From afe786d19ac31ee70228d22cbed4602d9abe320b Mon Sep 17 00:00:00 2001
From: Moritz Lawitschka <me@moritzlawitschka.de>
Date: Tue, 29 Mar 2016 22:03:28 +0200
Subject: [PATCH] Properly deserialize dasherized keys

The JSON API adapater dasherizes every key, but the deserializer left the keys
unaltered. Thus, the client had to send underscored keys in the request body in
order for Rails to properly match sent values to model attributes.

This commit adds automatic key transformation on deserialization. Per default the
deserializer transforms the keys to underscore, but this behaviour can also be
changed by including `key_transform` in the deserializer options.
---
 .../adapter/json_api/deserialization.rb        | 18 ++++++++++++------
 lib/active_model_serializers/key_transform.rb  | 10 ++++++++++
 .../json_api/deserialization_test.rb           | 17 +++++++++++++++--
 3 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/lib/active_model_serializers/adapter/json_api/deserialization.rb b/lib/active_model_serializers/adapter/json_api/deserialization.rb
index f5244355..ff1d3785 100644
--- a/lib/active_model_serializers/adapter/json_api/deserialization.rb
+++ b/lib/active_model_serializers/adapter/json_api/deserialization.rb
@@ -155,7 +155,7 @@ module ActiveModelSerializers
 
         # @api private
         def parse_attributes(attributes, options)
-          attributes
+          transform_keys(attributes, options)
             .map { |(k, v)| { field_key(k, options) => v } }
             .reduce({}, :merge)
         end
@@ -182,23 +182,29 @@ module ActiveModelSerializers
           prefix_key = field_key(assoc_name, options).to_s.singularize
           hash =
             if assoc_data.is_a?(Array)
-              { "#{prefix_key}_ids".to_sym => assoc_data.map { |ri| ri['id'] } }
+              { "#{prefix_key}_ids".to_sym => assoc_data.map { |ri| ri[:id] } }
             else
-              { "#{prefix_key}_id".to_sym => assoc_data ? assoc_data['id'] : nil }
+              { "#{prefix_key}_id".to_sym => assoc_data && assoc_data.is_a?(Hash) ? assoc_data[:id] : nil }
             end
 
           polymorphic = (options[:polymorphic] || []).include?(assoc_name.to_sym)
-          hash["#{prefix_key}_type".to_sym] = assoc_data['type'] if polymorphic
+          hash["#{prefix_key}_type".to_sym] = assoc_data[:type] if polymorphic
 
           hash
         end
 
         # @api private
         def parse_relationships(relationships, options)
-          relationships
-            .map { |(k, v)| parse_relationship(k, v['data'], options) }
+          transform_keys(relationships, options)
+            .map { |(k, v)| parse_relationship(k, v[:data], options) }
             .reduce({}, :merge)
         end
+
+        # @api private
+        def transform_keys(hash, options)
+          transform = options[:key_transform] || :underscore
+          KeyTransform.send(transform, hash)
+        end
       end
     end
   end
diff --git a/lib/active_model_serializers/key_transform.rb b/lib/active_model_serializers/key_transform.rb
index 03cf9cef..cf120547 100644
--- a/lib/active_model_serializers/key_transform.rb
+++ b/lib/active_model_serializers/key_transform.rb
@@ -32,6 +32,16 @@ module ActiveModelSerializers
       hash.deep_transform_keys! { |key| key.to_s.dasherize.to_sym }
     end
 
+    # Transforms keys to underscore.
+    # This is the default case for deserialization in the JsonApi adapter.
+    #
+    # @example:
+    #    "some-key" => "some_key",
+    # @see {https://github.com/rails/rails/blob/master/activesupport/lib/active_support/inflector/methods.rb#L89-L98 ActiveSupport::Inflector.underscore}
+    def underscore(hash)
+      hash.deep_transform_keys! { |key| key.to_s.underscore.to_sym }
+    end
+
     # Returns the hash unaltered
     def unaltered(hash)
       hash
diff --git a/test/action_controller/json_api/deserialization_test.rb b/test/action_controller/json_api/deserialization_test.rb
index 8a57d594..0528dc55 100644
--- a/test/action_controller/json_api/deserialization_test.rb
+++ b/test/action_controller/json_api/deserialization_test.rb
@@ -20,7 +20,10 @@ module ActionController
               'id' => 'zorglub',
               'attributes' => {
                 'title' => 'Ember Hamster',
-                'src' => 'http://example.com/images/productivity.png'
+                'src' => 'http://example.com/images/productivity.png',
+                'image-width' => '200',
+                'imageHeight' => '200',
+                'ImageSize' => '1024'
               },
               'relationships' => {
                 'author' => {
@@ -34,6 +37,12 @@ module ActionController
                     { 'type' => 'comments', 'id' => '1' },
                     { 'type' => 'comments', 'id' => '2' }
                   ]
+                },
+                'related-images' => {
+                  'data' => [
+                    { 'type' => 'image', 'id' => '7' },
+                    { 'type' => 'image', 'id' => '8' }
+                  ]
                 }
               }
             }
@@ -46,9 +55,13 @@ module ActionController
             'id' => 'zorglub',
             'title' => 'Ember Hamster',
             'src' => 'http://example.com/images/productivity.png',
+            'image_width' => '200',
+            'image_height' => '200',
+            'image_size' => '1024',
             'author_id' => nil,
             'photographer_id' => '9',
-            'comment_ids' => %w(1 2)
+            'comment_ids' => %w(1 2),
+            'related_image_ids' => %w(7 8)
           }
 
           assert_equal(expected, response)