From 236cece3b3d6b9ea58a52698d183c733bb750d51 Mon Sep 17 00:00:00 2001
From: Ryan Bates <ryan@railscasts.com>
Date: Fri, 6 Aug 2010 11:18:54 -0700
Subject: [PATCH] adding :find_by option to load_resource - closes #19

---
 lib/cancan/controller_additions.rb      | 5 +++++
 lib/cancan/controller_resource.rb       | 6 +++++-
 spec/cancan/controller_resource_spec.rb | 8 ++++++++
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/lib/cancan/controller_additions.rb b/lib/cancan/controller_additions.rb
index 4106544..3ce9d44 100644
--- a/lib/cancan/controller_additions.rb
+++ b/lib/cancan/controller_additions.rb
@@ -80,6 +80,11 @@ module CanCan
       # [:+instance_name+]
       #   The name of the instance variable to load the resource into.
       #
+      # [:+find_by+]
+      #   Find using a different attribute other than id. For example.
+      #
+      #     load_resource :find_by => :permalink # will use find_by_permlink!(params[:id])
+      #
       # [:+collection+]
       #   Specify which actions are resource collection actions in addition to :+index+. This
       #   is usually not necessary because it will try to guess depending on if the id param is present.
diff --git a/lib/cancan/controller_resource.rb b/lib/cancan/controller_resource.rb
index 0c289d4..3d4dcc6 100644
--- a/lib/cancan/controller_resource.rb
+++ b/lib/cancan/controller_resource.rb
@@ -53,7 +53,11 @@ module CanCan
     end
 
     def find_resource
-      @options[:singular] ? resource_base.send(name) : resource_base.find(id_param)
+      if @options[:singular]
+        resource_base.send(name)
+      else
+        @options[:find_by] ? resource_base.send("find_by_#{@options[:find_by]}!", id_param) : resource_base.find(id_param)
+      end
     end
 
     def authorization_action
diff --git a/spec/cancan/controller_resource_spec.rb b/spec/cancan/controller_resource_spec.rb
index fe6728a..70b8279 100644
--- a/spec/cancan/controller_resource_spec.rb
+++ b/spec/cancan/controller_resource_spec.rb
@@ -218,6 +218,14 @@ describe CanCan::ControllerResource do
     @controller.instance_variable_get(:@custom_ability).should == :some_ability
   end
 
+  it "should load resource using custom find_by attribute" do
+    @params.merge!(:action => "show", :id => 123)
+    stub(Ability).find_by_name!(123) { :some_resource }
+    resource = CanCan::ControllerResource.new(@controller, :find_by => :name)
+    resource.load_resource
+    @controller.instance_variable_get(:@ability).should == :some_resource
+  end
+
   it "should raise ImplementationRemoved when adding :name option" do
     lambda {
       CanCan::ControllerResource.new(@controller, :name => :foo)