Can Rails Routing Helpers (i.e. mymodel_path(model)) be Used in Models?

Say I have a Rails Model called Thing. Thing has a url attribute that can optionally be set to a URL somewhere on the Internet. In view code, I need logic that does the following: ``` <% if thing.url.blank? %> <%= link_to('Text', thing_path(thing)) %> <% else %> <%= link_to('Text', thing.url) %> <% end %> ``` This conditional logic in the view is ugly. Of course, I could build a helper function, which would change the view to this: ``` <%= thing_link('Text', thing) %> ``` That solves the verbosity problem, but I would really prefer having the functionality in the model itself. In which case, the view code would be: ``` <%= link_to('Text', thing.link) %> ``` This, obviously, would require a link method on the model. Here's what it would need to contain: ``` def link (self.url.blank?) ? thing_path(self) : self.url end ``` To the point of the question, thing_path() is an undefined method inside Model code. I'm assuming it's possible to "pull in" some helper methods into the model, but how? And is there a real reason that routing only operates at the controller and view layers of the app? I can think of lots of cases where model code may need to deal with URLs (integrating with external systems, etc).