From 84197e4dad7f03047cd2f2ec9a0d154ebd5c6ef2 Mon Sep 17 00:00:00 2001
From: Benjamin Fleischer <github@benjaminfleischer.com>
Date: Thu, 24 Mar 2016 21:56:35 -0500
Subject: [PATCH 1/2] SerializableResource handles no serializer like
 controller

---
 CHANGELOG.md                              |  1 +
 lib/action_controller/serialization.rb    | 20 ++++++--------------
 lib/active_model/serializable_resource.rb | 10 +++++++++-
 3 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 304707bb..b4231093 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 Breaking changes:
 
 Features:
+- [#1616](https://github.com/rails-api/active_model_serializers/pull/1616) SerializableResource handles no serializer like controller. (@bf4)
 - [#1618](https://github.com/rails-api/active_model_serializers/issues/1618) Get collection root key for
   empty collection from explicit serializer option, when possible. (@bf4)
 - [#1574](https://github.com/rails-api/active_model_serializers/pull/1574) Provide key translation. (@remear)
diff --git a/lib/action_controller/serialization.rb b/lib/action_controller/serialization.rb
index cc7b8ba7..ff21b831 100644
--- a/lib/action_controller/serialization.rb
+++ b/lib/action_controller/serialization.rb
@@ -33,20 +33,12 @@ module ActionController
         options[:adapter] = false
       end
       serializable_resource = ActiveModel::SerializableResource.new(resource, options)
-      if serializable_resource.serializer?
-        serializable_resource.serialization_scope ||= serialization_scope
-        serializable_resource.serialization_scope_name = _serialization_scope
-        begin
-          # Necessary to ensure we have an adapter for the serializable resource
-          # after it has been figured.
-          # TODO: This logic should be less opaque and probably moved into the SerializableResource.
-          serializable_resource.tap(&:adapter)
-        rescue ActiveModel::Serializer::CollectionSerializer::NoSerializerError
-          resource
-        end
-      else
-        resource
-      end
+      serializable_resource.serialization_scope ||= serialization_scope
+      serializable_resource.serialization_scope_name = _serialization_scope
+      # For compatibility with the JSON renderer: `json.to_json(options) if json.is_a?(String)`.
+      # Otherwise, since `serializable_resource` is not a string, the renderer would call
+      # `to_json` on a String and given odd results, such as `"".to_json #=> '""'`
+      serializable_resource.adapter.is_a?(String) ? serializable_resource.adapter : serializable_resource
     end
 
     # Deprecated
diff --git a/lib/active_model/serializable_resource.rb b/lib/active_model/serializable_resource.rb
index bf0e36f1..b4d962da 100644
--- a/lib/active_model/serializable_resource.rb
+++ b/lib/active_model/serializable_resource.rb
@@ -30,11 +30,19 @@ module ActiveModel
       serializer_opts[:scope_name] = scope_name
     end
 
+    # NOTE: if no adapter is available, returns the resource itself. (i.e. adapter is a no-op)
     def adapter
-      @adapter ||= ActiveModelSerializers::Adapter.create(serializer_instance, adapter_opts)
+      @adapter ||= find_adapter
     end
     alias adapter_instance adapter
 
+    def find_adapter
+      return resource unless serializer?
+      ActiveModelSerializers::Adapter.create(serializer_instance, adapter_opts)
+    rescue ActiveModel::Serializer::CollectionSerializer::NoSerializerError
+      resource
+    end
+
     def serializer_instance
       @serializer_instance ||= serializer.new(resource, serializer_opts)
     end

From ec5dc497b0e029e2da4ad12ad4797f8874b18f16 Mon Sep 17 00:00:00 2001
From: Benjamin Fleischer <github@benjaminfleischer.com>
Date: Mon, 28 Mar 2016 20:10:55 -0500
Subject: [PATCH 2/2] Handle render.ams with nil serializer or adapter

---
 lib/active_model/serializer.rb          |  1 +
 lib/active_model/serializer/null.rb     | 17 +++++++++++++++++
 lib/active_model_serializers/logging.rb |  5 ++++-
 3 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 lib/active_model/serializer/null.rb

diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index 79478abb..e8607845 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -20,6 +20,7 @@ module ActiveModel
   class Serializer
     extend ActiveSupport::Autoload
     autoload :Adapter
+    autoload :Null
     include Configuration
     include Associations
     include Attributes
diff --git a/lib/active_model/serializer/null.rb b/lib/active_model/serializer/null.rb
new file mode 100644
index 00000000..818bbbfa
--- /dev/null
+++ b/lib/active_model/serializer/null.rb
@@ -0,0 +1,17 @@
+module ActiveModel
+  class Serializer
+    class Null < Serializer
+      def attributes(*)
+        {}
+      end
+
+      def associations(*)
+        {}
+      end
+
+      def serializable_hash(*)
+        {}
+      end
+    end
+  end
+end
diff --git a/lib/active_model_serializers/logging.rb b/lib/active_model_serializers/logging.rb
index 2a859c41..943e937e 100644
--- a/lib/active_model_serializers/logging.rb
+++ b/lib/active_model_serializers/logging.rb
@@ -81,7 +81,10 @@ module ActiveModelSerializers
     end
 
     def notify_render_payload
-      { serializer: serializer, adapter: adapter }
+      {
+        serializer: serializer || ActiveModel::Serializer::Null,
+        adapter: adapter || ActiveModelSerializers::Adapter::Null
+      }
     end
 
     private