Using URL path in REST app as ID

I'm a Rails newbie, so please bear with me. I want to use the URL as the ID for a RESTful resource, but using the path after the controller. The remaining portion of the URL would be the ID, rather than an integer.

So rather than just:

http://example.org/widgets/1

I want to use:

http://example.org/widgets/foo http://example.org/widgets/foo/bar http://example.org/widgets/foo/bar/baz

where foo, foo/bar and foo/bar/baz are all Widgets, not nested resources.

In the controller I'd like to do something like

@widget = Widget.find(params[:path])

where path is a string column defined as a primary key (or unique) containing strings like 'foo', 'foo/bar' and 'foo/bar/baz'

Is this possible?