Implementing #first and #last methods on decorators

lib/draper/base.rb

@@ -103,6 +103,14 @@ module Draper
     def self.all(context = {})
       Draper::DecoratedEnumerableProxy.new(model_class.all, self, context)
     end
+    
+    def self.first(context = {})
+      decorate(model_class.first, context)
+    end
+
+    def self.last(context = {})
+      decorate(model_class.last, context)
+    end
 
     # Access the helpers proxy to call built-in and user-defined
     # Rails helpers. Aliased to `.h` for convinience.

spec/draper/base_spec.rb

@@ -175,6 +175,24 @@ describe Draper::Base do
       subject.should == other
     end
   end
+  
+  context 'position accessors' do
+    [:first, :last].each do |method|
+      context "##{method}" do
+        it "should return a decorated instance" do
+          ProductDecorator.send(method).should be_instance_of ProductDecorator
+        end
+
+        it "should return the #{method} instance of the wrapped class" do
+          ProductDecorator.send(method).model.should == Product.send(method)
+        end
+
+        it "should accept an optional context" do
+          ProductDecorator.send(method, :admin).context.should == :admin
+        end
+      end      
+    end
+  end
 
   describe "collection decoration" do
 

spec/support/samples/product.rb

@@ -1,5 +1,13 @@
 class Product < ActiveRecord::Base
   include Draper::ModelSupport
+
+  def self.first
+    @@first ||= Product.new
+  end
+
+  def self.last
+    @@last ||= Product.new
+  end
   
   def self.all
     [Product.new, Product.new]