I am trying to do the following in Drupal 7:
Users in my website will post ads and others will pay to get in touch with the author of the ad. Users that are buying the contact information have to see all of the content of the ad(node), except for the author. After they pay, they should see an extra field in the ad, telling them who the author is.
My question is: How can I control the user access per node and per user for a specific part of the node? Are there any modules for this? Also, a relation between the user and the ad would be nice, since I will later have to list all ads for a user, etc..
I found many plugins, but they seem to deny or allow access to the entire node and my functionality should be different.
Thanks in advance