Add global config option for key transform

lib/active_model/serializer/configuration.rb

@@ -26,6 +26,7 @@ def config.array_serializer
         # Make JSON API top-level jsonapi member opt-in
         # ref: http://jsonapi.org/format/#document-top-level
         config.jsonapi_include_toplevel_object = false
+        config.key_transform = nil
 
         config.schema_path = 'test/support/schemas'
       end

lib/active_model_serializers/adapter/base.rb

@@ -59,9 +59,20 @@ def default_key_transform
         :unaltered
       end
 
+      # Determines the transform to use in order of precedence:
+      #   serialization context, global config, adapter default.
+      #
+      # @param serialization_context [Object] the SerializationContext
+      # @return [Symbol] the transform to use
+      def key_transform(serialization_context)
+        serialization_context.key_transform ||
+        ActiveModelSerializers.config.key_transform ||
+        default_key_transform
+      end
+
       def transform_key_casing!(value, serialization_context)
         return value unless serialization_context
-        transform = serialization_context.key_transform || default_key_transform
+        transform = key_transform(serialization_context)
         KeyTransform.send(transform, value)
       end
     end

test/adapter/json/key_case_test.rb

@@ -32,6 +32,26 @@ def test_key_transform_default
           }, @adapter.serializable_hash(@options))
         end
 
+        def test_key_transform_global_config
+          mock_request
+          result = with_config(key_transform: :camel_lower) do
+            @adapter.serializable_hash(@options)
+          end
+          assert_equal({
+            blog: { id: 1, specialAttribute: 'neat', articles: nil }
+          }, result)
+        end
+
+        def test_key_transform_serialization_ctx_overrides_global_config
+          mock_request(:camel)
+          result = with_config(key_transform: :camel_lower) do
+            @adapter.serializable_hash(@options)
+          end
+          assert_equal({
+            Blog: { Id: 1, SpecialAttribute: 'neat', Articles: nil }
+          }, result)
+        end
+
         def test_key_transform_undefined
           mock_request(:blam)
           result = nil

test/adapter/json_api/key_case_test.rb

@@ -98,6 +98,78 @@ def test_success_document_key_transform_default
           }, result)
         end
 
+        def test_success_document_key_transform_global_config
+          mock_request
+          result = with_config(key_transform: :camel_lower) do
+            serializer = PostSerializer.new(@post)
+            adapter = ActiveModelSerializers::Adapter::JsonApi.new(serializer)
+            adapter.serializable_hash(@options)
+          end
+          assert_equal({
+            data: {
+              id: '1337',
+              type: 'posts',
+              attributes: {
+                title: 'Title 1',
+                body: 'Body 1',
+                publishAt: @publish_at
+              },
+              relationships: {
+                author: {
+                  data: { id: '1', type: 'authors' }
+                },
+                comments: {
+                  data: [
+                    { id: '7', type: 'comments' },
+                    { id: '12', type: 'comments' }
+                ] }
+              },
+              links: {
+                self: 'http://example.com/posts/1337',
+                postAuthors: 'http://example.com/posts/1337/authors',
+                subscriberComments: 'http://example.com/posts/1337/comments'
+              },
+              meta: { rating: 5, favoriteCount: 10 }
+            }
+          }, result)
+        end
+
+        def test_success_doc_key_transform_serialization_ctx_overrides_global
+          mock_request(:camel)
+          result = with_config(key_transform: :camel_lower) do
+            serializer = PostSerializer.new(@post)
+            adapter = ActiveModelSerializers::Adapter::JsonApi.new(serializer)
+            adapter.serializable_hash(@options)
+          end
+          assert_equal({
+            Data: {
+              Id: '1337',
+              Type: 'posts',
+              Attributes: {
+                Title: 'Title 1',
+                Body: 'Body 1',
+                PublishAt: @publish_at
+              },
+              Relationships: {
+                Author: {
+                  Data: { Id: '1', Type: 'authors' }
+                },
+                Comments: {
+                  Data: [
+                    { Id: '7', Type: 'comments' },
+                    { Id: '12', Type: 'comments' }
+                ] }
+              },
+              Links: {
+                Self: 'http://example.com/posts/1337',
+                PostAuthors: 'http://example.com/posts/1337/authors',
+                SubscriberComments: 'http://example.com/posts/1337/comments'
+              },
+              Meta: { Rating: 5, FavoriteCount: 10 }
+            }
+          }, result)
+        end
+
         def test_success_document_key_transform_dashed
           mock_request(:dashed)
           serializer = PostSerializer.new(@post)
@@ -245,22 +317,76 @@ def test_success_document_key_transform_camel_lower
 
         def test_error_document_key_transform_default
           mock_request
-
           resource = ModelWithErrors.new
           resource.errors.add(:published_at, 'must be in the future')
           resource.errors.add(:title, 'must be longer')
-
           serializer = ActiveModel::Serializer::ErrorSerializer.new(resource)
           adapter = ActiveModelSerializers::Adapter::JsonApi.new(serializer)
           result = adapter.serializable_hash(@options)
-
           expected_errors_object =
             { :errors =>
               [
-                { :source => { :pointer => '/data/attributes/published_at' }, :detail => 'must be in the future' },
-                { :source => { :pointer => '/data/attributes/title' }, :detail => 'must be longer' }
+                {
+                  :source => { :pointer => '/data/attributes/published_at' },
+                  :detail => 'must be in the future' },
+                {
+                  :source => { :pointer => '/data/attributes/title' },
+                  :detail => 'must be longer'
+                }
               ]
-          }
+            }
+          assert_equal expected_errors_object, result
+        end
+
+        def test_error_document_key_transform_global_config
+          mock_request
+          result = with_config(key_transform: :camel) do
+            resource = ModelWithErrors.new
+            resource.errors.add(:published_at, 'must be in the future')
+            resource.errors.add(:title, 'must be longer')
+            serializer = ActiveModel::Serializer::ErrorSerializer.new(resource)
+            adapter = ActiveModelSerializers::Adapter::JsonApi.new(serializer)
+            adapter.serializable_hash(@options)
+          end
+          expected_errors_object =
+            { :Errors =>
+              [
+                {
+                  :Source => { :Pointer => '/data/attributes/published_at' },
+                  :Detail => 'must be in the future'
+                },
+                {
+                  :Source => { :Pointer => '/data/attributes/title' },
+                  :Detail => 'must be longer'
+                }
+              ]
+            }
+          assert_equal expected_errors_object, result
+        end
+
+        def test_error_document_key_transform_serialization_ctx_overrides_global
+          mock_request(:camel)
+          result = with_config(key_transform: :camel_lower) do
+            resource = ModelWithErrors.new
+            resource.errors.add(:published_at, 'must be in the future')
+            resource.errors.add(:title, 'must be longer')
+            serializer = ActiveModel::Serializer::ErrorSerializer.new(resource)
+            adapter = ActiveModelSerializers::Adapter::JsonApi.new(serializer)
+            adapter.serializable_hash(@options)
+          end
+          expected_errors_object =
+            { :Errors =>
+              [
+                {
+                  :Source => { :Pointer => '/data/attributes/published_at' },
+                  :Detail => 'must be in the future'
+                },
+                {
+                  :Source => { :Pointer => '/data/attributes/title' },
+                  :Detail => 'must be longer'
+                }
+              ]
+            }
           assert_equal expected_errors_object, result
         end
 
@@ -278,8 +404,14 @@ def test_error_document_key_transform_dashed
           expected_errors_object =
             { :errors =>
               [
-                { :source => { :pointer => '/data/attributes/published_at' }, :detail => 'must be in the future' },
-                { :source => { :pointer => '/data/attributes/title' }, :detail => 'must be longer' }
+                {
+                  :source => { :pointer => '/data/attributes/published_at' },
+                  :detail => 'must be in the future'
+                },
+                {
+                  :source => { :pointer => '/data/attributes/title' },
+                  :detail => 'must be longer'
+                }
               ]
           }
           assert_equal expected_errors_object, result