link_to with callbacks ?

I’ve got an image link that’s currently using link_to_remote. The link calls a method that creates a file and completes with render :nothing => true. I’m using the :loading and :complete callbacks on link_to_remote. On :loading I call a function that renders a ‘disabled’ image while the file’s being created. When the method completes, I use the :complete callback to call another function that opens a popup containing the file that got created and then renders the original ‘enabled’ image.

The above works fine except for one thing. AFAIK, because it’s being loaded by as opposed to being sent to the browser, the file that gets rendered in the popup has to exist in the ‘public’ (or some other externally visible) directory. I need the file to not be visible externally.

The first solution I tried was to eliminate the popup (too many folks have popups disabled anyway) and change the ‘render :nothing => true’ to a ‘send_file’. That sends the file to the browser (I can see the file content in Firebug) but, I guess since the browser is expecting a JS response, it doesn’t do anything with it. Anybody know a way to send a file using RJS so I can get the ‘view or save’ dialog box?

The second solution I tried was to change the link_to_remote to link_to. That lets me send the file from a non-externally-visible location, which solves that problem, but AFAIK link_to doesn’t support the callbacks. I guess I could use the :onclick to trigger rendering the ‘disabled’ image, but can’t figure out how I’d be able to change back to the ‘enabled’ image once the file was received. Any thoughts on how I could make this work?

Any thoughts on other approaches I might try would be greatly appreciated. Like, is there maybe some way to use routes to have the‘title’, ‘location/filename’) being executed in the browser to open the popup and retrieve the file be intercepted by Rails and mapped to a hidden location?