add errors to conversion

lib/mongo/model/conversion.rb

@@ -28,7 +28,7 @@ def to_rson options = {}
       profile_options = self.class.profiles[profile] || raise("profile :#{profile} not defined for #{self.class}!")
       to_rson profile_options.merge(_profile: profile)
     else
-      options.validate_options! :only, :except, :methods, :_profile
+      options.validate_options! :only, :except, :methods, :errors, :_profile
       child_options = options[:_profile] ? {profile: options[:_profile]} : {}
 
       instance_variables = Mongo::Object.instance_variables(self)
@@ -47,13 +47,19 @@ def to_rson options = {}
       end
 
       methods = options[:methods] ? Array(options[:methods]) : []
-
       methods.each do |method|
         value = send method
         value = Mongo::Object.convert value, :to_rson, child_options
         result[method.to_s] = value
       end
 
+      with_errors = options.include?(:errors) ? options[:errors] : true
+      if with_errors and !(errors = self.errors).empty?
+        stringified_errors = {}
+        errors.each{|k, v| stringified_errors[k.to_s] = v}
+        result['errors'] = stringified_errors
+      end
+
       result
     end
   end

lib/mongo/model/model.rb

@@ -4,7 +4,8 @@ module Mongo::Model
   attr_accessor :_id, :_class
 
   def _id?; !!_id end
-  def new_record?; !_id end
+  def new?; !_id end
+  alias_method :new_record?, :new?
 
   inherited do
     unless is?(Array) or is?(Hash)

spec/conversion_spec.rb

@@ -82,6 +82,24 @@ def build_post_with_comment
       ]
     }
   end
+
+  it "should include errors" do
+    Post.class_eval do
+      validates_presence_of :token
+    end
+
+    post = Post.new text: 'StarCraft releasing soon!'
+    post.valid?.should be_false
+
+    post.to_rson.should == {
+      'text' => 'StarCraft releasing soon!',
+      'errors' => {"token" => ["can't be empty"]}
+    }
+
+    post.to_rson(errors: false).should == {
+      'text' => 'StarCraft releasing soon!'
+    }
+  end
 
   it "to_json" do
     post = build_post_with_comment