my above quote http://jsonapi.org/format/#document-structure-compound-documents

[joshsmith]

@frahugo I think this should be handled by the JsonApi adapter, and not the Json adapter.

[joshsmith]

This adapter, according to the documentation, does the following:

render @posts, include: ['authors', 'comments']

Am I misunderstanding the issue you're having? Do you want this to also be handled by the Json adapter itself?

[joaomdmoura]

@frahugo What @joshsmith and I meant was that it is not usual and not a convention to choose big payloads including ever object related to the resource you are retrieving.

Indeed the JsonApi adapter already enables you to retrieve included resources, but it's just one level deep.

There is a work-around to this that would be define a method at your serializer.
Imo if decide to move forward on this it should be some kind of option as you said.
Would be great to hear more toughts, @kurko I choose you! Thunder Shock! 😝

[frahugo]

A work-around would be awesome. We have existing apps that expect a JSON structure as in 0.9.x. So as long as we can provide the same JSON and that caching works, that would be awesome.

Le 2015-03-16 à 21:00, João Moura notifications@github.com a écrit :

@frahugo What @joshsmith and I meant was that it is not usual and not a convention to choose big payloads including ever object related to the resource you are retrieving.

Indeed the JsonApi adapter already enables you to retrieve included resources, but it's just one level deep.

There is a work-around to this that would be define a method at your serializer.
Imo if decide to move forward on this it should be some kind of option as you said.
Would be great to hear more toughts, @kurko I choose you! Thunder Shock!

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[joaomdmoura]

@frahugo the work around would be something like bellow:

Instead of use has_many :comments, you can add it as an attribute and define a method that will overlap it's value, inside this method you can mount any kind of object you want. In the example bellow I'm returning also the user that is related with the comments. do this solve your problem?

class PostSerializer < ActiveModel::Serializer
  attributes :title, :body, :comments

  def comments
    comments = []
    object.comments.each do |comment|
      comments << { content: comment.content, user: comment.user }
    end
  end

end

[frahugo]

Would it support caching? Caching is the main reason why we want to go with the latest code.