Added presenter method attr_expose to AR

README.md

@@ -32,6 +32,9 @@ Say, for example, you have a basic Food model:
 ```ruby
 class Food < ActiveRecord::Base
   include RocketPants::Cacheable
+
+  # Only expose the following attributes in the API JSON response
+  attr_expose :name, :calories
 end
 ```
 

lib/rocket_pants.rb

@@ -22,6 +22,9 @@ module RocketPants
   autoload :Cacheable,       'rocket_pants/cacheable'
   autoload :CacheMiddleware, 'rocket_pants/cache_middleware'
 
+  # Model
+  autoload :Presenter,        'rocket_pants/presenter'
+
   # Helpers for various testing frameworks.
   autoload :TestHelper,      'rocket_pants/test_helper'
   autoload :RSpecMatchers,   'rocket_pants/rspec_matchers'

lib/rocket_pants/base.rb

@@ -28,6 +28,7 @@ class Base < ActionController::Metal
       ActionController::Rescue,
       ErrorHandling,
       Rescuable,
+      Presenter,
       JSONP
       # FormatVerification # TODO: Implement Format Verification
     ].compact

lib/rocket_pants/presenter.rb

@@ -0,0 +1,30 @@
+# Provides a way of selecting certain field attributes to present in the JSON response
+module RocketPants
+  module Presenter
+    extend ActiveSupport::Concern
+
+    included do
+      class_attribute :_presented_attributes
+    end
+
+    module ClassMethods
+      # Accepts a list of attributes to be presented in the response
+      #
+      def attr_expose(*args)
+        options = args.extract_options!
+        self._presented_attributes = (self._presented_attributes || []) + args
+      end
+    end
+
+    # Override to only show model attributes marked for presentation with attr_presented
+    def serializable_hash(options = {})
+      options[:only] = (options[:only] || []) | (self.class._presented_attributes || [])
+      options[:only] = nil if options[:only].empty?
+      super(options)
+    end
+
+    ActiveSupport.on_load :active_record do
+      ActiveRecord::Base.send :include, RocketPants::Presenter
+    end
+  end
+end

spec/rocket_pants/presenter_spec.rb

@@ -0,0 +1,21 @@
+require 'spec_helper'
+require 'rocket_pants/presenter'
+
+describe RocketPants::Presenter do
+  include ControllerHelpers
+
+  use_reversible_tables :fish, :scope => :all
+
+  it 'should provide an attr_exposed method on an AR model' do
+    Fish.respond_to?(:attr_expose).should be_true
+  end
+
+  it 'should only expose certain attributes' do
+    attrs = {:token => "a", :name => "Test Fish", :latin_name => "Latin Name", :child_number => 5}
+
+    Fish.attr_expose :name
+
+    f = Fish.create! attrs
+    f.serializable_hash.keys.should == ["name"]
+  end
+end