added initial changes

lib/fast_jsonapi/object_serializer.rb

@@ -50,7 +50,7 @@ module FastJsonapi
 
       return serializable_hash unless @resource
 
-      serializable_hash[:data] = self.class.record_hash(@resource, @fieldsets[self.class.record_type.to_sym], @includes, @params)
+      serializable_hash[:data] = self.class.record_hash(@resource, @fieldsets[self.class.record_type.to_sym], @includes, @params, @optional)
       serializable_hash[:included] = self.class.get_included_records(@resource, @includes, @known_included_objects, @fieldsets, @params) if @includes.present?
       serializable_hash
     end
@@ -62,7 +62,7 @@ module FastJsonapi
       included = []
       fieldset = @fieldsets[self.class.record_type.to_sym]
       @resource.each do |record|
-        data << self.class.record_hash(record, fieldset, @includes, @params)
+        data << self.class.record_hash(record, fieldset, @includes, @params, @optional)
         included.concat self.class.get_included_records(record, @includes, @known_included_objects, @fieldsets, @params) if @includes.present?
       end
 
@@ -92,6 +92,11 @@ module FastJsonapi
         @includes = options[:include].reject(&:blank?).map(&:to_sym)
         self.class.validate_includes!(@includes)
       end
+
+      @optional = options[:optional] || []
+      raise ArgumentError, '`optional` option passed to serializer must be an array' unless @optional.is_a?(Array)
+
+      @optional.map! { |x| x.to_s.to_sym }
     end
 
     def deep_symbolize(collection)
@@ -216,6 +221,13 @@ module FastJsonapi
             options: options
           )
         end
+
+        key = run_key_transform(attributes_list[0])
+        attributes_to_serialize[key] = Attribute.new(
+          key: key,
+          method: block || attributes_list[0],
+          options: options
+        )        
       end
 
       alias_method :attribute, :attributes

lib/fast_jsonapi/scalar.rb

@@ -1,15 +1,16 @@
 module FastJsonapi
   class Scalar
-    attr_reader :key, :method, :conditional_proc
+    attr_reader :key, :method, :conditional_proc, :optional
 
     def initialize(key:, method:, options: {})
       @key = key
       @method = method
       @conditional_proc = options[:if]
+      @optional = options[:optional] || false
     end
 
-    def serialize(record, serialization_params, output_hash)
-      if conditionally_allowed?(record, serialization_params)
+    def serialize(record, serialization_params, output_hash, allowed_optionals)
+      if conditionally_allowed?(record, serialization_params, allowed_optionals)
         if method.is_a?(Proc)
           output_hash[key] = FastJsonapi.call_proc(method, record, serialization_params)
         else
@@ -18,7 +19,9 @@ module FastJsonapi
       end
     end
 
-    def conditionally_allowed?(record, serialization_params)
+    def conditionally_allowed?(record, serialization_params, allowed_optionals)
+      return false if optional.present? && !allowed_optionals.include?(@key)
+
       if conditional_proc.present?
         FastJsonapi.call_proc(conditional_proc, record, serialization_params)
       else

lib/fast_jsonapi/serialization_core.rb

@@ -41,13 +41,13 @@ module FastJsonapi
         end
       end
 
-      def attributes_hash(record, fieldset = nil, params = {})
+      def attributes_hash(record, fieldset = nil, params = {}, optional= [])
         attributes = attributes_to_serialize
         attributes = attributes.slice(*fieldset) if fieldset.present?
         attributes = {} if fieldset == []
 
         attributes.each_with_object({}) do |(_k, attribute), hash|
-          attribute.serialize(record, params, hash)
+          attribute.serialize(record, params, hash, optional)
         end
       end
 
@@ -66,12 +66,12 @@ module FastJsonapi
         FastJsonapi.call_proc(meta_to_serialize, record, params)
       end
 
-      def record_hash(record, fieldset, includes_list, params = {})
+      def record_hash(record, fieldset, includes_list, params = {}, optional = [])
         if cache_store_instance
           cache_opts = record_cache_options(cache_store_options, fieldset, includes_list, params)
           record_hash = cache_store_instance.fetch(record, **cache_opts) do
             temp_hash = id_hash(id_from_record(record, params), record_type, true)
-            temp_hash[:attributes] = attributes_hash(record, fieldset, params) if attributes_to_serialize.present?
+            temp_hash[:attributes] = attributes_hash(record, fieldset, params, optional) if attributes_to_serialize.present?
             temp_hash[:relationships] = relationships_hash(record, cachable_relationships_to_serialize, fieldset, includes_list, params) if cachable_relationships_to_serialize.present?
             temp_hash[:links] = links_hash(record, params) if data_links.present?
             temp_hash
@@ -79,7 +79,7 @@ module FastJsonapi
           record_hash[:relationships] = (record_hash[:relationships] || {}).merge(relationships_hash(record, uncachable_relationships_to_serialize, fieldset, includes_list, params)) if uncachable_relationships_to_serialize.present?
         else
           record_hash = id_hash(id_from_record(record, params), record_type, true)
-          record_hash[:attributes] = attributes_hash(record, fieldset, params) if attributes_to_serialize.present?
+          record_hash[:attributes] = attributes_hash(record, fieldset, params, optional) if attributes_to_serialize.present?
           record_hash[:relationships] = relationships_hash(record, nil, fieldset, includes_list, params) if relationships_to_serialize.present?
           record_hash[:links] = links_hash(record, params) if data_links.present?
         end