Encapsulate serialization in ActiveModel::SerializableResource

Usage: ActiveModel::SerializableResource.serialize(resource, options)

lib/action_controller/serialization.rb

@@ -6,7 +6,8 @@ module ActionController
 
     include ActionController::Renderers
 
-    ADAPTER_OPTION_KEYS = [:include, :fields, :adapter]
+    # Deprecated
+    ADAPTER_OPTION_KEYS = ActiveModel::SerializableResource::ADAPTER_OPTION_KEYS
 
     included do
       class_attribute :_serialization_scope
@@ -18,47 +19,55 @@ module ActionController
         respond_to?(_serialization_scope, true)
     end
 
-    def get_serializer(resource)
-      @_serializer ||= @_serializer_opts.delete(:serializer)
-      @_serializer ||= ActiveModel::Serializer.serializer_for(resource)
-
-      if @_serializer_opts.key?(:each_serializer)
-        @_serializer_opts[:serializer] = @_serializer_opts.delete(:each_serializer)
+    def get_serializer(resource, options = {})
+      if ! use_adapter?
+        warn "ActionController::Serialization#use_adapter? has been removed. "\
+          "Please pass 'adapter: false' or see ActiveSupport::SerializableResource#serialize"
+        options[:adapter] = false
+      end
+      ActiveModel::SerializableResource.serialize(resource, options) do |serializable_resource|
+        if serializable_resource.serializer?
+          serializable_resource.serialization_scope ||= serialization_scope
+          serializable_resource.serialization_scope_name = _serialization_scope
+          begin
+            serializable_resource.adapter
+          rescue ActiveModel::Serializer::ArraySerializer::NoSerializerError
+            resource
+          end
+        else
+          resource
+        end
       end
-
-      @_serializer
     end
 
+    # Deprecated
     def use_adapter?
-      !(@_adapter_opts.key?(:adapter) && !@_adapter_opts[:adapter])
+      true
     end
 
     [:_render_option_json, :_render_with_renderer_json].each do |renderer_method|
       define_method renderer_method do |resource, options|
-        @_adapter_opts, @_serializer_opts =
-          options.partition { |k, _| ADAPTER_OPTION_KEYS.include? k }.map { |h| Hash[h] }
-
-        if use_adapter? && (serializer = get_serializer(resource))
-          @_serializer_opts[:scope] ||= serialization_scope
-          @_serializer_opts[:scope_name] = _serialization_scope
-
-          begin
-            serialized = serializer.new(resource, @_serializer_opts)
-          rescue ActiveModel::Serializer::ArraySerializer::NoSerializerError
-          else
-            resource = ActiveModel::Serializer::Adapter.create(serialized, @_adapter_opts)
-          end
-        end
-
-        super(resource, options)
+        serializable_resource = get_serializer(resource, options)
+        super(serializable_resource, options)
       end
     end
 
+    # Tries to rescue the exception by looking up and calling a registered handler.
+    #
+    # Possibly Deprecated
+    # TODO: Either Decorate 'exception' and define #handle_error where it is serialized
+    # For example:
+    #   class ExceptionModel
+    #     include ActiveModel::Serialization
+    #     def initialize(exception)
+    #     # etc
+    #   end
+    #   def handle_error(exception)
+    #     exception_model = ActiveModel::Serializer.build_exception_model({ errors: ['Internal Server Error'] })
+    #     render json: exception_model, status: :internal_server_error
+    #   end
+    # OR remove method as it doesn't do anything right now.
     def rescue_with_handler(exception)
-      @_serializer = nil
-      @_serializer_opts = nil
-      @_adapter_opts = nil
-
       super(exception)
     end
 

lib/active_model/serializable_resource.rb

@@ -0,0 +1,82 @@
+require "set"
+module ActiveModel
+  class SerializableResource
+
+    ADAPTER_OPTION_KEYS = Set.new([:include, :fields, :adapter])
+
+    def initialize(resource, options = {})
+      @resource = resource
+      @adapter_opts, @serializer_opts =
+        options.partition { |k, _| ADAPTER_OPTION_KEYS.include? k }.map { |h| Hash[h] }
+    end
+
+    delegate :serializable_hash, :as_json, :to_json, to: :adapter
+
+    # Primary interface to building a serializer (with adapter)
+    # If no block is given,
+    # returns the serializable_resource, ready for #as_json/#to_json/#serializable_hash.
+    # Otherwise, yields the serializable_resource and
+    # returns the contents of the block
+    def self.serialize(resource, options = {})
+      serializable_resource = SerializableResource.new(resource, options)
+      if block_given?
+        yield serializable_resource
+      else
+        serializable_resource
+      end
+    end
+
+    def serialization_scope=(scope)
+      serializer_opts[:scope] = scope
+    end
+
+    def serialization_scope
+      serializer_opts[:scope]
+    end
+
+    def serialization_scope_name=(scope_name)
+      serializer_opts[:scope_name] = scope_name
+    end
+
+    def adapter
+      @adapter ||= ActiveModel::Serializer::Adapter.create(serializer_instance, adapter_opts)
+    end
+    alias_method :adapter_instance, :adapter
+
+    def serializer_instance
+      @serializer_instance ||= serializer.new(resource, serializer_opts)
+    end
+
+    # Get serializer either explicitly :serializer or implicitly from resource
+    # Remove :serializer key from serializer_opts
+    # Replace :serializer key with :each_serializer if present
+    def serializer
+      @serializer ||=
+        begin
+          @serializer = serializer_opts.delete(:serializer)
+          @serializer ||= ActiveModel::Serializer.serializer_for(resource)
+
+          if serializer_opts.key?(:each_serializer)
+            serializer_opts[:serializer] = serializer_opts.delete(:each_serializer)
+          end
+          @serializer
+        end
+    end
+    alias_method :serializer_class, :serializer
+
+    # True when no explicit adapter given, or explicit appear is truthy (non-nil)
+    # False when explicit adapter is falsy (nil or false)
+    def use_adapter?
+      !(adapter_opts.key?(:adapter) && !adapter_opts[:adapter])
+    end
+
+    def serializer?
+      use_adapter? && !!(serializer)
+    end
+
+    private
+
+    attr_reader :resource, :adapter_opts, :serializer_opts
+
+  end
+end

lib/active_model_serializers.rb

@@ -3,6 +3,7 @@ require 'active_model/serializer/version'
 require 'active_model/serializer'
 require 'active_model/serializer/fieldset'
 require 'active_model/serializer/railtie'
+require 'active_model/serializable_resource'
 
 begin
   require 'action_controller'