How to include nested associations?

[piotrpalek]

Hey, let's say I have a Post model which has_many :comments. And I use it like this in the post index controller: render json: post, include: ['comments']. That works fine and includes the comments, but let's say the Comment model belongs_to :user now. Writing render json: post, include: ['comments', 'user'] doesn't "sideload" the data, is there a solution to this?

[doooks]

Hi @piotrpalek , I ran into this problem just as you posted this. I've forked and committed a failing test that shows the behaviour I was trying to produce

Does this look like the same problem to you?

3170040

[dimonzozo]

Hi @piotrpalek, @doooks. I have the same issue right now.

And I think this is design decision and if adapter will render has_many relations recursively we'll get loop. Post -> Comments -> Post -> Comments...

[piotrpalek]

My problem is with AMS 0.10-rc2 and the json-api adapter (just checking if we're talking about the same issue) and I don't know how to sideload nested relationships with that setup (or if it's possible at all).
@doooks My issue is similiar but a bit different, in my example the comment wouldn't have an author (just the post), and I would try to sideload the post's author while serializing the comment (with sideloaded post relationship).

[shicholas]

👍 having the same issue

[doooks]

do any maintainers have an opinion on this? is this feature going to be accepted if we build it?

[shicholas]

Fwiw I ended up switching to the JSON API standard. I think its handling of associated records is a great alternative to nesting json. What are your reservations to the json API spec?

[doooks]

@shicholas I'd never heard of it until recently, sure its great but I would rather have json that represents the model a bit more intuitively.

[piotrpalek]

@shicholas Are you able to "sideload" a nested relationship using JSON API? What I mean is:
Blog -> belongsTo -> Author
Comment -> belongsTo -> Blog

And now what I want to do is load all comments and sideload all the corresponding blogs but also sideload all relevant blog authors, is that possible?

[shicholas]

yup, I can do as many chains as possible with JSON API as long as the associations are declared in the serializer classes

[piotrpalek]

To include the associations you got to declare them in the controller via include: ['something'] right? Can you give an example how to include the nested associations?

[shicholas]

sure here's what I did, my example: a body has one hand which has many fingers. This should serialize a collection of bodies including hands and fingers.

class BodySerializer < ActiveModel::Serializer
    attributes(:name)

    has_one :hand

    url :body
end

class HandSerializer < ActiveModel::Serializer
    attributes(:wrist)

    belongs_to :body
    has_many :fingers

    url [:body, :hand]
end

  class FingerSerializer < ActiveModel::Serializer
    attributes(:knuckle)

    belongs_to :hand

    url [:body, :hand, :fingers]
  end

  class V1::BodyController < ApplicationController
    def index
      bodies = Body.all
      render json: bodies, include: 'hand,fingers'
    end
  end

This should give serialized bodies with both hands and fingers, is this what you had in mind @piotrpalek?

[joaomdmoura]

Hey ppl, first of all thank you all for helping each other 😄
First things first, nested associations will be a feature on 0.10.x, a lot of ppl have being requesting it. 🎉

It started back at #835, there was a PR (#952) I reviewed it a while ago, but it's broken, I'll probably pick it up in some days.
Let me know if some of you want to pick it first of work on a new implementation, I would like it to be adapter agnostic (I know JSON API is a case apart), if possible, well just let me know and we can talk it trough, otherwise I'll work on it asap, but I still need to finish a new feature that we are working on. 😄

btw @piotrpalek, you should give a try to JSON-API, awesome convention, and we really support and advise it.

[piotrpalek]

@shicholas thanks for the example I will try it later :)
@joaomdmoura yeah I will give it a try thx :)

[vyrak]

Any updates on this?

[piotrpalek]

@vyrak Well this worked for me (from schicholas example): include: ['hand.fingers'] to include the nested fingers association.