resource.rb in alba-1.1.0

- old
+ new

@@ -26,13 +26,15 @@
     module InstanceMethods
       attr_reader :object, :params
 
       # @param object [Object] the object to be serialized
       # @param params [Hash] user-given Hash for arbitrary data
-      def initialize(object, params: {})
+      # @param within [Hash] determines what associations to be serialized. If not set, it serializes all associations.
+      def initialize(object, params: {}, within: true)
         @object = object
         @params = params.freeze
+        @within = within
         DSLS.each_key { |name| instance_variable_set("@#{name}", self.class.public_send(name)) }
       end
 
       # Serialize object into JSON string
       #
@@ -128,12 +130,32 @@
         when Symbol
           object.public_send attribute
         when Proc
           instance_exec(object, &attribute)
         when Alba::One, Alba::Many
-          attribute.to_hash(object, params: params)
+          within = check_within
+          return unless within
+
+          attribute.to_hash(object, params: params, within: within)
         else
           raise ::Alba::Error, "Unsupported type of attribute: #{attribute.class}"
+        end
+      end
+
+      def check_within
+        case @within
+        when Hash # Traverse within tree
+          @within.fetch(_key.to_sym, nil)
+        when Array # within tree ends with Array
+          @within.find { |item| item.to_sym == _key.to_sym } # Check if at least one item in the array matches current resource
+        when Symbol # within tree could end with Symbol
+          @within == _key.to_sym # Check if the symbol matches current resource
+        when true # In this case, Alba serializes all associations.
+          true
+        when nil, false # In these cases, Alba stops serialization here.
+          false
+        else
+          raise Alba::Error, "Unknown type for within option: #{@within.class}"
         end
       end
 
       def collection?
         @object.is_a?(Enumerable)