adding can method to Active Record for fetching records matching a specific ability, still needs documentation

CHANGELOG.rdoc

@@ -1,5 +1,7 @@
 1.1.0 (not released)
 
+* Adding "can" method to Active Record for fetching records matching a specific ability
+
 * Adding conditions behavior to Ability#can and fetch with Ability#conditions - see issue #53
 
 * Renaming :class option to :resource for load_and_authorize_resource which now supports a symbol for non models - see issue #45

lib/cancan.rb

@@ -11,3 +11,4 @@ require 'cancan/ability'
 require 'cancan/controller_resource'
 require 'cancan/resource_authorization'
 require 'cancan/controller_additions'
+require 'cancan/active_record_additions'

lib/cancan/active_record_additions.rb

@@ -0,0 +1,20 @@
+module CanCan
+  # This module is automatically included into all Active Record.
+  module ActiveRecordAdditions
+    module ClassMethods
+      def can(ability, action)
+        where(ability.conditions(action, self) || {:id => nil})
+      end
+    end
+    
+    def self.included(base)
+      base.extend ClassMethods
+    end
+  end
+end
+
+if defined? ActiveRecord
+  ActiveRecord::Base.class_eval do
+    include CanCan::ActiveRecordAdditions
+  end
+end

spec/cancan/active_record_additions_spec.rb

@@ -0,0 +1,22 @@
+require "spec_helper"
+
+describe CanCan::ActiveRecordAdditions do
+  before(:each) do
+    @model_class = Class.new
+    stub(@model_class).where { :where_stub }
+    @model_class.send(:include, CanCan::ActiveRecordAdditions)
+    @ability = Object.new
+    @ability.extend(CanCan::Ability)
+  end
+  
+  it "should call where(:id => nil) when no ability is defined so no records are found" do
+    stub(@model_class).where(:id => nil) { :no_where }
+    @model_class.can(@ability, :read).should == :no_where
+  end
+  
+  it "should call where with matching ability conditions" do
+    @ability.can :read, @model_class, :foo => 1
+    stub(@model_class).where(:foo => 1) { :found_records }
+    @model_class.can(@ability, :read).should == :found_records
+  end
+end