Make serializers serializable, step 1.

CHANGELOG.md

@@ -3,6 +3,8 @@
 Breaking changes:
 
 Features:
+- [#1494](https://github.com/rails-api/active_model_serializers/pull/1494) Make serializers serializalbe
+  (using the Attributes adapter by default). (@bf4)
 - [#1550](https://github.com/rails-api/active_model_serializers/pull/1550) Add
   Rails url_helpers to `SerializationContext` for use in links. (@remear, @bf4)
 - [#1004](https://github.com/rails-api/active_model_serializers/pull/1004) JSON API errors object implementation.

lib/active_model/serializer.rb

@@ -126,6 +126,57 @@ module ActiveModel
       true
     end
 
+    # @return [Hash] containing the attributes and first level
+    # associations, similar to how ActiveModel::Serializers::JSON is used
+    # in ActiveRecord::Base.
+    #
+    # TODO: Move to here the Attributes adapter logic for
+    # +serializable_hash_for_single_resource(options)+
+    # and include <tt>ActiveModel::Serializers::JSON</tt>.
+    # So that the below is true:
+    #   @param options [nil, Hash] The same valid options passed to `serializable_hash`
+    #      (:only, :except, :methods, and :include).
+    #
+    #     See
+    #     https://github.com/rails/rails/blob/v5.0.0.beta2/activemodel/lib/active_model/serializers/json.rb#L17-L101
+    #     https://github.com/rails/rails/blob/v5.0.0.beta2/activemodel/lib/active_model/serialization.rb#L85-L123
+    #     https://github.com/rails/rails/blob/v5.0.0.beta2/activerecord/lib/active_record/serialization.rb#L11-L17
+    #     https://github.com/rails/rails/blob/v5.0.0.beta2/activesupport/lib/active_support/core_ext/object/json.rb#L147-L162
+    #
+    #   @example
+    #     # The :only and :except options can be used to limit the attributes included, and work
+    #     # similar to the attributes method.
+    #     serializer.as_json(only: [:id, :name])
+    #     serializer.as_json(except: [:id, :created_at, :age])
+    #
+    #     # To include the result of some method calls on the model use :methods:
+    #     serializer.as_json(methods: :permalink)
+    #
+    #     # To include associations use :include:
+    #     serializer.as_json(include: :posts)
+    #     # Second level and higher order associations work as well:
+    #     serializer.as_json(include: { posts: { include: { comments: { only: :body } }, only: :title } })
+    def serializable_hash(adapter_opts = nil)
+      adapter_opts ||= {}
+      adapter_opts = { include: '*', adapter: :attributes }.merge!(adapter_opts)
+      adapter = ActiveModelSerializers::Adapter.create(self, adapter_opts)
+      adapter.serializable_hash(adapter_opts)
+    end
+    alias to_hash serializable_hash
+    alias to_h serializable_hash
+
+    # @see #serializable_hash
+    # TODO: When moving attributes adapter logic here, @see #serializable_hash
+    # So that the below is true:
+    #   @param options [nil, Hash] The same valid options passed to `as_json`
+    #      (:root, :only, :except, :methods, and :include).
+    #   The default for `root` is nil.
+    #   The default value for include_root is false. You can change it to true if the given
+    #   JSON string includes a single root node.
+    def as_json(adapter_opts = nil)
+      serializable_hash(adapter_opts)
+    end
+
     # Used by adapter as resource root.
     def json_key
       root || object.class.model_name.to_s.underscore

test/serializers/serialization_test.rb

@@ -0,0 +1,55 @@
+module ActiveModel
+  class Serializer
+    class SerializationTest < ActiveSupport::TestCase
+      class Blog < ActiveModelSerializers::Model
+        attr_accessor :id, :name, :authors
+      end
+      class Author < ActiveModelSerializers::Model
+        attr_accessor :id, :name
+      end
+      class BlogSerializer < ActiveModel::Serializer
+        attributes :id
+        attribute :name, key: :title
+
+        has_many :authors
+      end
+      class AuthorSerializer < ActiveModel::Serializer
+        attributes :id, :name
+      end
+
+      setup do
+        @authors = [Author.new(id: 1, name: 'Blog Author')]
+        @blog = Blog.new(id: 2, name: 'The Blog', authors: @authors)
+        @serializer_instance = BlogSerializer.new(@blog)
+        @serializable = ActiveModel::SerializableResource.new(@blog, serializer: BlogSerializer, adapter: :attributes)
+        @expected_hash = { id: 2, title: 'The Blog', authors: [{ id: 1, name: 'Blog Author' }] }
+        @expected_json = '{"id":2,"title":"The Blog","authors":[{"id":1,"name":"Blog Author"}]}'
+      end
+
+      test '#serializable_hash is the same as generated by the attributes adapter' do
+        assert_equal @serializable.serializable_hash, @serializer_instance.serializable_hash
+        assert_equal @expected_hash, @serializer_instance.serializable_hash
+      end
+
+      test '#as_json is the same as generated by the attributes adapter' do
+        assert_equal @serializable.as_json, @serializer_instance.as_json
+        assert_equal @expected_hash, @serializer_instance.as_json
+      end
+
+      test '#to_json is the same as generated by the attributes adapter' do
+        assert_equal @serializable.to_json, @serializer_instance.to_json
+        assert_equal @expected_json, @serializer_instance.to_json
+      end
+
+      test '#to_h is an alias for #serializable_hash' do
+        assert_equal @serializable.serializable_hash, @serializer_instance.to_h
+        assert_equal @expected_hash, @serializer_instance.to_h
+      end
+
+      test '#to_hash is an alias for #serializable_hash' do
+        assert_equal @serializable.serializable_hash, @serializer_instance.to_hash
+        assert_equal @expected_hash, @serializer_instance.to_hash
+      end
+    end
+  end
+end