Fix NoMethodError

Raises NoMethodError when using ":singleton => true, :shallow => true" and parent_resource is nil

lib/cancan/controller_resource.rb

@@ -61,7 +61,11 @@ module CanCan
     end
 
     def build_resource
-      resource = resource_base.send(@options[:singleton] ? "build_#{name}" : "new")
+      if @options[:singleton] && resource_base.respond_to?("build_#{name}")
+        resource = resource_base.send("build_#{name}")
+      else
+        resource = resource_base.send("new")
+      end
       initial_attributes.each do |name, value|
         resource.send("#{name}=", value)
       end
@@ -74,7 +78,7 @@ module CanCan
     end
 
     def find_resource
-      if @options[:singleton]
+      if @options[:singleton] && resource_base.respond_to?(name)
         resource_base.send(name)
       else
         @options[:find_by] ? resource_base.send("find_by_#{@options[:find_by]}!", id_param) : resource_base.find(id_param)

spec/cancan/controller_resource_spec.rb

@@ -241,6 +241,21 @@ describe CanCan::ControllerResource do
     @controller.instance_variable_get(:@project).name.should == "foobar"
   end
 
+  it "should find record through has_one association with :singleton and :shallow options" do
+    project = Project.create!
+    @params.merge!(:action => "show", :id => project.id)
+    resource = CanCan::ControllerResource.new(@controller, :through => :category, :singleton => true, :shallow => true)
+    resource.load_resource
+    @controller.instance_variable_get(:@project).should == project
+  end
+
+  it "should build record through has_one association with :singleton and :shallow options" do
+    @params.merge!(:action => "create", :project => {:name => "foobar"})
+    resource = CanCan::ControllerResource.new(@controller, :through => :category, :singleton => true, :shallow => true)
+    resource.load_resource
+    @controller.instance_variable_get(:@project).name.should == "foobar"
+  end
+
   it "should only authorize :read action on parent resource" do
     project = Project.create!
     @params.merge!(:action => "new", :project_id => project.id)