Allow attribute aliasing

lib/active_model/serializer.rb

@@ -103,7 +103,7 @@ module ActiveModel
     end
 
     class_attribute :_attributes
-    self._attributes = Set.new
+    self._attributes = {}
 
     class_attribute :_associations
     self._associations = []
@@ -116,7 +116,15 @@ module ActiveModel
     class << self
       # Define attributes to be used in the serialization.
       def attributes(*attrs)
-        self._attributes += attrs
+        self._attributes = _attributes.dup
+
+        attrs.each do |attr|
+          self._attributes[attr] = attr
+        end
+      end
+
+      def attribute(attr, options={})
+        self._attributes = _attributes.merge(attr => options[:key] || attr)
       end
 
       def associate(klass, attrs) #:nodoc:
@@ -192,9 +200,9 @@ module ActiveModel
         klass = model_class
         columns = klass.columns_hash
 
-        attrs = _attributes.inject({}) do |hash, name|
+        attrs = _attributes.inject({}) do |hash, (name,key)|
           column = columns[name]
-          hash.merge name => column[:type]
+          hash.merge key => column[:type]
         end
 
         associations = _associations.inject({}) do |hash, association|
@@ -299,8 +307,8 @@ module ActiveModel
     def attributes
       hash = {}
 
-      _attributes.each do |name|
+      _attributes.each do |name,key|
-        hash[name] = @object.read_attribute_for_serialization(name)
+        hash[key] = @object.read_attribute_for_serialization(name)
       end
 
       hash

test/serializer_test.rb

@@ -509,6 +509,26 @@ class SerializerTest < ActiveModel::TestCase
     }, serializer.as_json)
   end
 
+  def test_attribute_key
+    serializer_class = Class.new(ActiveModel::Serializer) do
+      root :user
+
+      attribute :first_name, :key => :firstName
+      attribute :last_name, :key => :lastName
+      attribute :password
+    end
+
+    serializer = serializer_class.new(User.new, nil)
+
+    assert_equal({
+      :user => {
+        :firstName => "Jose",
+        :lastName => "Valim",
+        :password => "oh noes yugive my password"
+      }
+    }, serializer.as_json)
+  end
+
   def setup_model
     Class.new do
       class << self