Fix lazy loaded nested associations

Fixes #129

lib/fast_jsonapi/serialization_core.rb

@@ -66,6 +66,8 @@ module FastJsonapi
       end
 
       def record_hash(record, fieldset, includes_list, params = {})
+        includes_list = parse_includes_list(includes_list)
+
         if cache_store_instance
           cache_opts = record_cache_options(cache_store_options, fieldset, includes_list, params)
           record_hash = cache_store_instance.fetch(record, **cache_opts) do
@@ -153,6 +155,9 @@ module FastJsonapi
       # @param includes_list [List] to be parsed
       # @return [Hash]
       def parse_includes_list(includes_list)
+        return {} unless includes_list.present?
+        return includes_list if includes_list.is_a?(Hash)
+
         includes_list.each_with_object({}) do |include_item, include_sets|
           include_base, include_remainder = include_item.to_s.split('.', 2)
           include_sets[include_base.to_sym] ||= Set.new

spec/fixtures/actor.rb

@@ -31,6 +31,14 @@ class ActorSerializer < UserSerializer
   ) do |object|
     object.movies
   end
+
+  has_many(
+    :lazy_played_movies,
+    serializer: :movie
+  ) do |object|
+    object.movies
+  end
+
 end
 
 class CamelCaseActorSerializer

spec/fixtures/movie.rb

@@ -72,6 +72,13 @@ class MovieSerializer
       related: ->(obj) { obj.url(obj) }
     }
   )
+  has_many(
+    :lazy_actors,
+    id_method_name: :uid,
+    lazy_load_data: true
+  ) do |object|
+    object.actors
+  end
   has_one(
     :creator,
     object_method_name: :owner,

spec/integration/relationships_spec.rb

@@ -141,6 +141,35 @@ RSpec.describe JSONAPI::Serializer do
           )
         end
       end
+
+      context 'with lazy loading' do
+        let(:params) do
+          { include: ['lazy_actors.lazy_played_movies'] }
+        end
+
+        it do
+          actors_rel = movie.actors.map { |a| { 'id' => a.uid, 'type' => 'actor' } }
+
+          expect(serialized['data']).to have_relationship('lazy_actors').with_data(actors_rel)
+
+          expect(serialized['included']).to include(
+            have_type('actor')
+            .and(have_id(movie.actors[0].uid))
+            .and(
+              have_relationship('lazy_played_movies').with_data(
+                [{
+                  'id' => movie.actors[0].movies[0].id,
+                  'type' => 'movie'
+                }]
+              )
+            )
+          )
+
+          expect(serialized['included']).to include(
+            have_type('movie').and(have_id(movie.actors[0].movies[0].id))
+          )
+        end
+      end
     end
   end
 end