Support conditions in link statements

lib/active_model/serializer/link.rb

@@ -0,0 +1,21 @@
+require 'active_model/serializer/field'
+
+module ActiveModel
+  class Serializer
+    # Holds all the data about an serializer link
+    #
+    # @example
+    #   class PostSerializer < ActiveModel::Serializer
+    #     link :callback, if: :internal? do
+    #       object.callback_link
+    #     end
+    #
+    #     def internal?
+    #       instance_options[:internal] == true
+    #     end
+    #   end
+    #
+    class Link < Field
+    end
+  end
+end