Adding support for automatic decoration of find_by_ methods

lib/draper/base.rb

@@ -190,9 +190,9 @@ module Draper
     def method_missing(method, *args, &block)
       if allow?(method)
         begin
-          self.class.send :define_method, method do |*args, &block|
+          self.class.send :define_method, method do |*args, &block|            
             model.send(method, *args, &block)
-          end
+          end                        
           self.send(method, *args, &block)
         rescue NoMethodError
           super
@@ -203,7 +203,11 @@ module Draper
     end
 
     def self.method_missing(method, *args, &block)
-      model_class.send(method, *args, &block)
+      if method.to_s.match(/^find_by.*/)
+        self.decorate(model_class.send(method, *args, &block))
+      else
+        model_class.send(method, *args, &block)
+      end
     end
 
     def self.respond_to?(method, include_private = false)

spec/draper/base_spec.rb

@@ -177,6 +177,34 @@ describe Draper::Base do
       pd.context.should == :admin
     end
   end
+  
+  context ".find_by_(x)" do
+    it "runs the similarly named finder" do
+      Product.should_receive(:find_by_name)
+      ProductDecorator.find_by_name("apples")
+    end
+    
+    it "returns a decorated result" do
+      ProductDecorator.find_by_name("apples").should be_kind_of(ProductDecorator)
+    end
+    
+    it "runs complex finders" do
+      Product.should_receive(:find_by_name_and_size)
+      ProductDecorator.find_by_name_and_size("apples", "large")
+    end
+    
+    it "accepts an options hash" do
+      Product.should_receive(:find_by_name_and_size).with("apples", "large", {:role => :admin})
+      ProductDecorator.find_by_name_and_size("apples", "large", {:role => :admin})
+    end
+    
+    it "uses the options hash in the decorator instantiation" do
+      pending "Figure out an implementation that supports multiple args (find_by_name_and_count_and_size) plus an options hash"
+      Product.should_receive(:find_by_name_and_size).with("apples", "large", {:role => :admin})
+      pd = ProductDecorator.find_by_name_and_size("apples", "large", {:role => :admin})
+      pd.context[:role].should == :admin
+    end
+  end
 
   context ".decorate" do
     context "without any context" do

spec/support/samples/product.rb

@@ -1,5 +1,9 @@
 class Product < ActiveRecord::Base
   include Draper::ModelSupport
+  
+  def self.find_by_name(name)
+    @@dummy ||= Product.new
+  end
 
   def self.first
     @@first ||= Product.new