Fix deserialization

Author: remear

lib/active_model_serializers/adapter/json_api/deserialization.rb

@@ -182,28 +182,28 @@ def parse_relationship(assoc_name, assoc_data, options)
           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.is_a?(Hash) ? assoc_data[:id] : nil }
+              { "#{prefix_key}_id".to_sym => assoc_data ? 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)
           transform_keys(relationships, options)
-            .map { |(k, v)| parse_relationship(k, v[:data], 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)
+          transform = options[:transform] || :underscore
+          Transform.send(transform, hash)
         end
       end
     end

lib/active_model_serializers/transform.rb

@@ -47,14 +47,19 @@ def dash(value)
       end
     end
 
-    # Transforms keys to underscore.
+    # Transforms values to underscore_case.
     # 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 }
+    def underscore(value)
+      case value
+      when Hash then value.deep_transform_keys! { |key| underscore(key) }
+      when Symbol then underscore(value.to_s).to_sym
+      when String then value.underscore
+      else value
+      end
     end
 
     # Returns the value unaltered