rails 3: how to add (or perhaps substitute) a text string to an existing PDF document?

Users of our app need to print a PDF document we have pre-created, but have a placeholder string in the PDF template "YOUR_NAME_HERE" be replaced with their name. (Or, alternatively, we could no use a placeholder and add a new string with a certain font/style at a certain X,Y offset.)

Doing full PDF creation is overkill, since ALL we need to do is add their name to the PDF doc.

To make it more fun, we're hosted on Heroku which does not have local file storage, so we need to create the final PDF as something displayed in their browser that can (hopefully) be saved to local disk.

Does anyone know of a techniqu开发者_StackOverflow社区e that would let us easily add (or replace) text to an existing PDF document?

I'm not finding anything for editing PDFs in ruby. I would just look into using something like prawn to generate them, even if that is a bit overkill when only a few words are different between each.

If efficiency is an issue, you could convert the pre-made part into a PNG and then just add the text on top. It feels dirty, but it'd probably be quicker than full generation and I don't know what other options you have, since it doesn't seem like anyone has implemented a true PDF editor in ruby yet.

As far as local storage, keep in mind that you do have write access to tmp/ on Heroku, so you can use that as long as you're only going to use the file during a single request.