Support pagination link for Kaminari when no data is returned

Author: iamnader

CHANGELOG.md

@@ -46,6 +46,7 @@ Features:
 - [#1340](https://github.com/rails-api/active_model_serializers/pull/1340) Add support for resource-level meta. (@beauby)
 
 Fixes:
+- [#1700](https://github.com/rails-api/active_model_serializers/pull/1700) Support pagination link for Kaminari when no data is returned
 - [#1657](https://github.com/rails-api/active_model_serializers/pull/1657) Add missing missing require "active_support/json". (@andreaseger)
 - [#1661](https://github.com/rails-api/active_model_serializers/pull/1661) Fixes `read_attribute_for_serialization` not
   seeing methods defined in serialization superclass (#1653, #1658, #1660), introduced in #1650. (@bf4)

lib/active_model_serializers/adapter/json_api/pagination_links.rb

@@ -28,7 +28,7 @@ def as_json
         private
 
         def pages_from
-          return {} if collection.total_pages == FIRST_PAGE
+          return {} if collection.total_pages <= FIRST_PAGE
 
           {}.tap do |pages|
             pages[:self] = collection.current_page

test/adapter/json_api/pagination_links_test.rb

@@ -101,6 +101,13 @@ def expected_response_with_last_page_pagination_links
           end
         end
 
+        def expected_response_with_no_data_pagination_links
+          {}.tap do |hash|
+            hash[:data] = []
+            hash[:links] = {}
+          end
+        end
+
         def test_pagination_links_using_kaminari
           adapter = load_adapter(using_kaminari, mock_request)
 
@@ -120,6 +127,22 @@ def test_pagination_links_with_additional_params
             adapter.serializable_hash
         end
 
+        def test_pagination_links_when_zero_results_kaminari
+          @array = []
+
+          adapter = load_adapter(using_kaminari(1), mock_request)
+
+          assert_equal expected_response_with_no_data_pagination_links, adapter.serializable_hash
+        end
+
+        def test_pagination_links_when_zero_results_will_paginate
+          @array = []
+
+          adapter = load_adapter(using_will_paginate(1), mock_request)
+
+          assert_equal expected_response_with_no_data_pagination_links, adapter.serializable_hash
+        end
+
         def test_last_page_pagination_links_using_kaminari
           adapter = load_adapter(using_kaminari(3), mock_request)