Make serializer lookup configurable (#1757)

test/action_controller/lookup_proc_test.rb

@@ -0,0 +1,49 @@
+require 'test_helper'
+
+module ActionController
+  module Serialization
+    class LookupProcTest < ActionController::TestCase
+      module Api
+        module V3
+          class PostCustomSerializer < ActiveModel::Serializer
+            attributes :title, :body
+
+            belongs_to :author
+          end
+
+          class AuthorCustomSerializer < ActiveModel::Serializer
+            attributes :name
+          end
+
+          class LookupProcTestController < ActionController::Base
+            def implicit_namespaced_serializer
+              author = Author.new(name: 'Bob')
+              post = Post.new(title: 'New Post', body: 'Body', author: author)
+
+              render json: post
+            end
+          end
+        end
+      end
+
+      tests Api::V3::LookupProcTestController
+
+      test 'implicitly uses namespaced serializer' do
+        controller_namespace = lambda do |resource_class, _parent_serializer_class, namespace|
+          "#{namespace}::#{resource_class}CustomSerializer" if namespace
+        end
+
+        with_prepended_lookup(controller_namespace) do
+          get :implicit_namespaced_serializer
+
+          assert_serializer Api::V3::PostCustomSerializer
+
+          expected = { 'title' => 'New Post', 'body' => 'Body', 'author' => { 'name' => 'Bob' } }
+          actual = JSON.parse(@response.body)
+
+          assert_equal expected, actual
+        end
+      end
+    end
+  end
+end

test/action_controller/namespace_lookup_test.rb

@@ -15,6 +15,16 @@ module ActionController
           end
         end
 
+        module VHeader
+          class BookSerializer < ActiveModel::Serializer
+            attributes :title, :body
+
+            def body
+              'header'
+            end
+          end
+        end
+
         module V3
           class BookSerializer < ActiveModel::Serializer
             attributes :title, :body
@@ -92,6 +102,14 @@ module ActionController
               book = Book.new(title: 'New Post', body: 'Body')
               render json: book
             end
+
+            def namespace_set_by_request_headers
+              book = Book.new(title: 'New Post', body: 'Body')
+              version_from_header = request.headers['X-API_VERSION']
+              namespace = "ActionController::Serialization::NamespaceLookupTest::#{version_from_header}"
+
+              render json: book, namespace: namespace
+            end
           end
         end
       end
@@ -102,6 +120,13 @@ module ActionController
         @test_namespace = self.class.parent
       end
 
+      test 'uses request headers to determine the namespace' do
+        request.env['X-API_VERSION'] = 'Api::VHeader'
+        get :namespace_set_by_request_headers
+
+        assert_serializer Api::VHeader::BookSerializer
+      end
+
       test 'implicitly uses namespaced serializer' do
         get :implicit_namespaced_serializer
 

test/benchmark/bm_lookup_chain.rb

@@ -0,0 +1,83 @@
+require_relative './benchmarking_support'
+require_relative './app'
+
+time = 10
+disable_gc = true
+ActiveModelSerializers.config.key_transform = :unaltered
+
+module AmsBench
+  module Api
+    module V1
+      class PrimaryResourceSerializer < ActiveModel::Serializer
+        attributes :title, :body
+
+        has_many :has_many_relationships
+      end
+
+      class HasManyRelationshipSerializer < ActiveModel::Serializer
+        attribute :body
+      end
+    end
+  end
+  class PrimaryResourceSerializer < ActiveModel::Serializer
+    attributes :title, :body
+
+    has_many :has_many_relationships
+
+    class HasManyRelationshipSerializer < ActiveModel::Serializer
+      attribute :body
+    end
+  end
+end
+
+resource = PrimaryResource.new(
+  id: 1,
+  title: 'title',
+  body: 'body',
+  has_many_relationships: [
+    HasManyRelationship.new(id: 1, body: 'body1'),
+    HasManyRelationship.new(id: 2, body: 'body1')
+  ]
+)
+
+serialization = lambda do
+  ActiveModelSerializers::SerializableResource.new(resource, serializer: AmsBench::PrimaryResourceSerializer).as_json
+  ActiveModelSerializers::SerializableResource.new(resource, namespace: AmsBench::Api::V1).as_json
+  ActiveModelSerializers::SerializableResource.new(resource).as_json
+end
+
+def clear_cache
+  AmsBench::PrimaryResourceSerializer.serializers_cache.clear
+  AmsBench::Api::V1::PrimaryResourceSerializer.serializers_cache.clear
+  ActiveModel::Serializer.serializers_cache.clear
+end
+
+configurable = lambda do
+  clear_cache
+  Benchmark.ams('Configurable Lookup Chain', time: time, disable_gc: disable_gc, &serialization)
+end
+
+old = lambda do
+  clear_cache
+  module ActiveModel
+    class Serializer
+      def self.serializer_lookup_chain_for(klass, namespace = nil)
+        chain = []
+
+        resource_class_name = klass.name.demodulize
+        resource_namespace = klass.name.deconstantize
+        serializer_class_name = "#{resource_class_name}Serializer"
+
+        chain.push("#{namespace}::#{serializer_class_name}") if namespace
+        chain.push("#{name}::#{serializer_class_name}") if self != ActiveModel::Serializer
+        chain.push("#{resource_namespace}::#{serializer_class_name}")
+        chain
+      end
+    end
+  end
+
+  Benchmark.ams('Old Lookup Chain (v0.10)', time: time, disable_gc: disable_gc, &serialization)
+end
+
+configurable.call
+old.call

test/support/serialization_testing.rb

@@ -17,6 +17,14 @@ module SerializationTesting
     ActiveModelSerializers.config.jsonapi_namespace_separator = original_separator
   end
 
+  def with_prepended_lookup(lookup_proc)
+    original_lookup = ActiveModelSerializers.config.serializer_lookup_cahin
+    ActiveModelSerializers.config.serializer_lookup_chain.unshift lookup_proc
+    yield
+  ensure
+    ActiveModelSerializers.config.serializer_lookup_cahin = original_lookup
+  end
+
   # Aliased as :with_configured_adapter to clarify that
   # this method tests the configured adapter.
   # When not testing configuration, it may be preferable