[JSON-API] Recursive has_many :children (include tree)

[Felix Bünemann]

It should be possible to express recursive relationships using JSONAPI has_one/has_many.

Without has_one/has_many I could just use a self-referential collection:

class TaxonRepresenter < Roar::Decorator
  include Roar::JSON::JSONAPI

  LimitDepth = ->(user_options: {}, **) {
    user_options[:depth] ? depth < user_options[:depth] : true
  }

  type :taxons
  property :id

  property :name
  # ...

  collection :children, extend: self, class: Taxon, if: LimitDepth
end
# Serialize up to depth 2
TaxonRepresenter.prepare(taxon).to_hash(user_options: { depth: 2 })

However has_one/has_many requires a block, so I can't just specify self as the decorator.

After looking at the source of Roar::JSON::JSONAPI I came up with this beautiful solution hack:

class TaxonRepresenter < Roar::Decorator
  include Roar::JSON::JSONAPI

  LimitDepth = ->(user_options: {}, **) {
    user_options[:depth] ? depth < user_options[:depth] : true
  }

  type :taxons
  property :id

  class RelationshipRepresenter < self; end

  property :name
  # ...

  nested :included do
    collection :children, decorator: TaxonRepresenter, class: Taxon, if: LimitDepth
  end

  nested :relationships do
    collection :children, decorator: RelationshipRepresenter, class: Taxon, if: LimitDepth
  end

end

Surely there should be an easier solution, given that trees are not exactly uncommon.

I'm using roar master and representable 3.0.0.

[Felix Bünemann]

After thinking some more about it. Shouldn't it be possible to call has_one/has_many without a block and then just pass decorator, class, erc as an option?

In most casey where I habe an association I will already have a usable decorator for the collection class.

[Alexander Brandon Coles]

This issue was moved to trailblazer/roar-jsonapi#9