From 54303b62901737333e4620ff3a9847610a409f84 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Tue, 6 Oct 2015 19:44:44 +0200
Subject: [PATCH] Add support for toplevel JSON API links.

---
 lib/active_model/serializable_resource.rb     |  2 +-
 .../serializer/adapter/json_api.rb            |  5 +++
 test/adapter/json_api/links_test.rb           | 32 +++++++++++++++++++
 3 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 test/adapter/json_api/links_test.rb

diff --git a/lib/active_model/serializable_resource.rb b/lib/active_model/serializable_resource.rb
index 56453dd9..dea94eb1 100644
--- a/lib/active_model/serializable_resource.rb
+++ b/lib/active_model/serializable_resource.rb
@@ -1,7 +1,7 @@
 require 'set'
 module ActiveModel
   class SerializableResource
-    ADAPTER_OPTION_KEYS = Set.new([:include, :fields, :adapter, :meta, :meta_key])
+    ADAPTER_OPTION_KEYS = Set.new([:include, :fields, :adapter, :meta, :meta_key, :links])
 
     # Primary interface to composing a resource with a serializer and adapter.
     # @return the serializable_resource, ready for #as_json/#to_json/#serializable_hash.
diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 2792af09..716b34b0 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -65,6 +65,11 @@ module ActiveModel
 
           ApiObjects::JsonApi.add!(hash)
 
+          if instance_options[:links]
+            hash[:links] ||= {}
+            hash[:links].update(instance_options[:links])
+          end
+
           hash
         end
 
diff --git a/test/adapter/json_api/links_test.rb b/test/adapter/json_api/links_test.rb
new file mode 100644
index 00000000..d3b56ee9
--- /dev/null
+++ b/test/adapter/json_api/links_test.rb
@@ -0,0 +1,32 @@
+require 'test_helper'
+
+module ActiveModel
+  class Serializer
+    module Adapter
+      class JsonApi
+        class LinksTest < Minitest::Test
+          def setup
+            @post = Post.new(id: 1337, comments: [], author: nil)
+          end
+
+          def test_toplevel_links
+            hash = ActiveModel::SerializableResource.new(
+              @post,
+              adapter: :json_api,
+              links: {
+                self: {
+                  href: '//posts'
+                }
+              }).serializable_hash
+            expected = {
+              self: {
+                href: '//posts'
+              }
+            }
+            assert_equal(expected, hash[:links])
+          end
+        end
+      end
+    end
+  end
+end