Fix issue with primary paginator being used for included resources

Fixes #1312

Author: lgebhardt

lib/jsonapi/active_relation_resource.rb

@@ -395,7 +395,7 @@ def find_related_monomorphic_fragments(source_rids, relationship, options, conne
                                                        sort_criteria: sort_criteria,
                                                        filters: filters)
 
-        paginator = options[:paginator] if source_rids.count == 1
+        paginator = options[:paginator]
 
         records = apply_request_settings_to_records(records: records_for_source_to_related(options),
                                resource_klass: resource_klass,
@@ -525,7 +525,7 @@ def find_related_polymorphic_fragments(source_rids, relationship, options, conne
                                                        relationships: linkage_relationships,
                                                        filters: filters)
 
-        paginator = options[:paginator] if source_rids.count == 1
+        paginator = options[:paginator]
 
         # Note: We will sort by the source table. Without using unions we can't sort on a polymorphic relationship
         # in any manner that makes sense

lib/jsonapi/processor.rb

@@ -392,7 +392,7 @@ def find_related_resource_id_tree(resource_klass, source_id, relationship_name,
       primary_resource_id_tree = PrimaryResourceIdTree.new
       primary_resource_id_tree.add_resource_fragments(fragments, include_related)
 
-      load_included(resource_klass, primary_resource_id_tree, include_related, options.except(:filters, :sort_criteria))
+      load_included(resource_klass, primary_resource_id_tree, include_related, options)
 
       primary_resource_id_tree
     end
@@ -406,7 +406,7 @@ def find_resource_id_tree(resource_klass, find_options, include_related)
       primary_resource_id_tree = PrimaryResourceIdTree.new
       primary_resource_id_tree.add_resource_fragments(fragments, include_related)
 
-      load_included(resource_klass, primary_resource_id_tree, include_related, options.except(:filters, :sort_criteria))
+      load_included(resource_klass, primary_resource_id_tree, include_related, options)
 
       primary_resource_id_tree
     end
@@ -422,7 +422,7 @@ def find_resource_id_tree_from_resource_relationship(resource, relationship_name
       primary_resource_id_tree = PrimaryResourceIdTree.new
       primary_resource_id_tree.add_resource_fragments(fragments, include_related)
 
-      load_included(resource_klass, primary_resource_id_tree, include_related, options.except(:filters, :sort_criteria))
+      load_included(resource_klass, primary_resource_id_tree, include_related, options)
 
       primary_resource_id_tree
     end
@@ -434,7 +434,7 @@ def load_included(resource_klass, source_resource_id_tree, include_related, opti
         relationship = resource_klass._relationship(key)
         relationship_name = relationship.name.to_sym
 
-        find_related_resource_options = options.dup
+        find_related_resource_options = options.except(:filters, :sort_criteria, :paginator)
         find_related_resource_options[:sort_criteria] = relationship.resource_klass.default_sort
         find_related_resource_options[:cache] = resource_klass.caching?
 

test/controllers/controller_test.rb

@@ -4752,3 +4752,34 @@ def test_fetch_robots_with_sort_by_version
     assert_equal 'version is not a valid sort criteria for robots', json_response['errors'].first['detail']
   end
 end
+
+class Api::V6::AuthorDetailsControllerTest < ActionController::TestCase
+  def after_teardown
+    Api::V6::AuthorDetailResource.paginator :none # TODO: ???
+  end
+
+  def test_that_the_last_two_author_details_belong_to_an_author
+    Api::V6::AuthorDetailResource.paginator :offset
+
+    total_count = AuthorDetail.count
+    assert_operator total_count, :>=, 2
+
+    assert_cacheable_get :index, params: {sort: :id, include: :author, page: {limit: 10, offset: total_count - 2}}
+    assert_response :success
+    assert_equal 2, json_response['data'].size
+    assert_not_nil json_response['data'][0]['relationships']['author']['data']
+    assert_not_nil json_response['data'][1]['relationships']['author']['data']
+  end
+
+  def test_that_the_last_author_detail_includes_its_author_even_if_returned_as_the_single_entry_on_a_page_with_nonzero_offset
+    Api::V6::AuthorDetailResource.paginator :offset
+
+    total_count = AuthorDetail.count
+    assert_operator total_count, :>=, 2
+
+    assert_cacheable_get :index, params: {sort: :id, include: :author, page: {limit: 10, offset: total_count - 1}}
+    assert_response :success
+    assert_equal 1, json_response['data'].size
+    assert_not_nil json_response['data'][0]['relationships']['author']['data']
+  end
+end