1 files changed, 33 insertions, 27 deletions

diff --git a/activemodel/lib/active_model/serializer.rb b/activemodel/lib/active_model/serializer.rb
index 7a55921e85..5b603bdbd7 100644
--- a/activemodel/lib/active_model/serializer.rb
+++ b/activemodel/lib/active_model/serializer.rb
@@ -8,6 +8,9 @@ module ActiveModel
     def initialize(serializable, options = nil)
       @serializable = serializable
       @options = options ? options.dup : {}
+
+      @options[:only] = Array.wrap(@options[:only]).map { |n| n.to_s }
+      @options[:except] = Array.wrap(@options[:except]).map { |n| n.to_s }
     end
 
     def serialize
@@ -18,37 +21,40 @@ module ActiveModel
       serialize(&block)
     end
 
-    protected
-      def serializable_attribute_names
-        attribute_names = @serializable.attributes.keys
-
-        if options[:only]
-          only = Array.wrap(options[:only]).map { |n| n.to_s }
-          attribute_names &= only
-        elsif options[:except]
-          except = Array.wrap(options[:except]).map { |n| n.to_s }
-          attribute_names -= except
-        end
-
-        attribute_names
+    # To replicate the behavior in ActiveRecord#attributes,
+    # <tt>:except</tt> takes precedence over <tt>:only</tt>.  If <tt>:only</tt> is not set
+    # for a N level model but is set for the N+1 level models,
+    # then because <tt>:except</tt> is set to a default value, the second
+    # level model can have both <tt>:except</tt> and <tt>:only</tt> set.  So if
+    # <tt>:only</tt> is set, always delete <tt>:except</tt>.
+    def serializable_attribute_names
+      attribute_names = @serializable.attributes.keys.sort
+
+      if options[:only].any?
+        attribute_names &= options[:only]
+      elsif options[:except].any?
+        attribute_names -= options[:except]
       end
 
-      def serializable_method_names
-        Array.wrap(options[:methods]).inject([]) do |methods, name|
-          methods << name if @serializable.respond_to?(name.to_s)
-          methods
-        end
-      end
+      attribute_names
+    end
 
-      def serializable_names
-        serializable_attribute_names + serializable_method_names
+    def serializable_method_names
+      Array.wrap(options[:methods]).inject([]) do |methods, name|
+        methods << name if @serializable.respond_to?(name.to_s)
+        methods
       end
+    end
 
-      def serializable_hash
-        serializable_names.inject({}) { |hash, name|
-          hash[name] = @serializable.send(name)
-          hash
-        }
-      end
+    def serializable_names
+      serializable_attribute_names + serializable_method_names
+    end
+
+    def serializable_hash
+      serializable_names.inject({}) { |hash, name|
+        hash[name] = @serializable.send(name)
+        hash
+      }
+    end
   end
 end