Use the id specified by the serializer instead of requiring id_method_name to be specified. #229

require 'jsonapi/serializer'
require 'json'

class Inner
  attr_accessor :key

  def initialize(key)
    @key = key
  end
end

class InnerSerializer
  include ::JSONAPI::Serializer

  set_type :inner
  set_id :key
end

class Outer
  attr_accessor :key, :inners

  def initialize(key, inners)
    @key = key
    @inners = inners
  end
end

class OuterSerializer
  include ::JSONAPI::Serializer

  set_type :outer
  set_id :key

  # Ideally this would "just work"
  # has_many :inners

  # Unfortunately we have to add a block because inner_ids doesn't exist
  # This seems like another possible streamline option 
  # try inner if inner_ids doesn't exist - though it might be a performance thing?
  # has_many :inners, &:inners

  # Then we need to add id_method_name - even though it is specified in the serializer
  # Is this a performance thing as well?  Is looking up the serializer slow?
  # This works, but duplicating setting `:key` is not very DRY
  has_many :inners, id_method_name: :key, &:inners
end

outer = Outer.new('outer', [Inner.new('inner1'), Inner.new('inner2')])

puts JSON.pretty_unparse(OuterSerializer.new(outer, { include: [:inners] }).serializable_hash)