Accept :id_param as array

lib/cancan/controller_resource.rb

@@ -128,14 +128,22 @@ def authorization_action
 
     def id_param
       if @options[:id_param]
-        @params[@options[:id_param]]
+        @params[id_param_name]
       else
         @params[parent? ? :"#{name}_id" : :id]
       end.to_s
     end
 
+    def id_param_name
+      if @options[:id_param].kind_of?Array
+        @options[:id_param].find { |id_param| @params.include?(id_param) }
+      else
+        @options[:id_param]
+      end
+    end
+
     def member_action?
-      new_actions.include?(@params[:action].to_sym) || @options[:singleton] || ( (@params[:id] || @params[@options[:id_param]]) && !collection_actions.include?(@params[:action].to_sym))
+      new_actions.include?(@params[:action].to_sym) || @options[:singleton] || ( (@params[:id] || @params[id_param_name]) && !collection_actions.include?(@params[:action].to_sym))
     end
 
     # Returns the class used for this resource. This can be overriden by the :class option.

spec/cancan/controller_resource_spec.rb

@@ -407,6 +407,14 @@ class Section
     resource.send(:id_param).class.should == String
   end
 
+  it "should load resource using the first valid ID param if id_param is Array" do
+    project = Project.create!
+    @params.merge!(:action => "show", :the_project => project.id)
+    resource = CanCan::ControllerResource.new(@controller, :id_param => [:the_project])
+    resource.load_resource
+    @controller.instance_variable_get(:@project).should == project
+  end
+
   it "should load resource using custom find_by attribute" do
     project = Project.create!(:name => "foo")
     @params.merge!(:action => "show", :id => "foo")