Short version: I'd like to change what is displayed in a certain rendered Node field, if the viewing user meets certain conditions. I think the Rules action "Execute Custom PHP" can do this? But I have no experience with PHP.
Less short version: On the site, users read artistic content. A link at the top of the page gives them the option to buy said content. This should give them access to a .zip file that contains Goodies.
The node's Download field shows a link to go and buy the content. On page load, if the user owns the content (determined by a Rules condition), I want the link to be replaced with a download link. Ideally, the new link would be retrieved from a hidden field on the node.
Clever use of the "hidden" parameter could also achieve this effect, but I imagine the solution would look pretty similar. Or is this at all doable in the way I've described?
Pointers to solutions or alternatives would both be appreciated. Thanks!